Geometric volume-controlled corneal refractive treatment contact lens

Abstract

To provide a contact lens for treating myopia in a patient's eye.SOLUTION: A contact lens for treating myopia in a patient's eye comprises a front surface and a rear surface having meridians, the meridians defining: a central compression region in contact with the cornea prior to treatment; a volume control region surrounding the central compression region; a secondary compression region surrounding the volume control region and in contact with the cornea prior to treatment; a peripheral relief region surrounding the secondary compression region; a landing region surrounding the peripheral relief region and in contact with the cornea prior to treatment; and an edge surrounding the landing region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of this disclosure relates generally to contact lenses, and more particularly, some embodiments relate to contact lenses and non-surgical methods for reshaping the cornea of ​​the eye to treat vision disorders. [Background technology]

[0002] Hard contact lenses were commercialized over 60 years ago. Early fitting concepts rapidly evolved into dual-curve and triple-curve designs to facilitate the necessary lens movement for tear exchange within the non-gas-permeable lens. Lens movement with blinking was essential to allow a fresh tear layer to move from the tear meniscus at the lower eyelid onto the underlying lens. Simple lathes used during the first 20 years of commercialization allowed for multiple concentric curves to be fabricated, interlocking to avoid sharp joints.

[0003] The central radius of the lens was selected in relation to the central corneal curvature. The radius of the base curve could be greater than or less than the central corneal curvature, depending on the design concept. The radius of the first concentric zone (quadratic surface) was always greater than the radius of the base curve, and the radius of each successive zone peripheral to the inner zone was also greater than that of the zone immediately inside it. Historically, lenses have had three or more zones. The radius of all zones outside the central optical zone was, as a rule, greater than the radius of the cornea below it. This was a requirement to facilitate lens movement and tear exchange.

[0004] Lens designs like these demonstrated a 1.0-1.5 mm shift with blinking and lateral eye movement, which required some getting used to. Edge design was also critical to achieve comfort and prevent trauma to the bulbar and palpebral conjunctiva.

[0005] The advent of gas permeable materials reduced the need for the high levels of movement and radial and axial edge lift required with non-gas permeable lenses. However, traditional design concepts continued to be used with new materials. Over time, lenses were designed to have less clearance. While the original designs typically had a quadratic radius approximately 1.4 mm larger than the base radius, gas permeable designs tended to be 0.8 mm larger than the base radius. The average difference in base radius from the central corneal radius also tended to be smaller.

[0006] Over the past decade, there has also been a trend toward larger mean overall diameters. As a result, modern gas permeable lenses are larger and align more closely with the cornea. While early non-gas permeable lenses made of polymethyl methacrylate (PMMA) were designed with axial edge protrusions on the order of 100 μm, modern lenses can have axial edge protrusions as small as 50 μm. Furthermore, modern gas permeable lenses have demonstrated movement of less than 0.25 mm, compared with 1.0–1.5 mm for early PMMA lenses.

[0007] Yet current design concepts and teachings continue to use multiple concentric zone features and their respective modulations. Lens design programs refer to the width and local radius of each zone. Educational curricula teach modulation in terms of making radii "flatter" or "steeper" and "narrower" or "wider." Because there are no commonly available, accurate metrology methods for measuring actual lens clearance and fit determinations rely on sodium fluorescein observations, fit evaluation is an art rather than a measurement-based science.

[0008] Market trends also call for time-efficient management of contact lens fittings. Chair time must be short and first-time success rate is an important measure for productivity and optimal distribution. The lens fitting concept must be simple and not require much training to be successful.

[0009] Gas permeable hard contact lens designs for nocturnal corneal reshaping have evolved primarily through the use of rational fitting systems that modulate predetermined regional parameters to control the relationship between the apical lens radius and the apical corneal radius, the relationship between the midperipheral lens sagittal depth and the midperipheral corneal sagittal depth, and the alignment of the lens periphery relative to the peripheral cornea. As known to those skilled in the art, all commercially available lens designs are rotationally symmetric, even though the cornea is not rotationally symmetric. The consequence of placing a rotationally symmetric lens on a non-rotationally symmetric cornea is lens decentration. Random treatment accuracy is also an undesirable result.

[0010] There have been many attempts to fit rotationally symmetric lenses to non-rotationally symmetric eyes with significant irregular elevation differences. In some cases, toric peripheral designs or dual elevation designs have been used to address orthogonal corneal elevation differences. There is also a need for non-orthogonal elevation control, which is achieved by designing lenses with individual semi-meridian elevation control points. Each semi-meridian of the lens can be designed to have a predetermined elevation at each control point, defined by its distance from the geometric center of the lens. The elevation or sagittal depth of each point from the posterior geometric center of the lens is determined by a design philosophy algorithm that describes the relationship between the inferior eye topography at the same location and the desired sagittal depth. These elevation differences correspond to the irregular elevation of the inferior cornea when the lens is applied to the eye.

[0011] Unfortunately, the standard design paradigm using concentric curvatures results in a non-central lens that contacts the cornea near the apex, random tear volume under second-order reverse curvature, and variable lens-to-corneal contact in the peripheral alignment region. Consequences of second-generation nighttime corneal reshaping lenses include the induction of higher-order aberrations and an inability to accurately and consistently produce the mid-peripheral power necessary for consistent myopia control. While second-generation designs have attempted to address corneal asymmetry, the use of coaxial and concentric radii of curvature is inherently self-limiting. Precision and consistency in fitting are questionable.

[0012] The same problem exists with third-generation designs that incorporate a cubic polynomial in the second region of the lens. In manufacturing third-generation designs, varying a cubic polynomial with semi-meridian to create non-rotationally symmetric hardness has not been commercially available, and regulatory approval does not include the use of individual semi-meridian height control. Furthermore, third-generation designs do not teach control of the volume between the pre-treatment cornea and the lens in the mid-periphery, control of the inward angle for the secondary compression region of the lens, or the inclusion of a secondary clearance region to compress the mid-peripheral corneal contact region into the cornea.

