Ophthalmic Instrument Alignment System

Abstract

A method and apparatus for aligning an ophthalmic instrument with respect to an eye is disclosed, including aligning a keratometer with respect to a patient's eye. Other features of the method and apparatus of the present invention are described further herein.

Description

[Technical field]

[0001] The present disclosure relates to methods and apparatus for aligning an ophthalmic instrument with respect to an eye. More particularly, but not exclusively, the present disclosure relates to aligning aesthesiometers with respect to a patient's eye. [Background technology]

[0002] Many ophthalmic instruments must be precisely aligned with the eye. For example, ophthalmic instruments such as keratometric aesthesiometers are used to measure the corneal sensitivity of the surface of the eye. Traditionally, corneal sensitivity has been measured using a contact method, which can provide inaccurate measurements. One example of such an instrument uses a single nylon thread to provide varying forces on the cornea. Another example of a less invasive method for measuring corneal sensitivity is the non-contact air puff technique (pneumatic aesthesiometer). In this technique, the pressure or flow rate of an air puff blown on the cornea can be changed until the patient detects a sensation.

[0003] The cornea protrudes outward from the eyeball and has a radius of curvature that is generally independent of the curvature of the sclera. The shape of the cornea and its position relative to the eye socket can vary from patient to patient. This can make it difficult to align instruments to the cornea. Movement of the eye during the alignment process can result in misalignment of the ophthalmic instrument relative to the eye.

[0004] In conventional pneumatic esthesiometers, the nozzle position is adjusted by the examiner using two camera systems: one to observe the distance of the nozzle from the cornea (z direction) and the other to position the nozzle at the center of the cornea (x, y direction). Positioning the cameras can be time consuming, especially when multiple instruments need to be set up. It requires the patient to be still and have at least one eye open, which can be uncomfortable for the patient, and is a potential source of variability if the positioning is not identical from visit to visit. The integration of two camera systems to detect eye position is spatially and computationally demanding and can increase the complexity of the detection system and limit the minimum size of the system. Summary of the Invention

[0005] It is an object of the present disclosure to provide improved methods and apparatus for aligning an ophthalmic instrument with respect to an eye.

[0006] According to a first aspect of the present disclosure, there is provided a method having the features set forth in claim 1 below.

[0007] According to a second aspect of the present disclosure there is provided an apparatus having the features as recited in claim 13 below.

[0008] According to a third aspect of the present disclosure there is provided an ophthalmic apparatus having the features as recited in claim 19 below.

[0009] Preferred but optional (but not essential) features of the present disclosure are set out in the following description and dependent claims.

[0010] Of course, it will be understood that features described in relation to one aspect of the present disclosure may be incorporated in other aspects as well, for example a method of the present disclosure may incorporate any of the features described with reference to an apparatus of the present disclosure, and vice versa.

[0011] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying schematic drawings. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 illustrates several steps for aligning an ophthalmic instrument with respect to an eye, according to a first embodiment.

[0013] [Diagram 2] FIG. 2 illustrates diagrammatically an apparatus for aligning an ophthalmic instrument with respect to an eye, according to a second embodiment.

[0014] [Diagram 3] FIG. 3 shows a partial perspective view of an apparatus for aligning an ophthalmic instrument with respect to an eye, according to a third embodiment.

[0015] [Figure 4a] Figures 4a and 4b show in cross section a beam of light directed towards and reflected from an eye according to a fourth embodiment. [Figure 4b] 4a and 4b show in cross section a beam of light directed towards and reflected from an eye according to a fourth embodiment.

[0016] [Figure 5a] FIG. 5a shows a front view of a detector arrangement according to a fifth embodiment.

[0017] [Figure 5b] FIG. 5b shows a front view of the detector arrangement according to the sixth embodiment.

[0018] [Figure 6a] FIG. 6a shows graphical data representative of signals received at a detector according to a sixth embodiment for aligning an ophthalmic instrument along the x and y axes.

[0019] [Figure 6b]FIG. 6b shows graphical data representative of signals received at a detector according to a sixth embodiment for aligning an ophthalmic instrument along the z-axis.

[0020] [Figure 7] FIG. 7 illustrates diagrammatically an apparatus for aligning an ophthalmic instrument, according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In a first aspect, the present disclosure provides a method of aligning an ophthalmic instrument with respect to an eye, the method comprising directing a beam of light from the ophthalmic instrument towards the eye, obtaining measurements of reflections of the light reflected from the eye at a plurality of positions around the beam, determining a position of the ophthalmic instrument with respect to the eye from the measurements, and moving the ophthalmic instrument with respect to the eye from the determined position to a desired position.

[0022] The method provides an improved and simpler method of aligning an ophthalmic instrument with respect to a patient's eye as compared to conventional instruments. The method eliminates the need for multiple separate systems, such as cameras and light sources, and allows an examiner to efficiently align an ophthalmic instrument with a patient's eye.

[0023] The ophthalmic instrument may be a keratometric aesthesiometer. The ophthalmic instrument may be positioned in front of the eye along the direction of the eye's optical axis. Ophthalmic examinations, particularly those related to corneal sensitivity, require a high level of precision. The method may reduce the time required to align the instrument with the eye and may provide continuous monitoring of the eye's position, increasing the precision of the alignment. Reducing the time required to align the ophthalmic instrument with the eye allows examiners (such as optometrists or ophthalmologists) to spend more time assessing patients.

