Flexible liquid crystal lenses

Abstract

An electrically switchable flexible contact lens for conforming to a user's eye is provided. The lens comprises a liquid crystal cell for changing the focal power of the contact lens, and the liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface, the liquid crystal cell comprises a diffractive optical element for correcting the user's vision, wherein the diffractive optical element is arranged to maintain the cell gap thickness by providing support at one or more locations within the cell.

Description

Technical Field

[0001] The present invention relates to flexible contact lenses.

[0002] The present invention relates to flexible contact lenses. More particularly, but not exclusively, the present invention relates to an electrically switchable contact lens. Background Art

[0003] Flexible contact lenses comprising a diffractive optical element are known. The lens may be provided with a liquid crystal that can be electrically switched between two states. In a first state, the refractive index of the liquid crystal does not match the refractive index of the diffractive optical element, and the diffractive optical element interacts with and diffracts the light. In a second state, the refractive index of the liquid crystal matches the refractive index of the diffractive optical element and there is no or very little diffraction of the incident light.

[0004] The present invention seeks to provide improved flexible contact lenses including diffractive optical elements. Summary of the invention

[0005] According to a first aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as set forth in Technical Solution 1 below.

[0006] According to a second aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 10 below.

[0007] According to a third aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 15 below.

[0008] According to a fourth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 19 below.

[0009] According to a fifth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 20 below.

[0010] According to a sixth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 21 below.

[0011] According to a seventh aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features as described in technical solution 25 below.

[0012] Preferred but optional features of the invention are set out below and in the accompanying claims.

[0013] Of course, it will be appreciated that features described in relation to one aspect of the invention may be incorporated into other aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0015] Figure 1 a schematic side cross-sectional view showing an example of a contact lens according to the first aspect of the invention, the contact lens comprising a liquid crystal cell;

[0016] Figure 2 Shown in Figure 1 A schematic side view of a liquid crystal cell used in;

[0017] Figure 3 a schematic representation showing the local alignment of liquid crystal molecules in a liquid crystal cell in an unswitched state;

[0018] Figure 4 A schematic representation showing the local alignment of liquid crystal molecules in a liquid crystal cell in a switched state;

[0019] Figure 5 Demonstrating the intensity of a diffraction profile produced by a lens comprising a liquid crystal cell, wherein the diffractive optical element has a low refractive index, the liquid crystal cell being in a switched state;

[0020] Figure 6 showing the intensity of a diffraction profile produced by a lens comprising a liquid crystal cell, wherein the diffractive optical element has a low refractive index, the liquid crystal cell being in an unswitched state;

[0021] Figure 7 Demonstrating the intensity of a diffraction profile produced by a lens comprising a liquid crystal cell, wherein the diffractive optical element has a high refractive index, the liquid crystal cell being in an unswitched state;

[0022] Figure 8 Demonstrating the intensity of a diffraction profile produced by a lens comprising a liquid crystal cell, wherein the diffractive optical element has a high refractive index, the liquid crystal cell being in a switched state; and

[0023] Fig. 9 Schematic cross-sectional views showing examples of contact lenses according to various aspects of the present invention, the contact lenses comprising two liquid crystal cells; and

[0024] Fig.10 Schematic plan view showing the alignment of the director of a liquid crystal adjacent to an alignment polymer. DETAILED DESCRIPTION

[0025] According to a third aspect of the present invention, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0026] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0027] The first liquid crystal unit includes a diffractive optical element for correcting the user's vision,

[0028] Wherein the diffractive optical element is arranged to maintain the cell gap thickness by providing support at one or more locations within the cell.

[0029] Applicants have discovered that it is feasible to use diffractive optical elements as spacers to maintain cell gap thickness in flexible ophthalmic lenses.

[0030] Maintenance of the cell gap thickness is important for maintaining the optical properties of the ophthalmic lens. In particular, maintenance of the cell gap thickness maintains a sufficiently small cell gap so that the liquid crystals can align without haze. In this regard, maintenance of the cell gap thickness may include an average decrease in the cell gap thickness across the first liquid crystal cell of no more than 15%, optionally no more than 12%, optionally no more than 10%, optionally no more than 8%, and optionally no more than 5%. Maintenance of the cell gap thickness may allow only relatively small decreases and / or increases in the cell gap thickness. In this regard, when the ophthalmic lens is deformed due to placement on the user's eye, the average change in the cell gap thickness across the first liquid crystal cell may be optionally no more than 15%, optionally no more than 12%, optionally no more than 10%, optionally no more than 8%, and optionally no more than 5%.

[0031] The average cell gap thickness in the undeformed lens is optionally at least 2.0 microns, optionally at least 3.0 microns, optionally at least 3.5 microns, optionally at least 4.0 microns, optionally at least 4.5 microns, and optionally at least 5.0 microns.

[0032] The average cell gap thickness in the undeformed lens is optionally no greater than 7.0 microns, optionally no greater than 6.5 microns, optionally no greater than 6.0 microns, optionally no greater than 5.5 microns, optionally no greater than 5.0 microns, optionally no greater than 4.5 microns and optionally no greater than 4.0 microns.

[0033] As used herein and as understood by those skilled in the art, micron is the same as micrometer.

[0034] The average cell gap thickness in the undeformed lens is optionally from 2.0 microns to 7.0 microns, optionally from 2.5 microns to 5.5 microns, optionally from 3.5 microns to 5.0 microns and optionally from 3.5 microns to 4.5 microns.

[0035] The average height of the diffractive optical element may correspond to the average cell gap thickness. Similarly, the height of the diffractive element at a point in the first liquid crystal cell may correspond to the cell gap thickness at said point of the first liquid crystal cell.

[0036] The first liquid crystal cell may be substantially free of other elements (eg, spacers) for maintaining the cell gap thickness by providing support at locations within the cell. Optionally, however, peripheral spacers may be provided at the periphery of the first liquid crystal cell in addition to the diffractive optical element.

[0037] For the avoidance of doubt, a diffractive optical element is one of a feature whose size and dimensions are sufficiently small relative to the wavelength of light impinging thereon so as to cause controlled and desired optical effects arising solely from diffraction of the light. For the avoidance of doubt, a diffractive optical element does not include a Fresnel lens.

[0038] The first liquid crystal unit can be operated between a first unswitched state and a second switched state. In the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be greater or lower than in the second state. In the first state or the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be small or zero, that is, the effective refractive index of the liquid crystal and the diffractive optical element can be approximately the same. In this background content, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be optionally not more than 0.03, optionally not more than 0.02 and optionally not more than 0.01. Such a difference in refractive index is to be calculated for wavelengths in the visible part of the electromagnetic spectrum (radiation with a wavelength from 450 to 700nm). Such a difference in refractive index can be calculated at a wavelength of 450nm, and optionally at a wavelength of 700nm. Optionally, such a difference can be calculated at multiple wavelengths from 450nm to 700nm. In the other of the first and second states, the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element do not match, and therefore, the diffractive optical element diffracts incident light. The first state may be an unswitched state, i.e., in which no or low voltage is applied to the first liquid crystal cell. The second state may be a switched state, i.e., in which a voltage is applied that switches the liquid crystal in the cell into the second state.

[0039] For the avoidance of doubt, the effective refractive index is the refractive index of the liquid crystal for light normally incident on the contact lens and on the first liquid crystal cell. In the first unswitched state, the effective refractive index may be n ave =0.5(n o +n e ), where n o is the ordinary refractive index of the liquid crystal and n e is the extraordinary refractive index of the liquid crystal. In the second switching state, the effective refractive index may be n o .

[0040] For the avoidance of doubt, "for correcting the vision of a user" includes being suitable for correcting the user's myopia, hyperopia and / or intermediate vision.