[0013] The skill level of the fitter must be high, and even though third-generation lens designs address specific semi-meridian sagittal depths, finding an optimal fit still requires extensive fitting sets and lens reordering. Summary of the Invention [Means for solving the problem]

[0014] Embodiments of the devices and methods may include one or more of the following features: The posterior surface of the contact lens of some embodiments has a shape determined to geometrically control an area along at least one semi-meridian of the space between the contact lens surface and the inferior corneal surface, the area being defined by a first radial position of the posterior surface, a second radial position of the posterior surface, and the same radial position of the corneal surface to be treated. The posterior surface of the contact lens of some embodiments has a predetermined inward angle that is predetermined from the point of contact between the inferior corneal surface to be treated and the mid-peripheral portion of the lens, forming the peripheral side of the geometrically controlled area of ​​the space between the posterior surface of the contact lens and the inferior corneal surface.

[0015] In general, one aspect of the present disclosure features a contact lens for reshaping a pre-treatment cornea of ​​a patient's eye, comprising an anterior surface and a posterior surface having a semi-meridian that defines a central compression region in contact with the treatment cornea, a volume control region around the central compression region, a secondary compression region around the volume control region in contact with the pre-treatment cornea, a peripheral relief region around the secondary compression region, a landing region around the peripheral relief region in contact with the treatment cornea, and a peripheral edge of the landing region.

[0016] Embodiments of the contact lens may include one or more of the following features: In some embodiments, the radius of the central compression region is spherical. In some embodiments, the radius of the central compression region is aspherical. In some embodiments, the diameter of the central compression region is between 3.0 mm and 7.0 mm. In some embodiments, the volume control region is defined by four or more geometric control points connected by one of a spline, a polynomial, or a combination of conic and non-conic sections, wherein a second geometric control point is located around the first geometric control point, a third geometric control point is located around the second geometric control point, a fourth geometric control point contacts the pre-treatment cornea, and a fourth geometric control point is located around the third geometric control point. In some embodiments, the first geometric control point of the volume control region is located between 5 μm and 80 μm away from the pre-treatment cornea in the z-axis direction. In some embodiments, the second geometric control point of the volume control region is located around the pre-treatment cornea in the z-axis direction so as to define a predetermined area between the posterior surface and the pre-treatment cornea within the volume control region. In some embodiments, the third geometric control point of the volume control region is positioned to define a predetermined angle between (i) a line connecting the third geometric control point and the fourth geometric control point and (ii) a horizontal line passing through the fourth geometric control point. In some embodiments, the semi-chord radial distance of the fourth geometric control point is within a range of 2.6 mm to 5.2 mm. In some embodiments, the secondary compression region has a width within a range of 0.2 mm to 0.8 mm. In some embodiments, the secondary compression region is defined by a shape having one or more control points within the secondary compression region, the shape being defined by one of a spline, a polynomial, and a convex conic section. In some embodiments, the peripheral relief region is defined by one or more control points spaced apart in the z-axis direction from the pre-treatment cornea at a distance of 6 μm or more per diopter to reduce central refractive error. In some embodiments, the peripheral relief region has a width within a range of 0.4 mm to 1.2 mm. In some embodiments, the peripheral landing area is defined by a shape having one or more control points within the peripheral landing area, the shape being defined by one of a spline, a polynomial, a conic section, an angled curve, and an angled non-curve.In some embodiments, an edge of the aft surface begins at the radially most peripheral portion of the peripheral landing zone and joins with the radially most peripheral portion of the anterior surface, and the edge of the aft surface is defined by an ellipse, a conic section, or a spline, hi some embodiments, the volume control zone and the secondary compression zone are defined by a single spline.

[0017] In general, one aspect of the present disclosure features a method for defining a contact lens to be manufactured for a patient's eye, comprising selecting, in accordance with a corneal topography of the patient's eye, a base radius of curvature of a central compressed region of the contact lens, a semi-meridian radial distance around the periphery of the central compressed region of the contact lens, an area of ​​a volume control region adjacent to the central compressed region, and a semi-chord radial distance of a secondary compressed region adjacent to the periphery of the volume control region that contacts the pre-treatment cornea of ​​the eye; determining the locations of a plurality of control points to define at least the width of the central compressed region, the shape of the volume control region that will produce a predetermined area between the region surface and the corneal surface to be treated, the semi-meridian radial distance of the secondary compressed region, and the inward angle of the apex of the secondary compressed region; and defining semi-meridians of the posterior surface of the contact lens in accordance with the plurality of control points.

[0018] Embodiments of the method may include one or more of the following features: Some embodiments comprise placing a first control point of the plurality of control points at a geometric center of the pre-treatment cornea corresponding to the geometric center of the contact lens; Some embodiments comprise determining a base radius of curvature according to subjective refraction of the eye and keratometry or topography measurements; selecting a half-chord radial distance of a second control point of the plurality of control points as a peripheral edge of the central compressed region; and setting a sagittal depth of the second control point of the plurality of control points at a sagittal depth of the selected base radius of curvature at the half-chord radial distance of the second control point of the selected plurality of control points when the first control point of the plurality of control points is in contact with the underlying pre-treatment cornea. Some embodiments include selecting a half-chord radial distance of a third control point of the plurality of control points to separate a first section of the volume control region from a second section of the volume control region that is peripheral to the first section of the volume control region, and setting a sagittal depth of the third control point of the plurality of control points to a distance equal to the distance of a lens having a predetermined diopter treatment target radius when placed on an average pre-treatment cornea. Some embodiments include selecting a half-chord radial distance of a fourth control point of the plurality of control points to be equal to the half-chord radial distance of an apex of a secondary compression region according to a desired mid-peripheral add position. Some embodiments include selecting a squeeze angle on the peripheral side of the second section of the volume control region, and positioning a fifth control point of the plurality of control points to define the squeeze angle together with the fourth control point of the plurality of control points. Some embodiments include determining the position of a sixth control point of the plurality of control points according to an area of ​​the volume control region selected according to the desired mid-peripheral add power. Some embodiments comprise determining a total diameter of the contact lens according to a corneal diameter of the pre-treatment cornea and determining a position of a seventh control point of the plurality of control points according to the total diameter of the contact lens. Some embodiments comprise determining an eighth control point of the plurality of control points that defines an interior of the landing zone that contacts the pre-treatment cornea according to a corneal topography of the eye and a desired radial distance from the seventh control point of the plurality of control points according to a desired radial width of the landing zone.Some embodiments comprise selecting a diameter of a ninth control point of the plurality of control points; selecting an area of ​​a peripheral relief zone between the secondary compression zone and the landing zone; and determining a sagittal depth of the ninth control point of the plurality of control points according to the selected area of ​​the peripheral relief zone or according to the target treatment in diopters.