[0024] The method may include aligning an ophthalmic device with respect to a center of a cornea of ​​an eye. The size and structure of the cornea of ​​an eye may vary from patient to patient. The method provides an improved method of aligning an ophthalmic device with respect to a center of the cornea and at a predetermined distance from the cornea.

[0025] Before measurements are taken, the examiner may manually align the ophthalmic instrument to the center of the eye's cornea, which is visible to the examiner and may serve as a reference point for initially aligning the ophthalmic instrument to the patient's eye.

[0026] The beam of light may be a collimated beam of light. The diameter of the beam of light will depend on the collimator. The beam may have a diameter of 1 mm. The diameter of the beam may be between 0.1 and 10 mm. The diameter of the beam may be smaller than the diameter of the collimator.

[0027] The method may include measuring an intensity of light reflected from the eye at a plurality of positions around the beam. The intensity of the light reflected from the eye is used to determine a position of the ophthalmic instrument relative to the eye. The reflected light may be reflected from the cornea of ​​the eye. As previously mentioned, if the area of ​​interest is the cornea of ​​the eye, the beam of light may be sized to be limited to a region of the cornea, and light may be reflected only from the cornea.

[0028] Measurement of the reflected light may determine the position of the ophthalmic instrument in three dimensions, i.e., in the z-axis, which is defined as the direction of the optical axis of the eye, and in the x- and y-axes, which define a plane perpendicular to the optical axis of the eye. The x- and y-axis positions of the ophthalmic instrument relative to the eye may be determined independently of the z-axis position of the ophthalmic instrument relative to the eye.

[0029] Light may be reflected directly from the eye. Light incident on the surface of the eye may be reflected back along the direction of the incident light beam. In a perfect arrangement where the cornea of ​​the eye is perfectly convex and the instrument is precisely aligned to the center of the cornea, if the beam of light is infinitesimally narrow and incident on a very small point on the cornea, the light will reflect back exactly along the direction of the beam. In reality, even with perfect alignment, the incident light beam has a finite diameter and a range of angles of incidence on the cornea, so light will reflect off of a convex surface at a range of angles relative to the axis of the incident light beam.

[0030] The reflected light may be measured at, for example, three, four, five, six, seven, eight, or more than eight locations around the beam of light. The locations may be distributed circumferentially around the beam of light. For example, if there are four locations around the beam of light at which light is measured, they may be above, below, to the left, and to the right of the beam of light.

[0031] The reflected light may be measured at positions symmetrically disposed around the beam of light. For example, the reflected light may be measured at positions above and below the beam of light, and / or at positions to the left and right of the beam of light, each position disposed at a 90 degree angle relative to each other. Preferably, when the instrument is correctly aligned to the eye, the reflected light measurements are symmetrically distributed across the positions. This is advantageous as it may provide a guide to aligning the instrument to the eye when there is any imbalance in the light distributed at symmetrical positions around the beam of light.

[0032] Determining the position of the ophthalmic instrument relative to the eye may be performed by calculating the difference in the measured light received at each position. The position of the ophthalmic instrument relative to the eye in the x-axis and y-axis may be determined by comparing the light intensity at two diametrically opposed positions. For example, the position of the ophthalmic instrument relative to the eye along the x-axis may be determined by calculating the difference in the light intensity measured on either side of the beam of light, e.g., to the left and right of the beam of light, at positions 180° from each other. The position of the ophthalmic instrument relative to the eye along the y-axis may be determined by calculating the difference in the light intensity measured above and below the beam of light.

[0033] Determining a position of the ophthalmic instrument relative to the eye may include calculating a total amount of incident light received at a plurality of positions. The total amount of light incident at the plurality of positions may provide position information along a z-axis of the ophthalmic instrument relative to the eye.

[0034] The ophthalmic device may be moved in a direction that equalizes or tends to equalize measurements received around the beam. For example, if the reflected light measurements detected by the detector are greater (e.g., of higher intensity) at a location above the light beam than at a location below the light beam, the ophthalmic instrument may be adjusted relative to the eye so that the reflected light measurements at those opposing locations are approximately equal (e.g., within 10%, within 5%, within 1%, etc.).

[0035] The method may include providing instructions to move the ophthalmic instrument relative to the eye. There may be a control actuator configured to receive the instructions and move the instrument relative to the eye. The method may include instructing the patient to move their head / eyes relative to the ophthalmic instrument. There may be a display or other visible light source that may provide instructions in the form of a signal to the patient. The method may include providing instructions to an examiner. There may be a user interface configured to receive the instructions and display the instructions to the examiner, for example via a software display. The examiner may manually move the position of the ophthalmic instrument relative to the eye. The examiner may instruct the patient to move their head / eyes relative to the ophthalmic instrument. For example, they may explain the instructions verbally.

[0036] The method may include using a camera to verify longitudinal alignment of the ophthalmic device relative to the eye. The camera may be positioned to the side of the patient's eye at a 90° angle relative to the direction of the light beam. The method may include capturing an image of the eye. The image may be used to determine the position of the eye and assist in the process of aligning the ophthalmic device relative to the eye.

[0037] In a second aspect, the present disclosure provides an apparatus for aligning an ophthalmic instrument with respect to an eye, the apparatus comprising: a collimated light source configured to be directed at an eye through an aperture, a number of detectors arranged around the aperture to measure light reflected from the eye, and a control unit configured to determine a position of the ophthalmic instrument with respect to the eye and move a relative position of the ophthalmic instrument and the eye from the determined position to a desired position.