[0041] The maximum height of the diffractive optical element need not be the same across the diffractive optical element. For example, the diffractive optical element may include an inner portion and an outer portion. The maximum height of the diffractive optical element at the outer portion may be greater than the maximum height of the diffractive optical element at the inner portion. The maximum height of the diffractive optical element at the outer portion may be up to 20% greater than the maximum height of the diffractive optical element at the inner portion, optionally up to 15% greater, optionally up to 10% greater, optionally up to 7.5% greater, optionally up to 5% greater, optionally up to 2.5% greater and optionally up to 1% greater. The height of the diffractive optical element is typically the height along the optical axis.

[0042] The maximum height of the diffractive optical element at the outer portion may be at least 1% larger than the maximum height of the diffractive optical element at the inner portion, optionally at least 2% larger, optionally at least 3% larger, optionally at least 4% larger, optionally at least 5% larger, optionally at least 6% larger, optionally at least 7% larger, optionally at least 8% larger, optionally at least 10% larger, optionally at least 12.5% ​​larger, optionally at least 15% larger and optionally at least 20% larger than the maximum height of the diffractive optical element at the inner portion.

[0043] The inner portion may be at or near the center of the diffractive optical element.

[0044] The height of the diffractive optical element may increase with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase linearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase sublinearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase superlinearly with the distance from the center of the diffractive optical element.

[0045] At least a portion of the diffractive optical element may be attached to the first surface and at least a portion of the diffractive optical element may be attached to the second surface.

[0046] As mentioned above, the diffractive optical element may include a plurality of peaks and valleys, optionally annular peaks and valleys. The outer portion may include an outer peak, for example, optionally one of the ten outermost peaks, optionally one of the eight outermost peaks, optionally one of the five outermost peaks and optionally one of the three outermost peaks. The outer portion may include an outermost portion. The height of the peak may increase with the distance from the center of the diffractive optical element. The height of the peak may increase linearly with the distance from the center of the diffractive optical element. The height of the peak may increase sublinearly with the distance from the center of the diffractive optical element. The height of the peak may increase superlinearly with the distance from the center of the diffractive optical element.

[0047] At least a portion of the peak may be attached to the second surface.

[0048] The liquid crystal may comprise a cholesteric liquid crystal. In the unswitched state, the director of the liquid crystal adjacent to the first and / or second inner surface may optionally be at an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees to the first and second inner surfaces. In the unswitched state, the director of the liquid crystal far from the first and second inner surfaces (and optionally the middle between the first and second inner surfaces) may optionally be at an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees to the first and second inner surfaces. In the switched state, the director of the liquid crystal far from the first and second inner surfaces (and optionally the middle between the first and second inner surfaces) may be at an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees, and optionally at least 85 degrees to the first and second inner surfaces.

[0049] The refractive index of the diffractive optical element may be optionally at least 1.40, optionally at least 1.42, optionally at least 1.44, optionally at least 1.46 and optionally at least 1.48.

[0050] The refractive index of the diffractive optical element may be optionally not greater than 1.72, optionally not greater than 1.70, optionally not greater than 1.68, optionally not greater than 1.66, and optionally not greater than 1.64.

[0051] For example, the refractive index of the diffractive optical element may be from 1.40 to 1.72, preferably from 1.42 to 1.70, and more preferably from 1.44 to 1.68.

[0052] The contact lens may include a further optical element for correcting the user's vision. In this regard, the contact lens may include a lens body for correcting the user's vision. The lens body may provide a positive optical power, such as +0.5, +1.0 or +1.5D. The optical power of the lens body may be fixed. The addition of such a lens body may be particularly useful if the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element when the first liquid crystal cell is in the second switching state.

[0053] At both 450nm and 700nm, the refractive index of the liquid crystal is optionally 0.80 to 1.20 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the refractive index of the liquid crystal may be 0.90 to 1.10 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the refractive index of the liquid crystal may be 0.95 to 1.05 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the refractive index of the liquid crystal may be 0.97 to 1.03 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the refractive index of the liquid crystal may be 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0054] At 500 nm, the refractive index of the liquid crystal may be 0.80 to 1.20 times the refractive index of the diffractive optical element, optionally 0.90 to 1.10 times, optionally 0.95 to 1.05 times, optionally 0.97 to 1.03 times and optionally 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0055] The refractive index of the liquid crystal is the average refractive index n ave , so the calculation is: n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index.

[0056] The first liquid crystal unit may include cholesteric liquid crystal, and the refractive index of the diffractive optical element is optionally no greater than 1.57.

[0057] The first liquid crystal cell may include cholesteric liquid crystal, and the refractive index of the diffractive optical element is optionally at least 1.58.

[0058] The diffractive optical element may include a plurality of peaks and valleys, optionally annular peaks and valleys. The peaks and valleys may be concentric. At least one, optionally more than one, and optionally each of the peaks maintains the cell gap thickness by providing support at one or more locations within the cell.

[0059] The diffractive optical element may comprise at least 5 peaks, optionally at least 7 peaks and optionally at least 10 peaks. The diffractive optical element may optionally comprise no more than 20 peaks, optionally no more than 15 peaks and optionally no more than 10 peaks.

[0060] The contact lens may comprise more than one liquid crystal cell. For example, the contact lens may comprise a second liquid crystal cell. The first and second liquid crystal cells may be arranged so that light travels through both liquid crystal cells before traveling into the wearer's eye. The second liquid crystal cell may comprise the features described above in relation to the first aspect of the invention. For example, the second liquid crystal cell may comprise a diffractive optical element used as a spacer in the second liquid crystal cell.

[0061] According to a second aspect of the present invention, there is also provided an electrically switchable flexible contact lens for conforming to a user's eye, the lens comprising:

[0062] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface;

[0063] The first liquid crystal unit includes a diffractive optical element for correcting a user's vision, the diffractive optical element including an inner portion and an outer portion, a maximum height of the diffractive optical element at the outer portion being from 1% to 20% greater than a maximum height of the diffractive optical element at the inner portion.

[0064] Applicants have found that it is advantageous for the diffractive optical element to have a greater maximum height at the outer portion of the first liquid crystal cell than at the inner portion of the first liquid crystal cell, but the difference in maximum height should be limited. In particular, Applicants have found that this arrangement of the diffractive optical element can compensate for the curvature of the cornea when the contact lens is placed on the cornea. Furthermore, this arrangement of the diffractive optical element can help improve "straight vision", especially at the edge of the lens comprising the diffractive optical element. This arrangement of the diffractive optical element helps ensure that the optical path of light at the edge of the diffractive optical element is approximately the same as the optical path of light at the center of the diffractive optical element.

[0065] The height of a diffractive optical element is usually the height along the optical axis.

[0066] The maximum height is typically measured locally (ie, relative to the base or bottom of the diffractive optical element).

[0067] The maximum height of the diffractive optical element at the outer portion may be up to 15% greater, optionally up to 10% greater, optionally up to 7.5% greater, optionally up to 5% greater and optionally up to 2.5% greater than the maximum height of the diffractive optical element at the inner portion.

[0068] The maximum height of the diffractive optical element at the outer portion may be at least 2% larger, optionally at least 3% larger, optionally at least 4% larger, optionally at least 5% larger, optionally at least 6% larger, optionally at least 7% larger, optionally at least 8% larger, optionally at least 10% larger, optionally at least 12.5% ​​larger and optionally at least 15% larger than the maximum height of the diffractive optical element at the inner portion.

[0069] The height of the diffractive optical element may increase with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase linearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase sublinearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element may increase superlinearly with the distance from the center of the diffractive optical element.

[0070] The inner portion may be at or near the center of the diffractive optical element.

[0071] The diffractive optical element may extend within a chord length r. The inner portion may include a portion of the diffractive optical element within a chord length of r / 8 from the center of the diffractive optical element. The outer portion may include a portion of the diffractive optical element having a chord length from r / 4 (and optionally from 3r / 8) to r / 2.