[0019] The present disclosure will now be described in detail with respect to one or more various embodiments with reference to the accompanying drawings, which are provided for purposes of illustration only and depict merely typical, illustrative embodiments. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a plan view of the posterior surface of a contact lens in accordance with some embodiments of the technology of the present disclosure. [Figure 2] 1 illustrates semi-meridians defining the posterior surface of an exemplary contact lens in accordance with some embodiments of the disclosed technology. [Figure 3] 1 is a flowchart illustrating a general process for manufacturing contact lenses for corneal reshaping in accordance with some embodiments of the disclosed technology. [Figure 4A] 1 is a flowchart illustrating a general process for determining contact lenses for corneal reshaping in accordance with some embodiments of the disclosed technology. [Figure 4B] 1 is a flowchart illustrating a general process for determining contact lenses for corneal reshaping in accordance with some embodiments of the disclosed technology. [Figure 5] FIG. 1 illustrates a block diagram of an exemplary computer system upon which embodiments of the present disclosure may be implemented. DETAILED DESCRIPTION OF THE INVENTION

[0021] The drawings are not intended to be exhaustive or to limit the disclosure to the precise form disclosed.

[0022] Embodiments of the disclosed technology provide corneal refractive therapy (CRT) contact lenses for nighttime corneal reshaping and methods for defining CRT contact lenses using a geometric volume control method. This approach uses spline functions or other geometric shapes to determine the surface contour of the contact lens at predetermined control points or knots on the posterior surface of the lens, defined by a specified semi-chord radial distance from the center of the lens to the edge of the lens and a sagittal depth from a reference plane. Some embodiments use a corneal topography for each eye to determine the semi-meridian sagittal depth at each control point and apply an algorithm that enables empirical ordering and observational fitting of the eye for nighttime corneal reshaping. Embodiments of the disclosed technology ensure a central corneal radius change to correct pre-existing myopia, produce the desired mid-peripheral add power and mid-peripheral add position through empirical selection of the lens's base curvature radius, and empirically select the lens's surface elevation on each semi-meridian at multiple predetermined control points on the lens surface from the center of the lens to the edge of the lens.

[0023]

[0013] Figure 1 is a plan view of the posterior surface of a contact lens according to some embodiments of the disclosed technology. Referring to Figure 1, the posterior surface of the contact lens includes a central compression zone (CCZ), a first volume control zone (VCZR1), a second volume control zone (VCZR2), a secondary compression zone (SCZ), a peripheral relief zone (PRZ), and a landing zone (LZ). Each zone is described in detail below.

[0024] FIG. 2 illustrates semi-meridians defining the posterior surface of an exemplary contact lens according to some embodiments of the disclosed technology. In FIG. 2, the semi-meridians of the contact lens are shown as continuous solid lines with multiple curves and control points CP. Also shown in FIG. 2 is a dashed line depicting the pretreatment cornea. The contact lens and pretreatment cornea are plotted on a grid graduated in millimeters, but FIG. 2 is not to scale. It should be understood that the specific values ​​of the control points CP shown are merely exemplary, and that other semi-meridians of the contact lens or other contact lenses may have different values ​​of the control points CP. If the eye were rotationally symmetric, a contact lens could be manufactured using control points from only one semi-meridian. However, because the eye is not rotationally symmetric, a single contact lens could be manufactured using control points from multiple semi-meridians with different surface elevation dimensions.

[0025] Referring to FIG. 2, the center of the pre-treatment cornea and the center of the contact lens are located at the origin of the grid. In FIG. 2, the anterior surface of the pre-treatment cornea and the anterior surface of the contact lens (not shown) face downward toward the bottom of the grid. As practiced by those skilled in the art of contact lens design and manufacturing, the anterior surface of the contact lens can have a predetermined radius in the central optical zone to produce a predetermined lens power in conjunction with the posterior radius of the central region. The anterior optical zone can be spherical, aspheric, single-radius, or multi-radius designed to produce multifocal power. The periphery of the anterior surface can be designed to produce a constant thickness from the posterior surface or can be designed to have a different thickness from each corresponding posterior surface control point. The present contact lens includes nine control points CP1-CP2, one for each zone of the contact lens. However, in other embodiments, a different number of control points can be used.

[0026] The central compressive zone (CCZ) contacts the pre-treatment cornea at its center and extends from control point CP1 at the center of the semi-meridian to control point CP2, which in this example is located at a half-chord radial distance of approximately 2.5 mm.

[0027] Surrounding the central compression zone is a volume control zone extending to control point CP4, which in this example is located at a half-chord radial distance of approximately 4 mm. In this example, the volume control zone includes two sections. Volume control zone 1 (VCZR1) extends to control point CP3, which in this example is located at a half-chord radial distance of approximately 3 mm. Surrounding volume control zone 1 is volume control zone 2 (VCZR2), which includes control points CP6 and CP5 and extends to control point CP4. In this example, control points CP6 and CP5 are located at half-chord radial distances of approximately 3.4 mm and 3.8 mm, respectively.

[0028] Surrounding the second volume control zone is a secondary compression zone (SCZ), where the contact lens also contacts the pre-treatment cornea. Surrounding the secondary compression zone is a peripheral relief zone (PRZ), which includes control point CP9 and extends to control point CP8, which in this example is located at a half-chord radial distance of approximately 5 mm. In this example, control point CP9 is located at a half-chord radial distance of approximately 4.5 mm.

[0029] Surrounding the peripheral relief zone is the landing zone (LZ), where the contact lens also contacts the pre-treatment cornea. The landing zone extends to a control point CP7, which in this example is located at a half-chord radial distance of approximately 5.4 mm. The peripheral edge of the landing zone represents the edge terminus (ET) of the contact lens.