[0038] The light may be infrared. The light source may be an infrared light emitting diode (LED). In some embodiments, the light source may be visible light. Although, to obtain measurements of the cornea of ​​the eye using visible light, in some circumstances high intensity visible light may be required for the light to reflect off the cornea, which may be dangerous to other parts of the eye. The use of infrared light may provide greater safety instead of using high intensity visible light, and may also improve the amount of light reflected off the eye, providing a quicker measurement of the position of the ophthalmic instrument relative to the eye.

[0039] The light source may be a low intensity infrared light source, which may reduce the risk of heating the corneal surface and / or other parts of the eye.

[0040] The device may include multiple light sources. Each light source may emit a different frequency of light, for example there may be infrared LEDs and visible LEDs. Other light sources known to those skilled in the art may also be used. A visible light source may be combined with an infrared light source to improve alignment of the ophthalmic instrument to the eye. In a healthy eye, the cornea is transparent to visible light. A low intensity visible light source may provide a signal to the patient to center the eye to the ophthalmic instrument. The visible light may have different colors to provide a guide to the patient to position the eye. For example, there may be red, yellow, and green lights to indicate if the eye is too close, too far, or in the correct position to the ophthalmic instrument. The light may provide special information by changing colors, or by changing the amplitude of the light or a special pattern (e.g. a flashing light). The light may be a simple point from the user's perspective and may be used as a fixed target. This may be an LED light source, in which case the light may be incident on the retina through a lens or series of lenses (a simple LED without a lens may be viewed as an unfocused dot on the retina). In other embodiments, a mask may be imaged onto the retina through a lens or series of lenses, which may be illuminated by one or more LEDs of one or more different colors, in other embodiments, an LCD, OLED, or other self-emissive display may be used with a lens or series of lenses to focus the display on the retina. Alternatively, there may be other signal sources, such as an audible sound, to assist the patient in aligning the eye with the ophthalmic instrument.

[0041] The aperture through which the light is directed may be an elongated tube. The aperture may be connected to a light source or may be fixed. The aperture may have an entrance where the light enters and an exit where the light exits. The aperture is positioned so that the exit is close to the surface of the eye. The exit of the aperture may be positioned, for example, at a distance of 0.5 mm to 50.0 mm from the surface of the eye. The aperture may be connected to an ophthalmic instrument. The aperture may be part of an ophthalmic instrument, for example, the aperture may be the nozzle of a pneumatic esthesiometer through which air is directed to the eye.

[0042] The light may be collimated at the light source. There may be optics that collimate the light. The nozzle of the pneumatic sensometer may be configured to direct and collimate the light.

[0043] The diameter of the aperture may be, for example, between 0.1 and 6.0 mm.

[0044] The aperture may be aligned with the cornea of ​​the eye. The aperture may be positioned along the optical axis of the eye.

[0045] The device may include at least three detectors, for example, the detectors may be positioned at angles of 120° from each other around the aperture. The device may include more than three detectors. The device may include between 3 and 10 detectors positioned around the aperture.

[0046] The detectors may be symmetrically positioned around the aperture. Symmetrically positioned detectors provide a better measurement of the distribution of light reflected from the eye. Measurements of reflected light may be used to determine the position of the ophthalmic instrument relative to the eye in three dimensions, i.e., in the z-axis and / or in the x- and y-axes. The position of the ophthalmic instrument relative to the eye along the x- and y-axes may be calculated by the imbalance in the intensity of light incident on diametrically opposed detectors. For example, measurements at detectors positioned above and below the aperture may provide the y-axis position of the ophthalmic instrument relative to the eye. By measuring the change in the radial distribution of reflected light at the detectors, the position of the ophthalmic instrument relative to the eye along the z-axis may be determined. In some embodiments, increasing the number of detectors distributed circumferentially and radially around the aperture may provide a more accurate measurement of the x-, y- and z-axis positions of the ophthalmic instrument.

[0047] The detector may be a photodiode. The detector may be an infrared detector. It will be understood that other detectors known to those skilled in the art may also be used. There may be different detectors to detect different frequencies of light. For example, there may be a first set of detectors for infrared detection arranged circumferentially around the aperture, and a second set of detectors for visible light detection arranged circumferentially (further) around the first set of detectors.

[0048] The detector may be located away from the exit of the aperture along the direction of the optical axis. The detector may be positioned a distance away from the eye for optimal detection and distribution of light. The detector may be mounted on a plate. The plate may be circular and may have a central hole so that the incident light is directed from the light source to the eye. The central hole of the plate may be configured to fit around a nozzle of an ophthalmic instrument. The plate may be a sensor printed circuit board (PCB). The detector may be mounted on the PCB.

[0049] The control unit may include a main controller board. The control unit may be connected to the detector to receive the detected signal. The control unit may determine the position of the ophthalmic instrument relative to the eye.