[0072] The diffractive optical element may include a plurality of peaks and valleys, optionally annular peaks and valleys. The outer portion may include an outer peak, for example, optionally one of the ten outermost peaks, optionally one of the eight outermost peaks, optionally one of the five outermost peaks and optionally one of the three outermost peaks. The outer portion may include an outermost portion. The height of the peak may increase with the distance from the center of the diffractive optical element. The height of the peak may increase linearly with the distance from the center of the diffractive optical element. The height of the peak may increase sublinearly with the distance from the center of the diffractive optical element. The height of the peak may increase superlinearly with the distance from the center of the diffractive optical element.

[0073] The liquid crystal may comprise a cholesteric liquid crystal. In the unswitched state, the director of the liquid crystal far from the first and second inner surfaces (and optionally halfway between the first and second inner surfaces) may optionally be at an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees to the first and second inner surfaces. In the switched state, the director of the liquid crystal far from the first and second inner surfaces (and optionally halfway between the first and second inner surfaces) may be at an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees, and optionally at least 85 degrees to the first and second inner surfaces.

[0074] The average cell gap thickness in the undeformed lens is optionally at least 2.0 microns, optionally at least 3.0 microns, optionally at least 3.5 microns, optionally at least 4.0 microns, optionally at least 4.5 microns, and optionally at least 5.0 microns.

[0075] The average cell gap thickness in the undeformed lens is optionally no greater than 7.0 microns, optionally no greater than 6.5 microns, optionally no greater than 6.0 microns, optionally no greater than 5.5 microns, optionally no greater than 5.0 microns, optionally no greater than 4.5 microns and optionally no greater than 4.0 microns.

[0076] The average cell gap thickness in the undeformed lens is optionally from 2.0 microns to 7.0 microns, optionally from 2.5 microns to 5.5 microns, optionally from 3.5 microns to 5.0 microns and optionally from 3.5 microns to 4.5 microns.

[0077] The contact lens of the second aspect of the invention may include any of the features of the contact lens of the first aspect of the invention.

[0078] According to a third aspect of the present invention, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0079] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0080] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision.

[0081] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or lower than in the second state,

[0082] wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times the refractive index of the diffractive optical element,

[0083] The average refractive index of the liquid crystal is n ave , so the calculation is: n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index.

[0084] Applicants have found that in the visible part of the electromagnetic spectrum it is advantageous for the average refractive index of the liquid crystal to be similar to the average refractive index of the diffractive optical element.

[0085] The average refractive index of the liquid crystal and the refractive index of the diffractive optical element can be determined at ambient temperature (e.g., 20°C or 25°C), or at a temperature corresponding to the temperature of the human body (approximately 37°C), or at a temperature corresponding to the temperature of the cornea of ​​the eye (approximately 34°C).

[0086] At both 450nm and 700nm, the average refractive index of the liquid crystal may be 0.90 to 1.10 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the average refractive index of the liquid crystal may be 0.95 to 1.05 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the average refractive index of the liquid crystal may be 0.97 to 1.03 times the refractive index of the diffractive optical element. At both 450nm and 700nm, the average refractive index of the liquid crystal may be 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0087] At 500 nm, the average refractive index of the liquid crystal may be 0.80 to 1.20 times the refractive index of the diffractive optical element, optionally 0.90 to 1.10 times, optionally 0.95 to 1.05 times, optionally 0.97 to 1.03 times and optionally 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0088] The average refractive index of the liquid crystal is the average refractive index n ave , so the calculation is: n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index.

[0089] At 460nm, 480nm, 500nm, 520nm, 540nm, 560nm, 580nm, 600nm, 620nm, 640nm, 660nm and 680nm, the refractive index of the liquid crystal is optionally 0.80 to 1.20 times the refractive index of the diffractive optical element, optionally 0.90 to 1.10 times, optionally 0.95 to 1.05 times, optionally 0.97 to 1.03 times and optionally 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0090] At substantially all wavelengths from 450nm to 700nm, the refractive index of the liquid crystal is optionally 0.80 to 1.20 times the refractive index of the diffractive optical element. At substantially all wavelengths from 450nm to 700nm, the refractive index of the liquid crystal may be 0.90 to 1.10 times the refractive index of the diffractive optical element, optionally 0.95 to 1.05 times, optionally 0.97 to 1.03 times, and optionally 0.98 to 1.02 times the refractive index of the diffractive optical element. Those skilled in the art will appreciate that the refractive index need not be measured at all wavelengths; the refractive index varies with wavelength in a similar manner for most materials. Generally speaking, the refractive index decreases in a continuous manner from 450nm to 700nm without a minimum, maximum, or inflection point.

[0091] The first liquid crystal cell can be operated between a first and a second state. In the first state (typically the unswitched state), the director of the liquid crystal far from the first and second inner surfaces (and optionally the middle between the first and second inner surfaces) can be at an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees to the first and second inner surfaces. In the switched state (e.g., the second state), the director of the liquid crystal far from the first and second inner surfaces (and optionally the middle between the first and second inner surfaces) can be at an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees, and optionally at least 85 degrees to the first and second inner surfaces.

[0092] The lens of the third aspect of the present invention may include any features of the lens of the first and / or second aspect of the present invention.

[0093] According to a fourth aspect of the present invention, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0094] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0095] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision;

[0096] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or less than in the second state,

[0097] The refractive index of the diffractive optical element is not greater than 1.57.

[0098] Applicants have discovered that if the refractive index of the diffractive optical element is relatively low, the optical performance of the contact lens exhibits good refractive index matching with good near-field performance in the second state over a wide wavelength range.

[0099] In the first state or the second state, but preferably the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be small or zero, that is, the refractive indexes of the liquid crystal and the diffractive optical element are approximately the same. In the second state, due to the matching of the refractive indices, the diffractive element does not significantly diffract the incident light. In the first state or the second state, but preferably the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be greater than in the other states, so that the diffractive optical element diffracts the incident light.

[0100] In the first unswitched state, the effective refractive index of the liquid crystal may be the average refractive index of the liquid crystal, n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index. In the second switching state, the effective refractive index of the liquid crystal may be n o , ordinary refractive index.

[0101] The contact lens may include a lens body for correcting the user's vision. The lens body may provide a positive optical power, such as +0.5, +1.0 or +1.5D. The optical power of the lens body may be fixed. The lens body may be positioned at or near the uppermost portion of the lens, the portion facing away from the portion of the lens that contacts the wearer's eye. The addition of such a lens body may be particularly useful if the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element when the first liquid crystal cell is in the second switching state.

[0102] The refractive index of the diffractive optical element is optionally no greater than 1.55, and optionally no greater than 1.53.

[0103] The refractive index of the diffractive optical element is optionally at least 1.43, optionally at least 1.45, optionally at least 1.47 and optionally at least 1.49.

[0104] The refractive index of the diffractive optical element is optionally from 1.43 to 1.57, optionally from 1.45 to 1.55, and optionally from 1.47 to 1.55.

[0105] In the unswitched state, the director of the liquid crystal far from the first and second inner surfaces (optionally midway between the first and second inner surfaces) may optionally make an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees with the first and second inner surfaces. In the switched state, the director of the liquid crystal far from the first and second inner surfaces (and optionally midway between the first and second inner surfaces) may make an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees, and optionally at least 85 degrees with the first and second inner surfaces.

[0106] The lens of the fourth aspect of the present invention may include any features of the lens of the first, second and / or third aspect of the present invention.

[0107] According to a fifth aspect of the present invention, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0108] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0109] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision;

[0110] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or lower than in the second state,

[0111] Wherein the refractive index of the diffractive optical element is at least 1.58.

[0112] The Applicant has found that if the refractive index of the diffractive optical element is relatively high, then in the first state the optical performance of the lens exhibits less sensitivity to different wavelengths.