[0030] A spherical or aspherical base curve may be used for the central compression region. The volume control region, secondary compression region, peripheral relief region, and landing region may be configured using circumferentially varying spline functions or other geometric shapes to achieve the desired sagittal depth difference at predetermined control points along each semi-meridian. The elevation difference may be obtained by topographical measurements of the pre-treatment cornea at each control point on each semi-meridian of the cornea being treated. The elevation difference between a point on the posterior lens surface and each point on the pre-treatment corneal surface may utilize the axial distance from the lens surface to the corneal surface or the radial distance from the lens surface to the corneal surface. The axial distance forms a line parallel to the lens axis, while the radial distance is along a direction from the lens surface toward the center of rotation of the corneal surface of each eye. In a preferred embodiment, the axial distance from the lens surface to the pre-treatment corneal surface is used to calculate the elevation difference between the control points on the posterior lens surface and each point on the corneal surface. The edges of the lens can be adjusted to produce flat and rounded, flat and non-rounded, or non-flat and rounded lenses.

[0031] The disclosed contact lenses demonstrate improved centration, optimized reduction of refractive myopia in treated eyes, and additional refractive power and position of the mid-peripheral cornea after a given treatment. The volume control zone, along with the position and angle of the half-chord radial distance formed by the secondary compression zone, generates a force that creates additional refractive power and position in the mid-periphery. The peripheral relief zone allows the secondary compression zone to impinge on the corneal epithelium and redistribute it inward toward the volume control zone. A uniformly aligned landing zone provides a compressive force that creates central compression and compression within the secondary compression zone. The high degree of non-rotational symmetry of the landing zone, aligned with the pre-treatment corneal elevation difference along two or more semi-meridians, provides optimal compression, lens stability, and improved lens centration. A rim is added to the landing zone. The shape of the posterior contact lens surface is continuous and seamless to prevent graft-induced trauma. In one embodiment, cubic splines can be used with controlled placed knots at corresponding control points to produce a smooth, continuous, seamless surface at a predetermined angle inward from the secondary compression zone, with a predetermined area under each semi-meridian of the volumetric control zone.

[0032] The contact lens is seamless because each zone begins with a local slope at the end of the zone centrally relative to that zone. The spline knots of the volume control zones control the relative sagittal depth of the lens at predetermined control points along the posterior surface of the lens semi-meridians outside the central compression zone, and the spline control provides the surface shape. The most central portion of the spline is defined by the elevation and local slope at the chord of the optical zone junction, and the most peripheral portion is defined by the desired elevation at the next peripheral control point on each semi-meridian. The local slope of the most peripheral portion of the volume control zone is defined by a predetermined squeeze angle with an apex at the deepest point of the secondary compression zone. The most peripheral portion of the secondary compression zone is defined by the local slope of the most central portion of the peripheral relief zone, and the most peripheral portion of the peripheral relief zone is defined by the most central portion of the landing zone. The edge begins at the elevation of the most peripheral portion of the landing zone.

[0033] In some applications, lenses can be custom-designed for each eye. In other applications, a fitting set is provided from which lenses can be selected. An exemplary fitting set or kit might have one overall diameter (OAD, e.g., in the range of 10.5 mm to 11.5 mm), up to five base curve radii increments (BCRIs), a single optical zone diameter and one volume control zone width for each BCRI, up to five volume control zone areas for each volume control zone width, three secondary compression zone depths, one peripheral relief zone, and one landing zone. This fitting set might have 75 lenses (1 OAD x 5 BCRIs x 5 VCZ areas x 3 SCZ depths). A lookup table or computer application can be generated to suggest initial fitting set lenses based on input of subjective refraction, central keratometry, and corneal topography collected through standard clinical testing.

[0034] A preferred empirical method, in the absence of a fitting set and corneal topography, is to empirically design a first observation lens to be manufactured by predicting the base radius using subjective refraction and standard keratometry, predicting the first and second volume control zones using the treatment dose in diopters and average biometric data, predicting the secondary compression zone depth and standard peripheral relief zone height using the treatment dose and average biometric data, and predicting the local slope and sagittal depth of the central portion of the landing zone using the average biometric data. This first lens, empirically designed from clinical data, can serve as the observation lens for ordering the second lens. The empirically designed first observation lens is predicted to include non-rotational symmetry based on the average biometric data indicating asymmetry.

[0035] 3 is a flow chart illustrating a general process 300 for manufacturing contact lenses for corneal reshaping, in accordance with some embodiments of the disclosed technology. Elements of process 300 are shown in a sequence. However, one or more elements of the process may be performed in a different order, in parallel, omitted entirely, etc. Additionally, process 300 may include other elements in addition to those shown.

[0036] 3, process 300 may include, at 302, performing an eye clinical test. The clinical test may include determining unaided visual acuity, refraction, binocular visual acuity, peripheral refraction, ocular health, keratometry, corneal diameter, corneal topography, eyelid position, aperture size, pupillometry, and the like.

[0037] Process 300 may include selecting constants and calculating lens parameters at 304. The lens parameters may include base radius, optic zone diameter, total diameter, mid-peripheral add power, central half-chord radial distance of mid-peripheral add power, lens power, etc.

[0038] Process 300 may include, at 306, calculating the diameter and sagittal depth for control points on the posterior surface of the contact lens. The calculations may be based on average biometric data, measured corneal topography, a combination thereof, or the like, as described in more detail below. Following the calculations, control points may be calculated for the anterior surface, for example, using thickness rules or constants from one or more posterior control points to one or more anterior control points, incorporating the required anterior central radius of curvature(s) to produce the desired lens power(s), such as in the case of progressive optics.

[0039] The process 300 may include, at 308, generating a cutting file to manufacture the contact lens. For example, semi-meridians of the posterior surface of the contact lens, as shown in FIG. 1, may be calculated using control points. The semi-meridian surfaces may be generated using splines, geometric segments, combinations thereof, or the like. The contact lens may be manufactured using typical quality control manufacturing practices from standard extended-wear rigid gas permeable materials, or the like. For example, a polish-free computer numerically controlled lathe may be used to cut the contact lens. Following cutting, a contour inspection of the posterior surface of the contact lens may be performed to determine whether the finished posterior surface conforms to the intended shape.