[0050] The devices described herein may include a computing system that is part of a control unit 50 (illustratively) for controlling the detectors and other functions described herein. The computing system may include, for example, a general-purpose processor, a digital signal processor (DSP) that serially processes digital signals, a microprocessor, an application specific integrated circuit (ASIC), an integrated circuit composed of logic elements, a field programmable logic array (FPGA), or other integrated circuits (ICs) or hardware components for performing one or more of the individual method steps and apparatus functions described herein. The computing system further includes a memory that stores data processing programs (software) that may be executed on the hardware components to perform the method steps. The computing system further includes a user interface as described herein. The user interface may include hardware, software, firmware, or a combination thereof to allow a user to communicate with the computing system and send commands (instructions). For example, the user interface may include, but is not limited to, a display, a touch screen display, a keyboard, a keypad, a mouse, a virtual reality interface, an augmented reality interface, a voice command interface, one or more speakers, one or more microphones, a combination thereof, and the like.

[0051] The control unit (e.g., 50) may include a processor, microprocessor, central processing unit (CPU), computer, or other processing device. The control unit may have multiple processors, comparators, regulators, logic circuits, and similar components, as will be appreciated by those skilled in the art. The control unit may be a component of a central control unit. The central control unit may have a data processing unit (e.g., microprocessor) on which a data processing program (e.g., software) may be executed. The control unit may be operated by a remote device. The remote device may include a mobile communication device, a mobile phone, a smartphone, a tablet, a smart watch, a physician network computer, a laptop computer, a desktop computer, a remote microprocessor, a remote central processing unit, combinations thereof, and the like.

[0052] The control unit may have a user interface. The user interface may present a signal measured from the reflected light to provide the position of the ophthalmic instrument relative to the eye. For example, the control unit may provide position information of the ophthalmic instrument relative to the eye on the user interface to provide the instructor with relevant information to manually move the ophthalmic instrument to a desired position. The information may be presented as images, graphic data, visual or audio cues such as flashing lights or beeps, etc.

[0053] The control unit may be connected to the actuator. The actuator may be configured to move the detector and / or the plate. The control unit may be connected to multiple actuators, one actuator may be connected to the ophthalmic instrument. The control unit may instruct the actuator to move the ophthalmic instrument from the determined position to a desired position. The determined position may already be the desired position, in which case the ophthalmic instrument remains stationary.

[0054] A control unit may be connected to the light source. The control unit may control the light intensity, beam size, or frequency. For example, if the detected signal is weak, the control unit may increase the intensity of the infrared light. If the detected position is the desired position, the control unit may instruct the visible light source to transmit a light beam of a particular color (e.g., green) to signal that the desired position has been achieved.

[0055] The apparatus is capable of carrying out the method steps according to the first aspect of the present disclosure.

[0056] The device may include a camera. The camera may be positioned to the side of the patient's eye at a 90° angle to the direction of the light beam. The camera may capture an image of the eye, which may be used to assist in the alignment of the ophthalmic instrument to the eye. The camera may be connected to a control unit. The control unit may have a user interface that displays the images. The camera may capture multiple images and provide real-time eye position information. The images may be displayed or printed to assist in the process of aligning the ophthalmic instrument to the eye.

[0057] According to a third aspect, an ophthalmic instrument is disclosed that includes the device described in the second aspect, the ophthalmic instrument may be an aesthesiometer. The aesthesiometer may have an elongated nozzle for the passage of air. The nozzle may be configured to direct light from a light source to the eye.

[0058] Other exemplary embodiments are described in further detail with reference to FIGS.

[0059] FIG. 1 shows the steps of aligning an ophthalmic device to an eye. There is a first step 1 of first aligning the ophthalmic device to the eye, preferably to the center of the cornea of ​​the eye. When the patient's eye is open, the cornea of ​​the eye needs to be visible to the examiner. The alignment can be performed by the examiner. Alternatively, the alignment can be performed by an actuator commanded by a control unit.

[0060] There is a second step 2 of directing a beam of light from the ophthalmic instrument to the eye. The beam of light is approximately collimated and is preferably infrared (IR).

[0061] There is a third step 3 of measuring the light reflected from the cornea of ​​the eye at a number of positions around the beam. The incident light beam may be a substantially circular light beam with an associated diameter. The curvature of the cornea of ​​the eye may be approximated as a convex surface that reflects light away from the direction of the incident light beam. In some embodiments, it is preferred to have at least three positions around the light beam. At each position there is a detector, for example a photodiode, or any other detector capable of detecting IR light. The detector may measure the intensity of the reflected light at each position.

[0062] The method includes a fourth step 4 of determining the position of the ophthalmic instrument relative to the eye by comparing the distribution of reflected light over a number of positions. By comparing the signals received at each position around the beam of light, the position of the ophthalmic instrument relative to the eye can be determined. Preferably, the detectors are positioned equidistantly along the z-axis symmetrically around the beam, for example, four detectors may be positioned at 90° angles to each other around the beam, the (four) detectors forming (four) quadrants. Displacements along the x- and y-axes can be measured using measurements of light from diametrically opposite positions. Measurements along the z-axis can be made using the radial distribution of signals around the beam.

[0063] The method includes a fifth step 5 of determining whether the determined position measured in the third step 3 is a desired position.

[0064] If the signals received at the detector from the reflected light are approximately evenly distributed across the locations, the determined location along the x and y axes will be the desired location. The radial distribution of the measurement signals received at all the locations may determine the z-axis location. If the determined location is at the desired location, the method proceeds to a sixth step 6, which provides a signal indicating that the ophthalmic instrument is aligned with the eye, for example by directing a flash of visible light at the eye or emitting an audible sound.