[0113] In the first or second state (but preferably the first state), the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be small or zero, that is, the effective refractive indexes of the liquid crystal and the diffractive optical element are approximately the same. In the first state, due to the matching of the refractive indices, the diffractive element does not significantly diffract the incident light. In the first state or the second state, but preferably the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be greater than in the other states, so that the diffractive optical element diffracts the incident light and contributes to the optical power of the contact lens.

[0114] In the first unswitched state, the effective refractive index of the liquid crystal may be the average refractive index of the liquid crystal, n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index. In the second switching state, the effective refractive index of the liquid crystal may be n o , ordinary refractive index.

[0115] The refractive index of the diffractive optical element is optionally at least 1.58, optionally at least 1.60, optionally at least 1.62, optionally at least 1.64 and optionally at least 1.66.

[0116] The refractive index of the diffractive optical element is optionally not greater than 1.70, optionally not greater than 1.68 and optionally not greater than 1.66.

[0117] The refractive index of the diffractive optical element is optionally from 1.58 to 1.70, optionally from 1.60 to 1.68, and optionally from 1.62 to 1.66.

[0118] In an unswitched state, the director of the liquid crystal far from the first and second inner surfaces and optionally the middle between the first and second inner surfaces may make an angle of no more than 20 degrees, optionally no more than 15 degrees, optionally no more than 10 degrees, optionally no more than 8 degrees, optionally no more than 5 degrees, and optionally no more than 3 degrees with the first and second inner surfaces. In a switched state, the director of the liquid crystal far from the first and second inner surfaces and optionally the middle between the first and second inner surfaces may make an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees, and optionally at least 85 degrees with the first and second inner surfaces.

[0119] According to a sixth aspect, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0120] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0121] The first liquid crystal unit includes a diffractive optical element for correcting the user's vision,

[0122] The diffractive optical element includes a plurality of peaks and valleys, wherein the peaks extend in a direction from the first inner surface to the second inner surface,

[0123] At least a portion of at least one peak is attached to the second interior surface.

[0124] Attachment of the at least one peak of the diffractive optical element to the second inner surface may restrict movement of the liquid crystal within the cell, which movement may be undesirable.

[0125] The diffractive optical element may be arranged to maintain the cell gap thickness by providing support at one or more locations within the cell.

[0126] The diffractive optical element may include a central peak and a plurality of outer peaks, at least a portion of at least one of the outer peaks being attached to the second inner surface.

[0127] At least one, optionally more than one and optionally each of the outer peaks is annular. More than one and optionally all of the outer peaks may be concentric.

[0128] At least a majority and substantially all of at least one peak may be attached to the second surface.In the event that the first liquid crystal cell is deformed, this arrangement inhibits liquid crystal from travelling through the peak.

[0129] Substantially all of each of the more than one peak may be attached to the second inner surface.

[0130] Each peak may be attached to the second inner surface.Substantially all of each peak may be attached to the second inner surface.

[0131] For example, attachment of the peak to the second inner surface may be achieved using an adhesive. Alternatively, at least one of the peak and the second inner surface may be provided with a meltable polymer that attaches the peak to the second inner surface when heated and cooled.

[0132] According to a seventh aspect of the present invention, there is provided an electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0133] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0134] The first liquid crystal cell includes a diffractive optical element for correcting a user's vision, the diffractive optical element having an operating characteristic wavelength, the operating characteristic wavelength being from 450 nm to 510 nm.

[0135] The first liquid crystal unit includes cholesteric liquid crystal,

[0136] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or lower than in the second state.

[0137] Applicants have found that it is advantageous to use a diffractive optical element having an operating characteristic wavelength that is lower than the operating characteristic wavelength that may be typically used for other lenses, such as lenses for spectacles.

[0138] For example, the operating characteristic wavelength may be no greater than 560 nm, optionally no greater than 550 nm, optionally no greater than 540 nm, optionally no greater than 530 nm, optionally no greater than 520 nm, optionally no greater than 510 nm, optionally no greater than 500 nm, optionally no greater than 490 nm, and optionally no greater than 480 nm. Applicants have discovered that it is feasible to obtain a practical contact lens having an operating characteristic wavelength up to about 550 nm because blue diffraction artifacts that can cause problems in spectacles at up to 550 nm can cause problems for contact lenses.

[0139] For example, the characteristic wavelength of operation may be at least 460 nm, optionally at least 470 nm and optionally at least 480 nm.

[0140] For example, the operating characteristic wavelength may be from 460 to 560 nm, optionally from 460 to 550 nm, optionally from 470 to 550 nm, optionally from 460 to 490 nm, optionally from 470 to 490 nm and optionally 480 nm.

[0141] Now refer to Figures 1 to 9The exemplary embodiments are described by way of example only.

[0142] exist Figure 1 and 2 An example of an electrically switchable flexible contact lens according to embodiments of the first and second aspects of the invention is shown in FIG. Figure 1 is a schematic cross-sectional view of a contact lens, which is generally represented by reference numeral 1 and includes a flexible lens body 2 in which a liquid crystal unit generally represented by reference numeral 3 has been incorporated, the flexible lens body 2 including any suitable material, such as silicone hydrogel material, silicone-free hydrogel material and silicone flexible body material. Figure 2 is a cross-sectional view of a portion of a contact lens 1. For purposes of clarity and ease of illustration, Figure 2 The liquid crystal cell 3 is depicted as being flat / planar. Those skilled in the art will appreciate that this is not the case. Figure 1 . The shape of the liquid crystal cell is more appropriately shown in . The liquid crystal cell 3 includes a diffractive optical element 4 and a liquid crystal 5 for correcting the user's vision. In short, the liquid crystal can be switched between a first unswitched state and a second switched state. In one of the switched and unswitched states, the refractive index of the liquid crystal matches the refractive index of the diffractive optical element, and the diffractive optical element has a first focal length. In the other of the switched and unswitched states, the refractive index of the liquid crystal does not match the refractive index of the diffractive optical element, and the diffractive optical element has a second focal length different from the first focal length.

[0143] The diffractive optical element 4 comprises a plurality of peaks and valleys, wherein a central peak 10A and eight annular peaks 10B, C, D, E, F, G, H, I are arranged concentrically around the central peak, thereby providing nine diffractive zones (zones being provided between each pair of adjacent peaks). For the sake of simplicity, the associated valleys are not labeled. Such diffractive elements are known to those skilled in the art of optical devices. In known lenses, spacer beads or the like would be used to maintain the cell spacing between the first inner surface 6 and the second inner surface 7. In the present example, the diffractive optical element 4 is used as a spacer to maintain the cell spacing between the first inner surface 6 and the second inner surface 7. Although Figure 2The central peak 10A is shown not in contact with the second inner surface, but this is only for illustrating that the height of the peak 10A is less than the height of 10I, which is described in more detail below. A spacer 11 is provided around the periphery of the liquid crystal cell 3 outward from the diffractive optical element 4. This spacer 11 is formed by beads having a diameter of about 4 microns dispersed in a glue. The spacing between the first inner surface 6 and the second inner surface 7 is about 4 microns, but the spacing is greater at the outer region 22 of the liquid crystal cell 3 than at the inner region 21, the difference being about 5%, the difference being due to the difference in the maximum height of the diffractive optical element 4 at the inner and outer parts. The maximum height h2 of the diffractive optical element 4 at the outer part is 4.0 microns, while the maximum height h1 of the diffractive optical element 4 at the inner part is 3.85 microns. This difference in maximum height is small, but it improves optical performance. In particular, the applicant has found that this arrangement of the diffractive optical element can compensate for the curvature of the cornea when the contact lens is placed on the cornea. Furthermore, this arrangement of the diffractive optical element may help improve "straight-through", especially at the edge of a lens comprising a diffractive optical element. The increased height of the diffractive optical element at the edge of the diffractive optical element ensures that the optical path at the edge is approximately the same as in the center of the diffractive optical element. This arrangement of the diffractive optical element ensures that the wavelength of optimal optical performance is approximately the same across the width of the diffractive optical element. Without the increased height, the optical path at the edge of the diffractive optical element would be slightly shorter than in the center of the diffractive optical element, which would be undesirable.