[0040] Process 300 may include applying and evaluating a contact lens at 310, which may include taking an image of the contact lens on the patient's eye. The image may be analyzed to evaluate the relationship of the lens to the eye and measure lens centration. The evaluation may include determining hyperrefraction, measuring visual acuity, etc. Process 300 may conclude at 312 with prescribing contact lenses and performing one or more follow-up evaluations.

[0041] 4A and 4B are flowcharts of a general process 400 for determining contact lenses for corneal reshaping, in accordance with some embodiments of the disclosed technology. Elements of process 400 are shown in a sequence. However, one or more elements of the process may be performed in a different order, in parallel, omitted entirely, etc. Additionally, process 400 may include other elements in addition to those shown.

[0042] 4A, process 400 may include, at 402, placing a control point CP1 at the geometric center of the lens to coincide with the geometric center of the pre-treatment cornea. Process 400 may include, at 404, determining a base curve radius according to subjective refraction and keratometry of the treated eye, selecting a diameter for control point CP2 as the peripheral edge of the central compression zone CCZ, and setting a sagittal depth for control point CP2 at the sagittal depth of the selected base curve radius at the selected diameter for control point CP2.

[0043] At 406, process 400 may include selecting a diameter of control point CP3 to separate a first section of the volume control region from a second section of the volume control region peripheral to the first section of the volume control region, and setting a sagittal depth of control point CP3 at a predetermined diopter distance from the apical radius of the pre-treatment cornea. In one embodiment, the sagittal depth difference of CP3 from the cornea is constant and independent of the target treatment volume. In this embodiment, all treatment lenses have the same sagittal depth difference from the inferior cornea at CP3, regardless of the target treatment difference or the difference between the central corneal radius and the radius of the base curve of the treatment lens. The second section of the volume control region accommodates eyes with different mid-peripheral height differences, equalizing the area under each semi-meridian to control the location of the corneal power increase that occurs under that area, thereby improving lens centration. The circumferential equality of the area under each semi-meridian prevents the non-toric base curve and circumferential elevation difference of the volume control region from having a heavy bearing on the shallow semi-meridians of the pre-treatment cornea, and also prevents z-axis tilt and decentration toward the deep semi-meridians of the cornea, thereby eliminating the need for toric or double elevation fittings.

[0044] At 408, process 400 may include selecting the diameter or half-chord radial distance of control point CP4 for the secondary compression zone according to the desired location of mid-peripheral add power. The sagittal depth of the secondary compression zone SCZ at control point CP4 is a function of the sagittal height of the inferior pre-treatment cornea at control point CP4 (the apex of the zone). The posterior surface advances to the next control point CP9, which determines the height of the peripheral relief zone PRZ. In one embodiment, the height of control point CP9 from the inferior pre-treatment cornea is determined by the central treatment volume in diopters. For example, the height of control point CP9 from the inferior cornea may be equal to 6 μm per diopter of treatment. The peripheral relief zone then descends toward control point CP8. The elevation of control point CP8 corresponds to the measured elevation of the treatment cornea at the half-chord radial distance of the beginning of landing zone LZ. The half-chord radial distance of control point CP8 is determined by the half-chord radial distance of control point CP7 and the desired minimum width between control points CP8 and CP7. In one embodiment, the half-chord radial distance of control point CP7 is determined by the measured horizontal corneal diameter. For example, the lens diameter can be selected to be 90% of the measured corneal diameter, and the half-chord radial distance of control point CP7 is determined to be 45% of the corneal diameter. The desired half-chord width from control point CP8 to control point CP7 ranges from 0.8 mm to 1.6 mm. The limbus ET at control point CP7 is integrated into the sagittal depth of the lens at the most peripheral part of the landing zone LZ. The sagittal depth of control point CP7 is selected as a function of the predetermined limbal elevation from the inferior cornea at the desired half-chord radial distance of control point CP7 and the known eye contour.

[0045] The spline for the secondary compression zone SCZ can be calculated to begin with the local slope of the last control point CP5 of the volume control zone spline and produce an angle of incidence of the secondary compression zone SCZ on the inferior pre-treatment cornea (referred to herein as the squeeze angle (SA)) that optimizes tissue movement inward into the volume control zone. At 410, process 400 can include selecting a squeeze angle for the peripheral side of the second section of the volume control zone and positioning control point CP5 to define the squeeze angle with control point CP4. The angle can be measured from a line perpendicular to the lens axis through control point CP4, or it can be measured from the local slope of the inferior cornea at control point CP4. For example, the local slope of the pre-treatment cornea at control point CP4 can be measured as 28 degrees, and the desired angle between the pre-treatment cornea and the posterior lens surface can be 5 degrees. Thus, the predetermined angle generated by the horizontal line passing through control point CP5 and control point CP4 inward from the apex of control point CP4 can be reported as 33 degrees from the horizontal line.