[0065] If the signals received at the detector from the reflected light are not evenly distributed across the positions, the determined position will not be the desired position. The method will proceed to a seventh step 7 of moving the ophthalmic instrument from the determined position relative to the eye to the desired position. Movement of the instrument relative to the eye is performed to equalize any imbalance in the measurements received at the detector.

[0066] The method includes repeating steps 2 to 5 to determine whether the ophthalmic instrument is aligned with the eye in a desired position. It will be appreciated that steps 2 to 5 are repeated until the desired position is achieved. The detectors may be positioned at asymmetric angles about the z-axis and at non-uniform distances along the z-axis, which may need to be taken into account when determining the position of the ophthalmic device relative to the eye.

[0067] An exemplary apparatus will now be described with reference to FIG. 2. The apparatus 100 is for aligning an ophthalmic instrument 20 with respect to a patient's eye 40. The ophthalmic instrument 20 is a pneumatic aesthesiometer having a nozzle 22. The sensitivity of the surface of the eye is determined by measuring the patient's response to air being blown onto the eye 40 through the nozzle 22. The illumination unit 10 is located at one end of the aesthesiometer 20 through which the air is delivered. The nozzle 22 is an elongated tube having a receiving hole 22' and an exit hole 22". The nozzle 22 has a diameter of 1 mm. In other embodiments, the nozzle 22 may have a diameter in the range of 0.1 mm to 6 mm.

[0068] The illumination unit 10 includes two different light sources: an infrared light source 4 and a visible light source 2. The illumination unit 10 also has a beam splitter 3. In this embodiment, the beam splitter 3 is configured to allow the infrared light 4 to pass with minimal reflection or deflection. The visible light source 2 is arranged perpendicular to the infrared light source 4 and is arranged to be reflected at the surface of the beam splitter 3. Both the infrared light source 4 and the visible light source 2 are directed in the same direction towards the exit opening of the illumination unit 10. The exit opening of the illumination unit 10 is arranged at the entrance hole 22' of the nozzle 22, which directs the infrared light 4 and the visible light 2 to the eye 40. In this example, the illumination unit 10 is attached to the nozzle 22 such that both the illumination unit 10 and the nozzle 22 move together.

[0069] The cornea of ​​the eye protrudes outward and is generally convex. The cornea transmits visible light so that signals can be sent to the brain and converted into an image. The visible light source 2 provides the patient with information regarding the alignment of the patient's eye relative to the ophthalmic instrument 20.

[0070] The infrared light source 4 is a low intensity light source. The infrared light 8 is reflected from the cornea of ​​the eye 40 because the cornea is opaque to infrared light. The curved surface of the cornea will reflect the infrared light 8 away from the eye at an angle to the direction of the incident light. The angle of reflection will depend on the position of the aesthesiometer 20 relative to the surface of the eye along the x-, y-, and z-axes.

[0071] The reflected infrared radiation 18 is detected by a number of detectors 28 arranged around the nozzle. The detectors are integrated on a plate 30, such as a sensor printed circuit board (PCB). The plate 30 has a central hole 31 for the nozzle 22 to pass through. The plate 30 has a circular shape. In other embodiments, the plate may have a different shape. Figure 2 shows four infrared detectors 28, two of which are arranged above the nozzle 22 and two below the nozzle 22. Further detectors (not shown) are provided on either side of the nozzle 22 in the horizontal plane. In other embodiments, the outermost detector 26 may be a visible light detector.

[0072] Four detectors 28 may be positioned around the nozzle 22 at 90° angles to each other, preferably symmetrically positioned around the nozzle at positions above and below the nozzle 22 and to the right and left of the nozzle 22. This is shown in FIG. 5a and described in more detail below. In another exemplary embodiment, there are additional detectors positioned to the left and right of the nozzle 22, respectively, as shown in FIG. 5b and described in more detail below. The detectors 28 are positioned to measure the intensity of the reflected light 18 to determine the position of the aesthesiometer 20 relative to the eye 40 along the x-axis and y-axis, and to measure the radial distribution of the reflected light 18 to determine the position of the aesthesiometer 20 relative to the eye 40 along the z-axis. In other embodiments, the detectors 28, 26 may be positioned differently around the nozzle 22.

[0073] The plate 30 and the detectors 26, 28 are positioned at a distance away from the exit hole 22'' of the nozzle 22. The distance between the detectors 26, 28 and the exit hole 22'' of the nozzle 22 is 5 mm. (The distance between the detectors 26, 28 and the exit hole 22'' of the nozzle 22 can be from 0.5 mm to 200 mm.)

[0074] A microcontroller 52 is connected to the plate 30. It may be wired or wirelessly connected (e.g., using Wi-Fi or Bluetooth). The microcontroller 52 receives information from the detectors 26, 28. The microcontroller 52 may control the position of the plate 30 along the length of the nozzle 22. In this embodiment, the plate 30 is fixed relative to the nozzle 22. In other embodiments, the plate 30 may move along the z-axis. The plate may be rotatable about the axis of the nozzle 22.