[0144] The height of the peaks 10A to I increases with the distance from the center of the diffractive optical element 4. The height of the peaks 10A to I may increase sub-linearly, linearly or super-linearly with the distance from the center of the diffractive optical element.

[0145] The diffractive optical element 4 is a sphere that is "chopped up" so that the wavefront traveling through the diffractive optical element has a 2π phase shift across each zone boundary (it should be recognized that strictly speaking the 2π shift only occurs at a single wavelength). It is contemplated that one can modify the shape of the diffractive optical element to have different optical powers across the zones of the diffractive optical element rather than a simple sphere (giving a simple uniform spherical power over the zone of the diffractive optical element). For example, an elliptical diffractive optical element can be used to deal with astigmatism.

[0146] The diffractive optical element 4 maintains the spacing between the first inner surface 6 and the second inner surface 7, and it suppresses a large reduction in spacing that can occur when the lens 1 (and therefore, the liquid crystal cell 3) is deformed (and therefore, the liquid crystal cell 3). The cornea is generally aspherical, and the placement of the contact lens on the cornea of ​​the wearer causes the lens to deform. In the absence of the diffractive optical element 4 used as a spacer, if the contact lens 1 is placed on the eye of the wearer, a large reduction in spacing between the first inner surface 6 and the second inner surface 7 can be observed for some parts of the liquid crystal cell 3. In addition, maintaining the cell gap thickness also maintains a cell gap thickness that is small enough so that the liquid crystal can be aligned without haze.

[0147] Applicants have observed that if the peaks are not attached to the inner surface 7, and the contact lens will deform as it would when placed on the cornea of ​​a user, liquid crystal can move outward from the space between the peaks 10A and 10B toward the outer portion of the contact lens, thereby creating a large amount of excess liquid crystal between the diffractive optical element and the inner surface 7, increasing the spacing between the first inner surface 6 and the second inner surface 7 by up to 1 micron in the region of the peaks 10G, H and I. To help reduce the displacement of the liquid crystal, at least one, optionally more than one and optionally each of the peaks 10A to I can be adhered to the inner surface 7 using an adhesive. As an alternative to the adhesive, the peaks 10A to I can be attached to the inner surface by melting, pressing and cooling the polymer 9. Still further, the peaks can be attached by physical adhesion, such as by using a plasma treatment process and the like. However, it is not critical to adhere the peaks to the inner surface 7 because the optical properties of the optical device will not be significantly negatively affected by the displacement of the liquid crystal due to the diffractive element.

[0148] In the liquid crystal cell 3, the liquid crystal is a cholesteric liquid crystal including a nematic liquid crystal doped with a chiral dopant. Such nematic liquid crystals are well known to liquid crystal scientists and technicians in the field, and for example, may include E7, BL037 and / or BL038. Such chiral dopants are well known to liquid crystal scientists and technicians in the field, such as Merck ZLI-3786, CB15 and S811. Figure 3 The local alignment of molecules in the liquid crystal cell 3 is schematically shown in FIG. Figure 2 , the inner surfaces 6 and 7 are formed by an alignment polymer that imparts alignment to the liquid crystal molecules adjacent to the rubber polymer. Depending on the viscous-flexible nature of the liquid crystal, this alignment of the liquid crystal molecules adjacent to the alignment polymer imparts a specific orientation to the liquid crystal distant from the alignment polymer. Figure 2, the layer of polymer 9 is adjacent to the liquid crystal 5. In this case, the alignment polymer 9 is a UV-curable polymer (Rolic ROP-103 / 2CP). The polymer is cured using suitably polarized UV radiation so that it imparts the desired alignment to the liquid crystal adjacent to the polymer. A similar UV-curable polymer layer is disposed on top of the diffractive optical element 4, but is not shown. The rubbing of the alignment polymer layer allows the director (the average direction of the liquid crystal molecules) adjacent to the rubber polymer layer to be approximately parallel to the first inner surface 6 and the second inner surface 7, but typically tilted by several degrees (a phenomenon known to those skilled in the art as "pre-tilt"). (As shown by the small circles adjacent to the first inner surface 6 and the second inner surface 7). The tilt of the director adjacent to the first inner surface 6 and the second inner surface 7 may be greater than several degrees. For example, the tilt of the director adjacent to the first inner surface 6 and the second inner surface 7 may be 10 to 30 degrees. Between the first inner surface 6 and the second inner surface 7, the director of the liquid crystal 5 forms a helical structure. In this Figure 3 The rod shape indicates that the director of the liquid crystal is approximately parallel to the first inner surface 6 and the second inner surface 7 and is in the plane of the figure. In this unswitched state, the effective refractive index of the liquid crystal is independent of polarization and is given by n ave =0.5(n e +n o )(Equation 1) is given by, where n e is an extraordinary refractive index and n o is the ordinary refractive index. Those skilled in the art will appreciate that it may be desirable for the pitch of the liquid crystal to be no greater than 500 nm (i.e., approximately equal to or less than the wavelength of the incident light) in order for the liquid crystal to behave to a reasonable approximation as a single refractive index material. Applicants have discovered that it is feasible for contact lenses to operate satisfactorily if the liquid crystal has a higher pitch (i.e., 600-700 nm) without significant optical artifacts. This may be beneficial because using a higher pitch may reduce the switching voltage.

[0149] exist Fig.10 9, where the arrow indicates the direction of the director of the liquid crystal adjacent to the alignment polymer. This alignment is used to provide polarization-independent operation of the contact lens. The alignment of the director of the liquid crystal adjacent to the polymer layer formed on the diffractive optical element 4 is substantially the same as Fig.10 The alignment is the same as shown in .

[0150] The liquid crystal 5 and the material from which the diffractive optical element 4 is produced can be selected to achieve the desired optical result. For example, the liquid crystal and the material used to make the diffractive optical element can be selected so that the effective refractive index of the liquid crystal matches the effective refractive index of the material used to make the diffractive optical element, and in this case, the diffractive optical element does not make any contribution to the focal power of the lens. Alternatively, if the effective refractive index of the liquid crystal does not match the effective refractive index of the material used to make the diffractive optical element, then the diffractive optical element will contribute to the focal power of the lens.

[0151] When a suitable voltage is applied to the electrodes (8A, 8B) of the liquid crystal cell, the liquid crystal molecules switch to Figure 4 , wherein the directors of the liquid crystal in the central portion 30 of the liquid crystal cell 3 are normal to the first inner surface 6 and the second inner surface 7. This realignment of the liquid crystal provides different effective refractive indices. In some cases, when the liquid crystal is in the switched state, the effective refractive index of the liquid crystal may match the refractive index of the material used to make the diffractive optical element 4, in which case the diffractive optical element does not contribute to the focal power of the lens. Conversely, when the liquid crystal is in the switched state, the effective refractive index of the liquid crystal may not match the refractive index of the material used to make the diffractive optical element 4, in which case the diffractive optical element contributes to the focal power of the lens.