[0046] Referring now to FIG. 4B, process 400 may include, at 412, selecting an area of ​​the volume control region according to a desired peripheral add power and determining a position of control point CP6 to produce the desired area of ​​the volume control region. The area of ​​the volume control region may be estimated as an approximation of the area of ​​the posterior surface of a second- or third-generation corneal reshaping lens with a target treatment of 3.00 diopters when the lens is placed on the pre-treatment cornea. Second- or third-generation CRT lenses are typically fitted with a radius approximately 1.00 diopters larger than the target treatment. Thus, the target or desired area of ​​the volume control region semi-meridian may be estimated according to the area of ​​a lens with a 4.00D larger radius of curvature on an average cornea with an average optical zone diameter, an average reverse curve or return zone width, and an average reverse curve radius or return zone depth. The target or desired total area at a single half-chord radial distance may include the entire volume control region from the center of the lens (control point CP1) to control point CP4, the entire volume control region from control point CP2 to control point CP4, or only the second section of the second control region from control point CP3 to control point CP4. For example, the area from control point CP2 to control point CP4 for a third or fourth generation CRT lens with an optic zone diameter of 5.0 mm, a reverse curve width of 1.5 mm, and a base curve radius of 4.00 diopters (approximately 0.8 mm longer than the radius of the pre-treatment cornea) is 1.58×10 4 μm 2 , or 0.0158 mm 2The desired area in the semi-meridian varies depending on the half-chord radial distance of the control points CP2, CP3, and CP4. The control point CP4 defines the half-chord radial distance of the midpoint of the mid-peripheral add power. The more central the mid-peripheral add power is desired in the lens, the shorter the half-chord radial distance of the control point CP4. The shorter the half-chord radial distance of the control point CP4, the smaller the area of ​​each volume control zone when the control points CP2 and CP3 are held constant. In one embodiment, the half-chord radial distance of the control point CP2 is kept equal to or greater than 1.5 mm, and the half-chord radial distance of the control point CP3 is kept equal to or greater than 2.2 mm. As the half-meridian radial distance of the control point CP4 decreases, the half-meridian radial distance of the midpoint of the post-treatment mid-peripheral add power decreases. For a given half-chord radial distance of the control point CP4, the larger the area of ​​the volume control zone, the higher the mid-peripheral add power. As can be seen, modulation of the semi-meridian radial distance of control point CP4 controls the radial location of the mid-peripheral add power, the area between the posterior lens surface and the pre-treatment cornea within the volumetric control region modulates the mid-peripheral add power, and the semi-meridian radial distance of control point CP6 modulates the shape of the mid-peripheral add power.

[0047] At 414, the process 400 determines the overall diameter of the contact lens according to the corneal diameter of the pre-treatment cornea, and determines the location of the control point CP7 according to the overall diameter of the contact lens.

[0048] At 416, process 400 may include determining control point CP8, which defines a landing zone LZ to contact the pre-treatment cornea according to the corneal topography of the eye and the location of control point CP7. The circumferential elevation characteristics of the secondary compression zone SCZ and landing zone LZ provide a uniform edge elevation in the circumferential direction, promoting improved centration and comfort. A semi-meridian sagittal depth control design may use different splines in one or more semi-meridians in one or more regions of the lens outside the optical zone. The amount of sagittal depth difference may be predetermined near a nominal value for a large number of normal eyes, or may be empirically determined using elevation data from corneal topography.

[0049] At 418, process 400 may include selecting a diameter for control point CP9, selecting an area for a peripheral relief region between the secondary compression region and the landing region, and determining a sagittal depth for control point CP9 according to the selected area for the peripheral relief region. In an alternative embodiment, the sagittal depth for control point CP9 is determined as a function of the treatment goal for each eye. As known to those skilled in the art, the corneal apex recedes approximately 6 μm per diopter gained in treatment. Control point CP9 may be positioned 6 μm per diopter from the inferior cornea. For example, if a 3.00D treatment goal is achieved, control point CP9 may be positioned 18 μm from the inferior corneal surface when control points CP1, CP4, and CP8 are positioned in contact with the corneal surface. It is understood that while a larger clearance is acceptable, a smaller clearance may interfere with treatment or require the entire lens surface from control points CP4 to CP7 to compress the cornea.

[0050] Table 1 below shows an example in which the posterior sagittal depth is determined given the semi-meridian corneal elevation at a control point at a semi-meridian radial distance according to a method of one embodiment of the present invention.

[0051] [Table 1]

[0052] At 420, process 400 may include defining semi-meridian semi-chord radial distances and sagittal depths of the posterior surface of the contact lens in response to control points CP1-CP9. Following definition of one or more semi-meridians, the contact lens may be manufactured, for example, as described above. The semi-meridian radial distances and corresponding depths of the control points are input to a computer program product that completes the required x, y, and z points across the entire lens surface.

[0053] The techniques of this disclosure are applicable not only to the corneal reshaping portion of hard corneal lenses, but also to the corneal reshaping portion of lenses with a diameter larger than the cornea, such as scleral contact lenses, hybrid contact lenses, and soft contact lenses. In lens embodiments with a diameter larger than the cornea, the edge does not connect to the anterior surface at control point CP7. Rather, the edge of the peripheral landing region connects to a subsequent peripheral region on the posterior surface that extends beyond the diameter of the cornea in at least one semi-meridian.

[0054] 5 illustrates a block diagram of an exemplary computer system 500 capable of implementing embodiments of the present disclosure. The computer system 500 includes a bus 502 or other communication means for communicating information and one or more hardware processors 504 coupled to the bus 502 for processing information. The hardware processors 504 may be, for example, one or more general-purpose microprocessors.

[0055] Computer system 500 also includes a main memory 506 (such as random access memory (RAM), cache, and / or other dynamic storage device) coupled to bus 502 for storing instructions and information executed by processor 504. Main memory 506 may also be used for storing temporary variables or other intermediate information during execution of instructions executed by processor 504. The instructions stored on such storage media accessible to processor 504 make computer system 500 a specialized machine customized to perform the operations specified in the instructions.

[0056] Computer system 500 further includes a read-only memory (ROM) 508 or other static storage device coupled to bus 502 for storing static information and instructions for processor 504. A storage device 510, such as a magnetic disk, optical disk, USB thumb drive (flash drive), etc., is provided and coupled to bus 502 for storing information and instructions.

[0057] Computer system 500 may be coupled via bus 502 to a display 512 (such as a liquid crystal display (LCD) or touch screen) for displaying information to a computer user. An input device 514 (such as an alphanumeric or other keyboard) is coupled to bus 502 for communicating information and command selections to processor 504. Another type of user input device is a cursor control 516 (such as a mouse, trackball, cursor direction keyboard, etc.) for communicating instructional information and command selections to processor 504 and for controlling cursor movement on display 512. In some embodiments, the same instructional information and command selections as cursor control may be achieved through receiving touches on a touch screen without a cursor.

[0058] Computer system 500 may include a user interface module implementing a GUI, which may be stored on a mass storage device as executable software code executed by a computing device. Such modules and other modules may include, for example, components such as software components, object-oriented software components, class components, task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, variables, etc.