[0075] The control unit 50 receives the detection signals from the detectors 26, 28 via the microcontroller 52. The control unit 50 converts the detected signals into two components (intensity and position of the reflected light 18 at each detector 26, 28) and determines the position of the nozzle 22 relative to the eye 40 by comparing the signals at each detector 26, 28. If the determined position is not the desired position, i.e. not aligned with the center of the cornea of ​​the eye 40, the control unit 50 instructs the light source driver 54 to move the illumination unit 10 and, therefore, the aesthesiometer 20 in a direction along the x-axis, the y-axis and / or the z-axis. If the aesthesiometer 20 is at the desired position, the illumination unit 10 and the aesthesiometer 20 will remain stationary. The control unit 50 can also instruct the light source driver 54 to change the intensity of the light sources 4, 2.

[0076] An exemplary embodiment 200 of a device for aligning an ophthalmic instrument with respect to a patient's eye 140 is shown in a partial perspective view in FIG. 3. FIG. 3 shows the device 200 being used on the patient's eye 140. The device 200 is substantially identical to the device previously described in FIG. 2, and like features are given the same reference numbers, but with the addition of the digit "1" at the beginning. The device 200 of this embodiment comprises a housing 180 that houses an illumination unit 110 having an infrared light source 104, a visible light source 102, and a beam splitter 103, and a control unit (not shown) for moving the components of the device 200. The housing 180 has an opening configured to receive and connect with a keratometer having a nozzle 122. The nozzle 122 is partially inside the housing 180 and partially outside the housing 180. An exit opening of the illumination unit 110 is connected to the nozzle 122 to direct light from the illumination unit 110 to the patient's eye 140.

[0077] On the outside of the housing 180, near the location of the housing opening, there is a plate 130 with multiple detectors 128. The plate 130 has a central hole for the nozzle 122 and is attached to the outside of the housing 180 at multiple fixed positions by a fastening means. In this embodiment, the plate 130 is attached to the outside of the housing 180 via screws at four fixed positions. In other embodiments, the plate may be attached to the outside of the housing 180 at more than four fixed positions or may be attached by other fastening means such as adhesive. In this embodiment, as shown in FIG. 5b, the plate 130 has six detectors 128 arranged symmetrically around the nozzle 122.

[0078] Outside the opening of the housing 180, the housing 180 is connected to the eye attachment 170. The eye attachment 170 has two parts: a connecting portion 174 configured to be screwed or slid onto the housing 180, and a curved eye portion 172 shaped to complement the patient's eye socket. The connecting portion 174 is circular and configured to receive and fit around the outer portion of the nozzle 122, the plate 130, and the detector 128. The eye portion 172 has a smaller diameter than the connecting portion 174. The distal end of the eye portion 172 is shaped to complement the shape of the patient's eye socket, which aids in the alignment process by reducing movement of the device 200 and provides better comfort to the patient. Additionally, the eye attachment 170 prevents stray light from the external environment from entering the patient's eye 140 and the possibility of the patient looking away.

[0079] FIG. 4a shows a cross-section of a beam of light entering the ophthalmic instrument 220 and directed towards the eye 240, with a ray trace showing the direction of reflected light 218 from the cornea 242 of the eye 240. Some features of this embodiment are the same as those previously described with reference to FIG. 2, and like features are given the same reference numbers but with the addition of the numeral "2" at the beginning. An infrared beam 208 is directed from a light source (not shown) to an entrance aperture 222' of a nozzle 222 of the ophthalmic instrument 220. The entrance aperture 222' has an opening diameter 223 that is larger than the diameter of the exit aperture 222". The exit aperture 222" of the nozzle 222 collimates the light 208 and defines the spot size of the light 208. In this example, the beam diameter 225 is 1 mm. It will be understood that other nozzles 222 may have different sized exit apertures 222'', for example the size may be between 0.5 and 1.5 mm. When the light beam 208 exits the nozzle 222 it is directed towards the cornea 242 of the eye 240 and is reflected at an angle θ relative to the incident light beam. Due to the curvature of the cornea the reflected light 218 is directed away from the nozzle 222 towards a detector 228. The detectors 228 are positioned at a fixed distance from the exit aperture 222'' along the z axis and are symmetrically arranged around the nozzle 222. In this embodiment only two detectors 228 above and below the nozzle 222 can be seen. Further detectors (not shown) may be provided on either side of the nozzle 222 in the horizontal plane.

[0080] FIG. 4b shows an example of the beam diameter size 225' relative to the diameter of the eye's pupil 227. In this example, the beam diameter 225' is 1 mm and the pupil diameter is 6 mm, giving a position uncertainty of ±2.5 mm. However, it has been shown (confirmed) that for a beam spot size of 1 mm, a signal is detectable at the detector 228, subject to an accuracy of ±0.4 mm in the z-axis and an accuracy of ±0.1 mm in the x- and y-axes. Reference numeral 229 shows the pupil size relative to the beam diameter of the light (visible light) used in the alignment system, and the error of the xy positioning when the alignment system is not used. This error may occur if the subject only sees the light for the xy alignment (without a sensor measuring the light reflected from the cornea).

[0081] 5a and 5b show exemplary detector arrangements as viewed along the direction of the incident beams 308,408.

[0082] 5a shows a detector arrangement 300 having four detectors arranged symmetrically around the beam 308. There are two identical y-axis detectors 328 arranged symmetrically above and below the beam 308, and there are two identical x-axis detectors 338 arranged symmetrically to the left and right of the beam 308.