[0152] Now refer to Figure 1 and 2 An example of an embodiment of a contact lens according to the third aspect of the present invention is described. An electrically switchable flexible contact lens is represented by reference numeral 1. The lens 1 includes a liquid crystal cell 3 for changing the focal length of the contact lens. The liquid crystal cell 3 includes a diffractive optical element 4 and a cholesterol liquid crystal 5 for correcting the user's vision. The liquid crystal cell 3 can operate between a switched state and an unswitched state. The diffractive optical element is made of MR10, and the diffractive optical element has a refractive index of 1.63. In the unswitched state, the liquid crystal matches the effective refractive index of the diffractive optical element, and therefore, the diffractive optical element does not contribute to the focal length of the lens. The average refractive index of the liquid crystal is calculated according to equation 1 above. The average refractive index of the liquid crystal effectively matches the refractive index of the diffractive optical element at all visible wavelengths (i.e., from 450 to 700 nm). This matching of the refractive index at all visible wavelengths provides improved optical performance because the amount of diffraction observed from the diffractive optical element is minimized due to the matching of the refractive index across the visible spectrum. Those skilled in the art will appreciate that an exact match of the refractive index across the entire visible spectrum is not required.

[0153] Now refer to Figure 1 and 2An example of an embodiment of a contact lens according to the fourth aspect of the invention is described. The lens is generally indicated by reference numeral 1 and comprises a liquid crystal cell 3 for changing the focal power of the contact lens. The liquid crystal cell 3 comprises a diffractive optical element 4 and a cholesterol liquid crystal 5 for correcting the user's vision. The lens is further provided with a +1D protrusion (not shown) on its upper surface. The liquid crystal cell 3 is operable between a first unswitched state and a second switched state. In the first state, the liquid crystal molecules are as described above with reference to Figure 3 Describes the general orientation. The average refractive index of the liquid crystal is 1.63. The diffractive optical element 4 is made of Trivex and has a refractive index of 1.51. In the first unswitched state, there is a mismatch between the refractive index of the liquid crystal and the diffractive optical element. This causes the diffractive optical element to contribute to the focal power of the lens. The diffractive optical element contributes -1D to the lens, and therefore, the total focal power of the lens considering the contribution of the diffractive optical element 4 and the +1D bulge is 0D. This can be regarded as a far vision state. In the second switching state, the effective refractive index of the liquid crystal 5 is 1.51, and there is a match between the refractive index of the liquid crystal and the diffractive optical element. This causes the diffractive optical element to not contribute to the focal power of the lens. Therefore, the total focal power of the lens is +1D. This is a myopic vision state. In the event of a power failure, the contact lens is preset to far vision, i.e., an optical power of 0D.

[0154] The applicant has found that it is possible to obtain an extremely good match between the effective refractive index of the liquid crystal and the material constituting the diffractive optical element for all visible wavelengths of light when the liquid crystal cell has been switched to the second state. Figure 5 The effective refractive index (n) of the liquid crystal and the material constituting the diffractive optical element is shown when the liquid crystal unit is switched to the second state. o ) is substantially the same for all visible wavelengths of light. In this regard, the solid line shows the effective refractive index of the liquid crystal and the diffractive optical element. The effective refractive index of the liquid crystal and the diffractive optical element is effectively the same from 400nm to 700nm. This excellent match of refractive index results in the diffractive optical element not contributing to the optical power of the lens. In addition, Figure 5 The intensity of various order diffraction profiles observed from the diffractive optical element is shown. In this regard, the dashed line shows the 0th order diffraction profile, the chain line (long dashed line separated by dots) shows the 1st order diffraction profile and the dotted line shows the 2nd order diffraction profile. Note that Figure 5 The 1st and 2nd order diffraction profiles shown in are shown multiplied by 100. As can be seen, substantially all of the light incident on the contact lens is transmitted, with very little light being diffracted at all wavelengths with very small 1st and 2nd order diffraction profiles.

[0155] Figure 6The intensity of various diffraction peaks from the diffractive optical element as a function of wavelength is shown when the liquid crystal cell 3 is in a first, unswitched state. In this case, there is a mismatch between the effective refractive index of the liquid crystal and the diffractive optical element, and therefore the diffractive optical element contributes to the focal power of the lens. In this regard, the dashed line shows the 0th order diffraction profile, the chain line (long dashed line separated by dots) shows the 1st order diffraction profile and the dotted line shows the 2nd order diffraction profile. Figure 6 It is shown that there is some wavelength dependence, but the optical performance of the lens is still good. Surprisingly, the applicants have found that, although there is some wavelength dependence of the optical response of the contact lens, the lateral rainbow effect that would be observed in glasses is not observed in the contact lens. Thus, the applicants have demonstrated that it is feasible to obtain a lens with good optical properties using a diffractive optical element with a relatively low refractive index (i.e., no greater than 1.57).

[0156] Now refer to Figure 1 and 2 An example of an embodiment of a contact lens according to the fifth aspect of the invention is described. The lens is generally indicated by reference numeral 1 and comprises a liquid crystal cell 3 for changing the focal power of the contact lens. The liquid crystal cell 3 comprises a diffractive optical element 4 and a cholesterol liquid crystal 5 for correcting the vision of a user. The liquid crystal cell 3 is operable between a first unswitched state and a second switched state, wherein in the first state, the difference in the refractive index of the liquid crystal and the diffractive optical element is less than in the second state. The refractive index of the diffractive optical element is 1.63. In the first unswitched state, the effective refractive index of the liquid crystal 5 is 1.63, and there is a match between the refractive index of the liquid crystal and the diffractive optical element. This results in the diffractive optical element not contributing to the focal power of the lens. Therefore, the total focal power of the lens is 0D. This can be regarded as a far vision state. In the second switched state, the effective refractive index of the liquid crystal 5 is 1.51, and there is a mismatch between the refractive index of the liquid crystal and the diffractive optical element. This results in the diffractive optical element contributing to the focal power of the lens. Therefore, the total focal power of the lens is +1D. This can be regarded as a myopic or near vision state. In the event of a power failure, the contact lenses are preset to distance vision, i.e., an optical power of 0D.

[0157] Applicants have found that when the liquid crystal cell is in a first, unswitched state, it is possible to obtain a good match between the effective refractive indices of the liquid crystal and the material constituting the diffractive optical element for all visible wavelengths of light, with only a small difference between the refractive indices at lower wavelengths (sub 500 nm). In this regard, the refractive index of the liquid crystal is shown as a solid line, and the refractive index of the diffractive optical element is shown as a non-bold dashed line next to the solid line. This excellent match of the refractive indices results in the diffractive optical element not contributing significantly to the optical power of the lens. Figure 7The intensity of various order diffraction profiles observed from a diffractive optical element is shown. In this regard, the bold dashed line shows the 0th order diffraction profile, the chain line (long dashed line separated by dots) shows the 1st order diffraction profile and the dotted line shows the 2nd order diffraction profile. Figure 7 The 1st and 2nd order diffraction profiles shown in are shown multiplied by 10. It can be seen that substantially all of the light incident on the contact lens is transmitted, with very little light being diffracted at all wavelengths with very small 1st and 2nd order diffraction profiles.

[0158] Figure 8 The intensity of various diffraction peaks from the diffractive optical element as a function of wavelength is shown when the liquid crystal cell 3 is in the second switching state. In this case, there is a mismatch between the effective refractive index of the liquid crystal and the diffractive optical element, and therefore, the diffractive optical element contributes to the focal power of the lens. In this regard, the bold dashed line shows the 0th order diffraction profile, the chain line (long dashed line separated by dots) shows the 1st order diffraction profile and the dotted line shows the 2nd order diffraction profile. Figure 8 It was shown that there is very little wavelength dependence and the optical performance of the lens is still good. Thus, the applicants have demonstrated that it is feasible to obtain lenses with good optical properties using diffractive optical elements with a relatively high refractive index (i.e., at least 1.58). Surprisingly, the applicants have found that, although there is some wavelength dependence of the optical response of the contact lens, the lateral rainbow effect that would be observed in glasses is not observed in the contact lens.