[0059] As generally used herein, terms such as "component," "engine," "system," "database," and "data store" may refer to logic implemented in hardware or firmware, or to a collection of software instructions (which may have entry and exit points) written in a programming language (e.g., Java, C, C++, etc.). Software components may be compiled and linked into an executable program, installed in a dynamic link library, or written in an interpreted programming language (e.g., BASIC, Perl, Python, etc.). Software components may be callable by other components or by themselves, and / or may be invoked in response to detected events or interrupts. Software components configured to run on a computing device may be provided on computer-readable media (CD, DVD, flash drive, magnetic disk, other tangible media) or as a digital download (which may originally be stored in a compressed or installable format that requires installation, decompression, or decoding before execution). Such software code may be partially or completely stored in the memory device of the computing device for execution by the computing device. Software instructions may be implemented in firmware, such as in an EPROM. It should also be understood that hardware components may consist of connected logic units such as gates and flip-flops, and / or may consist of programmable units such as programmable gate arrays or processors.

[0060] Computer system 500 may perform the methods of the present disclosure using customized hardwired logic, one or more ASICs or FPGAs, firmware, and / or program logic, either dedicated to computer system 500 or in combination with other programming of the computer system. According to one embodiment, the methods of the present disclosure are performed by computer system 500 in response to processor 504 executing one or more sequences of one or more instructions contained in main memory 506. Such instructions may be read into main memory 506 from another storage medium, such as storage device 510. Execution of the sequences of instructions contained in main memory 506 causes processor 504 to perform the process steps of the present disclosure. In alternative embodiments, hardwired circuitry may be used in place of or in combination with software instructions.

[0061] As used herein, terms like "non-transitory media" refer to media that store data and / or instructions that cause a device to operate in a specific manner. Such non-transitory media can include non-volatile media and / or volatile media. Non-volatile media include, for example, optical and magnetic disks, such as storage device 510. Volatile media include dynamic memory, such as main memory 506. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tape, other magnetic data storage media, CD-ROMs, other optical data storage media, physical media with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, NVRAM, other memory chips or cartridges, and networked versions thereof.

[0062] Non-transitory media are distinct from, but may be used in conjunction with, transmission media. Transmission media involves transmitting information between non-transitory media. For example, transmission media include coaxial cables, copper wire, fiber optics, and the wires that comprise bus 502. Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave or infrared data communications.

[0063] Computer system 500 also includes a network (communications) interface 518 coupled to bus 502. The network interface 518 provides a two-way data communication coupling of one or more network links to one or more local networks. For example, communication interface 518 may be an Integrated Services Digital Network (ISDN) card, a cable modem, a satellite modem, or a modem providing a communications connection to a corresponding type of telephone line. In another example, network interface 518 may be a local area network (LAN) card providing a data communication connection to a compatible LAN (or WAN components communicating across the WAN). Wireless links are also possible. In such an embodiment, network interface 518 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0064] A network link typically provides data communication through one or more networks to other data devices. For example, a network link may provide a connection through a local network to a host computer or to data equipment operated by an ISP (Internet Service Provider). The ISP, in turn, provides data communication services through the world wide packet data communication network (now commonly referred to as the "Internet"). Both local networks and the Internet use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and on the network link through communication interface 518, which carry the digital data to and from computer system 500, are exemplary forms of transmission media.

[0065] Computer system 500 may send messages and receive data, including program code, through the network(s), network link, and communication interface 518. In the Internet example, a server might transmit code for a requested application program through the Internet, an ISP, a local network, and communication interface 518.

[0066] The received code may be executed by processor 504 as it is received, and / or stored in storage device 510, or other non-volatile storage for later execution.

[0067] Each of the processes, methods, and algorithms described above may be performed fully or partially automatically in code components executed by one or more computer systems or computer processors, including computer hardware. One or more computer systems or computer processors may also operate to support the execution of related operations in a "cloud computing" environment or as a service-as-a-software (SaaS). The processes and algorithms may be partially or fully implemented in application-specific circuitry. The various features and processes described above may be used independently or combined in various ways. Various combinations and subcombinations are within the scope of the present disclosure, and certain method or process blocks may be omitted in some embodiments. The methods and processes of the present disclosure are not limited to a particular order, and the associated blocks or conditions may be performed in other orders, in parallel, or in other ways, as appropriate. Blocks or conditions may be added or removed from the exemplary embodiments of the present disclosure. Execution of certain operations or processes may be distributed across multiple computer systems or computer processors, rather than residing solely within one device, and may be distributed across multiple devices.

[0068] Circuitry as used herein may be implemented using any form of hardware or a combination of hardware and software. For example, one or more processors, controllers, ASICs, PLAs, PALs, CPLDs, FPGAs, logic components, software routines, or other mechanisms may be implemented to provide the circuitry. In such implementations, various circuits of the present disclosure may be implemented as separate circuits, or functions and features of the present disclosure may be shared in part or in whole by one or more circuits. Although various features and elements of functionality may be separately described and claimed as individual circuits, these features and functions may be shared by one or more common circuits, and this does not require or imply that separate circuits are required to implement such features or functions. When circuitry is implemented in whole or in part using software, such software may be implemented to operate on a computing or processing system capable of performing the functions described with respect to computer system 500, etc.

[0069] The term "or" as used herein may be interpreted as either inclusive or exclusive. Furthermore, singular references do not exclude plural references. Conditional references such as "can," "could," "could," "might," and the like generally convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not, unless otherwise specified or understood within the context in which they are used.

[0070] Terms and phrases used in this application are to be construed as open-ended and not limiting, unless otherwise specified. Terms such as "conventional," "traditional," "usual," "standard," and "known" do not limit the subject matter to those available for a given period or at a given time, but rather include conventional, traditional, usual, or standard techniques that are available or may be known now or in the future. The presence of broadening terms such as "one or more," "at least," and "without limitation" does not imply that a narrowing of the scope is intended or required in the absence of such broadening terms.