[0083] FIG. 5b shows detector arrangement 400 with a total of six detectors symmetrically arranged around beam 408. There are two identical y-axis detectors 428 symmetrically arranged above and below beam 408. There are four identical x-axis detectors 438 symmetrically arranged parallel to the x-axis. Two detectors adjacent to each other along the y-axis are on the left side of beam 308 and two more detectors adjacent to each other along the y-axis are on the right side of beam 308. Although not clearly visible from the schematic, the two y-axis detectors 428 lie on a ring having a first radius centered on beam 408, forming an inner ring of detectors. The four x-axis detectors 438 also lie on a ring having a second (larger) radius centered on beam 408, forming an outer ring of detectors.

[0084] 6a and 6b show measurement data that provides information regarding the alignment of an ophthalmic device relative to the eye.

[0085] FIG. 6a shows a plot of the signal detected by the detector described in FIG. 5b from light reflected from the cornea. Each red dot corresponds to a pulse of the received signal. The central cluster 60 of red dots at (0,0) corresponds to the nominal position of the eye, i.e., where the ophthalmic instrument is aligned relative to the eye. The top cluster 64 of red dots at coordinates (0,900) indicates a shift in the reflected light of +0.5 mm along the y-axis. The left cluster 62 of red dots at coordinates (-1100,-200) indicates a shift in the reflected light of +0.5 mm along the x-axis. The off-axis clusters 62, 64 of red dots can be used to identify the position of the ophthalmic instrument relative to the cornea of ​​the eye. The ophthalmic instrument can then be moved relative to the eye (or the eye can be moved relative to the ophthalmic instrument) until the red dots are approximately centered 60. Although referred to as "red dots" in the figure, these dots are shown as black dots in the drawings.

[0086] Measurements are obtained by detector arrangements 400' or 400", as shown on the right side of the plot in Figure 6a. The position of the ophthalmic instrument relative to the eye can be determined by signals received at a set of diametrically opposed detectors 64a and 64b, 62a and 62b. In one detector arrangement 400', signals received at the upper half 64a of the detector arrangement are compared to signals received at the lower half 64b of the detector arrangement to provide a y-axis component of the position of the ophthalmic instrument relative to the eye. In another detector arrangement 400", signals received at detector arrangement 62a to the left of the light beam 68 are compared to signals received at detector arrangement 62b to the right of the light beam 68 to provide an x-axis component of the position of the ophthalmic instrument relative to the eye.

[0087] FIG. 6b shows a plot of the radial distribution of the inner and outer radial signals received by detectors located on the inner and outer rings, respectively. These signals provide information about the alignment of the ophthalmic instrument with respect to the eye along the z-axis. The nominal position 70 of the ophthalmic instrument with respect to the eye along the z-axis is approximately at coordinate position (100,10), which corresponds to a distance of 5 mm between the nozzle outlet opening and the surface of the cornea of ​​the eye. The top cluster of red dots 72, approximately at coordinate position (475,78), indicates a reflected light deviation of +1.0 mm along the z-axis. The left cluster of red dots 74, approximately at coordinate position (0,0), indicates a reflected light deviation of -1.0 mm along the z-axis. The off-axis clusters of red dots 72, 74 can be used to identify the distance between the ophthalmic instrument and the cornea of ​​the eye. If the measured position is not the desired position, the Ophthalmic instrument may be moved relative to the eye (or the eye may be moved relative to the Ophthalmic instrument) until the red dot is approximately centered 70 .

[0088] Measurements are taken by detector arrangements 400"', 400"", as shown on the right side of the plot in FIG. 6b. The position of the ophthalmic instrument relative to the eye along the z-axis can be determined by measuring the absolute intensity at diametrically opposed detectors 74a, 74b in the inner ring of detectors or by measuring the absolute intensity at diametrically opposed detectors 72a, 72b in the outer ring of detectors. Absolute intensity measurements from diametrically opposed detectors 72a, 72b in the outer ring of detectors and absolute intensity measurements from diametrically opposed detectors 74a, 74b in the inner ring of detectors can be used to determine the position of the ophthalmic instrument relative to the eye along the z-axis over the entire dynamic range.

[0089] Alternatively, the position of the ophthalmic device relative to the eye along the z-axis may be determined from relative intensity measurements: Intensity may be measured at diametrically opposed detectors 74a, 74b in an inner ring of detectors and compared to the intensity measured at dynamically opposite detectors 72a, 72b in an outer ring of detectors.

[0090] FIG. 7 is a schematic cross-sectional view of an exemplary embodiment of a device 500 for aligning an ophthalmic instrument 520 with respect to an eye 540. Some of the features of this embodiment are the same as those described above with reference to FIG. 2. These features are given the same reference numbers, but with the addition of the number "5" at the beginning. Different features of this embodiment will now be described. The device 500 comprises a housing 570 that contains an illumination unit 510 having an infrared light source 504, an ophthalmic instrument 520 having a nozzle 522 that directs infrared light 508 towards the cornea of ​​the patient's eye 540, and a detector arranged around the nozzle 522. The device 500 also comprises a camera 560 positioned at a 90° angle with respect to the optical axis of the eye 540. The camera 560 is positioned to the side of the eye such that the viewing axis of the camera is arranged to observe the surface of the eye, i.e. the cornea. The camera 560 is arranged to assist in the alignment of the ophthalmic instrument 520 with respect to the cornea of ​​the eye 540. Reflected light 518 from eye 540 is shown. Camera 560 provides additional assistance to the instructor by presenting a visual image of the position of the eye relative to the ophthalmic instrument 520. Camera 560 is attached to a separate mount or support bracket 572 that is connected to a housing 570. Camera 560 is connected to a control unit 550 for exchanging information and controlling the position of the camera relative to eye 540.