[0159] The exemplary contact lenses described above provide unexpectedly good peripheral imaging performance. In this regard, one would expect light to be incident on the diffractive optical element from a wide range of angles, and this wide variation in the angle of incidence and the curvature of the cornea results in large variations in the optical path length through the diffractive optical element, resulting in poor optical performance. However, applicants have discovered that peripheral light that enters the contact lens and travels through the pupil travels through portions of the diffractive optical element that are approximately normal to the incoming light, i.e., the light comes from approximately the same direction and there is less variation in the angle of incidence. This results in good peripheral imaging performance.

[0160] Furthermore, as the incident angle of the light increases from the normal, the amount of light that travels through the diffractive optical element decreases. At a certain angle, essentially no light will travel through the diffractive optical element and no optical artifacts will be seen. For example, for light incident at about 53° and a 5 mm pupil size, approximately half of the detected beam is incident on the diffractive optical element and the other half travels through the non-diffractive region of the contact lens. For light with higher incident angles, the active area of ​​the diffractive optical element exposed to the light is reduced even further so that when the beam moves completely out of the diffractive region, the optical artifact becomes negligible. Thus, to the user, there is no abrupt start / stop of the diffractive region, only a smoothly varying contribution amplitude. For the eyeglass lens embodiment, there appears to be a sharp jump between looking through the diffractive optical element and not looking through the diffractive optical element.

[0161] Applicants have also found that the astigmatism of peripheral light induced by incident light traveling through a diffractive optical element at non-normal angles is acceptable (about 0.3D on average).

[0162] Now refer to Figure 1 An example of an embodiment of a flexible contact lens according to the seventh aspect of the present invention is described. The lens is substantially the lens described above in relation to the fifth aspect of the present invention. The lens is generally indicated by reference numeral 1 and includes a liquid crystal cell 3 for changing the focal power of the contact lens and having a cell gap thickness between a first inner surface and a second inner surface. The liquid crystal cell 3 includes a diffractive optical element 4 and a cholesterol liquid crystal 5 for correcting the user's vision. The liquid crystal cell 3 can be operated between a first state and a second state, wherein in the first state, the difference between the effective refractive index of the liquid crystal and the diffractive optical element is greater than in the second state. The liquid crystal cell and the diffractive optical element have an operating characteristic wavelength, which is from 450nm to 510nm. The operating characteristic wavelength is a wavelength at which one or more properties of the lens are optimized. For example, one or more properties may include the transmission of the lens when the liquid crystal cell is in a state in which the effective refractive index of the liquid crystal matches the effective refractive index of the diffractive optical element or in a state in which the effective refractive index of the liquid crystal does not match the effective refractive index of the diffractive optical element. Figure 8 Demonstrates how the properties of a contact lens can be optimized at 480 nm. One skilled in the art will appreciate that other optical properties can be optimized at or near 480 nm. One skilled in the art will appreciate that the optimization can be determined by changing the liquid crystal, for example, so as to change the refractive index of the liquid crystal or the cell spacing between the first and second interior surfaces.

[0163] The effective refractive index of the liquid crystal depends on the orientation of the molecules of the liquid crystal. For example, in the unswitched state, the effective refractive index of the liquid crystal is the average refractive index calculated by equation 1, as mentioned above. In the switched state, the effective refractive index of the liquid crystal is n o .

[0164] The contact lenses of all aspects of the present invention may include more than one liquid crystal cell, as will now be described with reference to Fig. 9 Description. An example of a contact lens according to the first aspect of the invention is generally indicated by reference numeral 101. Lens 101 comprises a first liquid crystal cell 3 and a second liquid crystal cell 3' disposed in a lens body 2. The first liquid crystal cell 3 is substantially as described above in relation to the contact lens of the first aspect of the invention. The second liquid crystal cell 3' is substantially identical to the first liquid crystal cell 3. Those skilled in the art will appreciate that this need not be the case.

[0165] Those skilled in the art will appreciate that the lenses of the present invention may include diffractive optical elements other than the diffractive optical elements described above. In this regard, the number of diffractive zones is proportional to the optical power of the diffractive lens (in diopters) and is also proportional to the square of the diameter of the diffractive optical element. Thus, the smaller the diffractive optical element, the fewer diffractive zones are required to produce a given optical power. Table 1 below shows the number of diffractive zones required to produce a given focal power for a given diameter of a diffractive optical element.

[0166]

[0167] Table 1 - Number of diffractive zones required to achieve a specific focal power for a given diameter of a diffractive optical element

[0168] Of course, it will be appreciated that features described in relation to one aspect of the invention may be incorporated into other aspects of the invention. For example, the method of the invention may incorporate any features described with reference to the apparatus of the invention and vice versa.

[0169] Further aspects of the invention will now be described with reference to the following clauses:

[0170] Clause A1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0171] a first liquid crystal cell for changing the power of an ophthalmic lens and having a cell gap thickness between a first inner surface and a second inner surface,

[0172] The first liquid crystal unit includes a diffractive optical element for correcting the user's vision,

[0173] Wherein the diffractive optical element is arranged to maintain the cell gap thickness by providing support at one or more locations within the first liquid crystal cell.

[0174] Clause A2—A lens as recited in Clause A1 , comprising a peripheral spacer disposed at a periphery of the first liquid crystal cell to maintain the cell gap thickness in addition to the diffractive optical element.

[0175] Item A3 - A lens according to Item A1 or A2, wherein the first liquid crystal unit includes a cholesterol liquid crystal, and the first liquid crystal unit can be operated between a first unswitched state and a second switched state, wherein in one of the first and second states, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater than in the other of the first and second states.

[0176] Clause A4—A lens according to clause A3, wherein in the other of the first and second states, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is approximately zero.

[0177] Clause A5—A lens according to any one of Clauses A1 to A4, wherein the diffractive optical element comprises an inner portion and an outer portion, the height of the diffractive optical element at the outer portion being greater than the height of the diffractive optical element at the inner portion.

[0178] Clause A6—A lens as set forth in any of Clauses A1 to A5, wherein at least a portion of the diffractive optical element is attached to the first inner surface and at least a portion of the diffractive optical element is attachable to the second inner surface.

[0179] Clause A7—A lens according to any one of clauses A1 to A6, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times the refractive index of the diffractive optical element, the average refractive index being n ave =0.5(n e +n o ),

[0180] where n e is an extraordinary refractive index and n o is the ordinary refractive index.

[0181] Clause A8—A lens as described in Clause A7, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element.

[0182] Clause B1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0183] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface;

[0184] The first liquid crystal unit includes a diffractive optical element for correcting user's vision, the diffractive optical element including an inner portion and an outer portion, a height of the diffractive optical element at the outer portion being from 1% to 20% greater than a height of the diffractive optical element at the inner portion.

[0185] Clause B2—A lens according to clause B1, wherein the height of the diffractive optical element at the outer portion is at least 3% and up to 15% greater than the height of the diffractive optical element at the inner portion.

[0186] Clause B3—A lens according to clause Bl or B2, wherein the diffractive optical element comprises a plurality of peaks and valleys, and the outer portion comprises an outer peak, optionally an outermost peak.

[0187] Item B4 - A lens according to any one of items B1 to B3, wherein the diffractive optical element extends within a chord length r, the inner portion includes a portion of the diffractive optical element within a chord length of r / 8 from the center of the diffractive optical element, and the outer portion includes a portion of the diffractive optical element having a chord length from 3r / 8 to r / 2.

[0188] Item B5 - A lens according to any one of Items B1 to B4, wherein the liquid crystal comprises cholesterol liquid crystal, and optionally, in an unswitched state, the director of the liquid crystal may make an angle of no more than 5 degrees with the first and second inner surfaces, and in a switched state, the director of the liquid crystal may make an angle of at least 60 degrees, optionally at least 70 degrees, optionally at least 80 degrees and optionally at least 85 degrees with the first and second inner surfaces.

[0189] Clause C1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0190] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0191] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision.