Claims

1. 1. A contact lens for reshaping a pre-treatment cornea of ​​a patient's eye, comprising: an anterior surface and a posterior surface having a semi-meridian; The semi-meridian is a central compressive region in contact with the pre-treatment cornea; a volume control region surrounding the central compression region; a secondary compression region around the volume control region and in contact with the pre-treatment cornea; a peripheral relief region around the secondary compression region; a landing area around the peripheral relief area that contacts the pre-treatment cornea; a peripheral edge of said landing area.

2. The contact lens of claim 1 wherein the radius of the central compressed region is spherical.

3. The contact lens of claim 1 wherein the radius of the central compressed region is aspheric.

4. 10. The contact lens of claim 1, wherein the diameter of the central compressed region is between 3.0 mm and 7.0 mm.

5. the volumetric control region is defined by four or more geometric control points connected by one of a spline, a polynomial, and a combination of conic and non-conic sections; the second geometric control point is in the vicinity of the first geometric control point; a third geometric control point is located in the periphery of the second geometric control point; The contact lens of claim 1 , wherein a fourth geometric control point contacts the pre-treatment cornea, the fourth geometric control point being peripheral to the third geometric control point.

6. 6. The contact lens of claim 5, wherein the first geometric control point of the volume control region is located within a range of 5 μm to 80 μm away from the pre-treatment cornea in the z-axis direction.

7. 6. The contact lens of claim 5, wherein the second geometric control point of the volume control region is positioned away from the pre-treatment cornea in a z-axis direction to define a predetermined area between the posterior surface and the pre-treatment cornea within the volume control region.

8. 6. The contact lens of claim 5, wherein a third geometric control point of the volumetric control region is positioned to define a predetermined angle between (i) a line connecting the third geometric control point and the fourth geometric control point and (ii) a horizontal line passing through the fourth geometric control point.

9. 6. The contact lens of claim 5, wherein the semi-chord radial distance of the fourth geometric control point is in the range of 2.6 mm to 5.2 mm.

10. The contact lens of claim 1, wherein the secondary compression region has a width in the range of 0.2 mm to 0.8 mm.

11. 10. The contact lens of claim 1, wherein the secondary compression region is defined by a shape having one or more control points within the secondary compression region, the shape being defined by one of a spline, a polynomial, and a convex conic section.

12. 10. The contact lens of claim 1, wherein the peripheral relief region is defined by one or more control points spaced apart in the z-axis direction from the pre-treatment cornea by at least 6 μm per diopter to reduce central refractive error.

13. The contact lens of claim 1 , wherein the peripheral relief region has a width of between 0.4 mm and 1.2 mm.

14. 10. The contact lens of claim 1, wherein the landing area is defined by a shape having one or more control points within the landing area, the shape being defined by one of a spline, a polynomial, a conic section, an angled curve, and an angled non-curve.

15. an edge of the trailing surface beginning at a radially most peripheral portion of the landing area and joining the radially most peripheral portion of the leading surface; The contact lens of claim 1 , wherein the edge of the posterior surface is defined by an ellipse, a conic section, or a spline.

16. The contact lens of claim 1 , wherein the volume control region and the secondary compression region are defined by a single spline.

17. 1. A method for determining a contact lens to be manufactured for an eye of a patient, comprising: selecting, according to a corneal topography of the patient's eye, a base radius of curvature of a central compressed region of the contact lens, a semi-meridian radial distance around the periphery of the central compressed region of the contact lens, an area of ​​a volume control region adjacent to the central compressed region, and a semi-chord radial distance of a secondary compressed region adjacent to the periphery of the volume control region that contacts the pre-treatment cornea of ​​the eye; determining the locations of a plurality of control points that define at least the width of the central compression zone, the area of ​​the volumetric control zone, the semi-meridian radial distance of the secondary compression zone, and the inward angle of the apex of the secondary compression zone; determining a semi-meridian of the posterior surface of the contact lens according to the plurality of control points.

18. 18. The method of claim 17, further comprising placing a first control point of the plurality of control points at a geometric center of the pre-treatment cornea corresponding to a geometric center of the contact lens.

19. determining the base radius of curvature according to subjective refraction of the eye and keratometry; selecting a half-chord radial distance of a second control point among the plurality of control points as a peripheral edge of the central compression region; 20. The method of claim 18, further comprising: setting a sagittal depth of a second control point of the plurality of control points at a sagittal depth of the base surface radius at a half-chord radial distance of a second control point of the selected plurality of control points when a first control point of the plurality of control points is in contact with the inferior pre-treatment cornea.

20. selecting a half-chord radial distance of a third control point among the plurality of control points so as to separate a first section of the volume control region from a second section of the volume control region that is located around the first section of the volume control region; 20. The method of claim 19, further comprising: setting a sagittal depth of a third control point of the plurality of control points at a distance equal to the distance of a lens having a predetermined diopter treatment target radius when placed on an average pre-treatment cornea.

21. 21. The method of claim 20, further comprising selecting a half-chord radial distance of a fourth control point of the plurality of control points to be equal to a half-chord radial distance of an apex of the secondary compression region according to a desired mid-periphery addition position.

22. selecting a squeeze angle on the peripheral side of the second section of the volume control region; 22. The method of claim 21, further comprising: positioning a fifth control point of the plurality of control points to define the squeeze angle together with a fourth control point of the plurality of control points.

23. 23. The method of claim 22, further comprising determining a position of a sixth control point of the plurality of control points according to an area of ​​the volumetric control region selected according to a desired mid-peripheral add power.

24. determining an overall diameter of the contact lens according to a corneal diameter of the pre-treatment cornea; 24. The method of claim 23, further comprising determining a position of a seventh control point of the plurality of control points according to an overall diameter of the contact lens.

25. 25. The method of claim 24, further comprising determining an eighth control point of the plurality of control points that defines an interior of a landing zone that contacts the pre-treatment cornea according to a corneal topography of the eye and a desired radial distance from a seventh control point of the plurality of control points according to a desired radial width of the landing zone.

26. selecting a diameter of a ninth control point from the plurality of control points; selecting an area of ​​a peripheral relief region between the secondary compression region and the landing region; 26. The method of claim 25, further comprising determining a sagittal depth of a ninth control point of the plurality of control points according to an area of ​​the selected peripheral relief region or according to a target treatment in diopters.

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