[0192] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or lower than in the second state,

[0193] Wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times the refractive index of the diffractive optical element, and the average refractive index of the liquid crystal is n ave, so it is calculated as n ave =0.5(n e +n o ):

[0194] where n e is an extraordinary refractive index and n o is the ordinary refractive index.

[0195] Clause C2—A lens as described in clause C1, wherein at both 450nm and 700nm, the refractive index of the liquid crystal is from 0.90 to 1.10 times the refractive index of the diffractive optical element.

[0196] Clause C3—A lens as described in clause C1 or C2, wherein at both 450nm and 700nm, the refractive index of the liquid crystal is from 0.95 to 1.05 times the refractive index of the diffractive optical element.

[0197] Clause C4—A lens as described in any of clauses C1 to C3, wherein at 500 nm, the refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element.

[0198] Clause D1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0199] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0200] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision.

[0201] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or less than in the second state,

[0202] Wherein the refractive index of the diffractive optical element is not greater than 1.57.

[0203] Clause E1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0204] a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface,

[0205] The first liquid crystal unit includes a diffractive optical element and a cholesteric liquid crystal for correcting the user's vision.

[0206] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or less than in the second state,

[0207] Wherein the refractive index of the diffractive optical element is at least 1.58.

[0208] Clause F1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0209] a first liquid crystal cell for changing the power of an ophthalmic lens and having a cell gap thickness between a first inner surface and a second inner surface,

[0210] The first liquid crystal unit includes a diffractive optical element for correcting the user's vision,

[0211] The diffractive optical element includes a plurality of peaks and valleys, wherein the peaks extend in a direction from the first inner surface to the second inner surface.

[0212] At least a portion of at least one peak is attached to the second interior surface.

[0213] Clause F2—A lens as described in clause F1, wherein the diffractive optical element comprises a central peak and a plurality of outer peaks, at least a portion of at least one of the outer peaks being attached to the second inner surface.

[0214] Clause F3—A lens as described in clause F2, wherein at least one, optionally more than one, and optionally each of the outer peaks is annular.

[0215] Clause F4—A lens according to any of clauses F1 to F3, at least a majority, and optionally substantially the entire periphery, of at least one peak being attached to the second inner surface.

[0216] Clause G1—An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising:

[0217] a first liquid crystal cell for changing at least one optical property of the contact lens and having a cell gap thickness between a first inner surface and a second inner surface,

[0218] The first liquid crystal unit includes a diffractive optical element for correcting the user's vision, the diffractive optical element having an operating characteristic wavelength, the operating characteristic wavelength being from 450 nm to 510 nm;

[0219] The first liquid crystal unit includes cholesteric liquid crystal,

[0220] The first liquid crystal cell is operable between a first unswitched state and a second switched state, wherein in the first state the difference between an effective refractive index of the liquid crystal and a refractive index of the diffractive optical element is greater or less than in the second state.

[0221] Clause G2—A lens according to clause G1, wherein the operating characteristic wavelength is from 460 to 490 nm, optionally from 470 to 490 nm and optionally 480 nm.

[0222] Although the present invention has been described and illustrated with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention lends itself to many different variations not specifically described herein. By way of example only, certain possible variations will now be described.

[0223] The use of the diffractive optical element is not limited to liquid crystal cells including cholesteric liquid crystals. For example, other types of liquid crystals including undoped nematic and smectic liquid crystals may be used.

[0224] In the case of integers or elements with known, obvious or foreseeable equivalents mentioned in the foregoing description, such equivalents are incorporated herein in a manner as if individually stated. Reference should be made to the claims for determining the true scope of the present invention, which should be interpreted as covering any such equivalents. The reader should also understand that the integers or features of the present invention described as preferred, advantageous, convenient or the like are optional and do not limit the scope of the appended claims. Furthermore, it should be understood that such optional integers or features, although having possible benefits in some embodiments of the present invention, may be undesirable and therefore may not exist in other embodiments.

Claims

1. An electrically switchable flexible contact lens for conforming to an eye of a user, the lens comprising: a first liquid crystal cell for changing the focal power of the contact lens and having a cell gap thickness between the first inner surface and the second inner surface, The first liquid crystal unit includes a diffractive optical element for correcting the user's vision, wherein the diffractive optical element is arranged to maintain the cell gap thickness by providing support at one or more locations within the cell, and The diffractive optical element includes an inner part and an outer part, and the maximum height of the diffractive optical element at the outer part is greater than the maximum height of the diffractive optical element at the inner part, so that the diffractive optical element at the outer part supports and separates the first inner surface and the second inner surface at a greater distance at the outer area of ​​the first liquid crystal unit than at the inner area of ​​the first liquid crystal unit.

2. The electrically switchable flexible contact lens according to claim 1, further comprising, in addition to the diffractive optical element, a peripheral spacer disposed at the periphery of the first liquid crystal unit for maintaining the cell gap thickness.

3. The electrically switchable flexible contact lens of claim 1 , wherein the first liquid crystal unit comprises a cholesteric liquid crystal, and the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein in one of the first unswitched state and the second switched state, the difference between an effective refractive index of the liquid crystal and a refractive index of the diffractive optical element is greater than in the other of the first unswitched state and the second switched state.

4. The electrically switchable flexible contact lens of claim 3, wherein in the other of the first unswitched state and the second switched state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is approximately zero.

5. The electrically switchable flexible contact lens of claim 1, wherein at least a portion of the diffractive optical element is attached to the first inner surface and at least a portion of the diffractive optical element is attachable to the second inner surface.

6. The electrically switchable flexible contact lens of claim 1, wherein the first liquid crystal unit comprises a liquid crystal, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times the refractive index of the diffractive optical element, the average refractive index being n ave =0.5(n e +n o ), where n e is an extraordinary refractive index and n o is the ordinary refractive index.

7. An electrically switchable flexible contact lens according to claim 6, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element.

8. The electrically switchable flexible contact lens of claim 1, further comprising a second liquid crystal cell for changing the focal power of the contact lens, the second liquid crystal cell optionally comprising features of the first liquid crystal cell.

9. The electrically switchable flexible contact lens according to claim 1, wherein the maximum height of the diffractive optical element at the outer portion is from 1% to 20% greater than the maximum height of the diffractive optical element at the inner portion.

10. The electrically switchable flexible contact lens of claim 9, wherein the maximum height of the diffractive optical element at the outer portion is 3% to up to 15% greater than the maximum height of the diffractive optical element at the inner portion.

11. An electrically switchable flexible contact lens according to claim 10, wherein the liquid crystal comprises cholesteric liquid crystal.

12. The electrically switchable flexible contact lens of claim 11, wherein in an unswitched state, the director of the liquid crystal may form an angle of no more than 5 degrees with the first inner surface and the second inner surface, and in a switched state, the director of the liquid crystal may form an angle of at least 60 degrees with the first inner surface and the second inner surface.

13. The electrically switchable flexible contact lens of claim 11, wherein in a switched state, the director of the liquid crystal can be at least 70 degrees from the first inner surface and the second inner surface.

14. The electrically switchable flexible contact lens of claim 11, wherein in a switched state, the director of the liquid crystal can be at least 80 degrees from the first inner surface and the second inner surface.

15. The electrically switchable flexible contact lens of claim 11, wherein in a switched state, the director of the liquid crystal can make an angle of at least 85 degrees with the first inner surface and the second inner surface.

16. The electrically switchable flexible contact lens of claim 9, wherein the diffractive optical element comprises a plurality of peaks and valleys, and the outer portion comprises outer peaks.

17. An electrically switchable flexible contact lens according to claim 16, wherein the outer portion includes an outermost peak.

18. An electrically switchable flexible contact lens according to claim 9, wherein the diffractive optical element extends within a chord length r, the inner portion includes a portion of the diffractive optical element within a chord length of r / 8 from the center of the diffractive optical element, and the outer portion includes a portion of the diffractive optical element having a chord length from 3r / 8 to r / 2.

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