[0091] Although the present invention has been described and illustrated with reference to specific embodiments, those skilled in the art will appreciate that the invention is also susceptible to many different variations not specifically set forth herein. By way of example only, some possible variations are now described.

[0092] In the exemplary embodiment shown in FIG. 2, there may be a second detector set arranged circumferentially around the first detector set. For example, the first detector set may have four detectors arranged at 90° angles to each other around the central hole 31 of the plate 30. The second detector set may have four detectors arranged at 90° angular positions and arranged circumferentially around the first detector set. The additional detector positioned furthest from the central hole 31 may provide information about the radial distribution of the reflected light 18, which determines the position of the aesthesiometer 20 relative to the eye 40 along the z-axis. There may be more infrared detectors 28 distributed around the central hole 31, for example, there may be eight detectors in total, each detector arranged at a 45° angle to each other around the central hole 31.

[0093] In some embodiments, the control unit 50 may include a user interface (not shown). As the control unit 50 determines the position of the nozzle 22 relative to the eye 40, the user interface may display visual information, such as a graph or chart showing the position of the reflected light 18 around the nozzle 22. The examiner may use this information to manually move the aesthesiometer 20 relative to the eye 40. The examiner may use the information to instruct the patient to move their head relative to the aesthesiometer 20.

[0094] In an exemplary embodiment of the device 100, the visible light source 2 is used as an indicator of the alignment of the nozzle 22 with respect to the patient's eye. The control unit 50 may instruct the visible light source 2 to transmit pulses of visible light 6 to the eye 40, for example, transmitting a beam of red light if the determined position is not at the desired position. If the determined position is at the desired position, the visible light source 2 may transmit a beam of green light. In other examples, other colors may be used. The visible light 6 may be a pattern of multiple pulses.

[0095] In the exemplary embodiment shown in FIG. 7, the camera 560 may be positioned along the x-axis or y-axis at any position around the optical axis. The camera 560 may capture multiple images of the cornea of ​​the eye 540. The camera 560 may be a video recorder that records the alignment of the ophthalmic instrument 520 with respect to the eye 540. The control unit 550 may store data acquired from the camera 560, which may be saved, displayed, or printed as an image. The control unit 550 may cause the image to be displayed on a user interface so that the examiner can see a real-time view of the lateral side of the eye 540. The control unit 550 may also be configured to adjust the position of the camera 560. There may be one or more actuators (not shown) that move the camera 560 relative to the eye 540. In other embodiments, the position of the camera 560 may be adjusted manually, for example by the examiner. The camera 560 may not be connected to the control unit 550. The support bracket 572 may be a tripod that is separate from the housing 570 of the device 500 .

[0096] Where the foregoing description refers to integers or elements having known, obvious, or foreseeable equivalents, such equivalents (equivalents) are incorporated herein as if set forth separately. To determine the true scope of the invention, reference should be made to the claims, which should be interpreted to embrace all such equivalents. The reader will also understand that integers or features of the invention described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. It should further be understood that such optional integers or features may be beneficial in some embodiments of the invention, but may be undesirable in other embodiments and therefore may not be present.

[0097] The present invention includes the following aspects / embodiments / features in any order and / or in any combination.

[0098] 1) A method of aligning an ophthalmic instrument with respect to an eye, comprising: a) directing a beam of light from the ophthalmic device towards the eye; b) obtaining measurements of the reflection of the light from the eye at a plurality of positions around the beam; c) determining a position of the ophthalmic device relative to the eye from the measurements; and d) moving the ophthalmic instrument relative to the eye from the determined position to a desired position; A method comprising:

[0099] 2) aligning the ophthalmic device with respect to a center of the cornea of ​​the eye, the ophthalmic device being aligned a predetermined distance away from the cornea. The method according to claim 1), further comprising:

[0100] 3) The beam of light is collimated. The method according to claim 1) or 2),

[0101] 4) The intensity of the reflected light is measured. 3) A method according to any one of claims 1) to 3).

[0102] 5) The reflected light is reflected from the cornea. 5. The method according to any one of claims 1) to 4).

[0103] 6) The reflected light is measured at at least three positions. 5) A method according to any one of claims 1) to 5).

[0104] 7) The plurality of locations are symmetrically arranged around the beam. 5. The method according to claim 1, wherein the first and second electrodes are arranged in a first direction.

[0105] 8) The determining step provides a position of the ophthalmic instrument relative to the eye in one, two, and / or three spatial axes. 8. The method according to any one of claims 1 to 7.

[0106] 9) The determining step includes calculating a difference in the light received at each of the plurality of locations. 10. The method according to any one of claims 1 to 8.

[0107] 10) The determining step includes calculating a total amount of incident light received at each of the plurality of locations. 10) A method according to any one of claims 1) to 9) above,

[0108] 11) The moving step is in a direction that equalizes the measurements of reflected light at corresponding locations around the beam. 10) A method according to any one of claims 1 to 10,

[0109] 12) providing instructions for moving the ophthalmic instrument relative to the eye. The method according to any one of items 1) to 11), further comprising:

[0110] 13) An apparatus for aligning an ophthalmic instrument with respect to an eye, comprising: a collimated light source configured to be directed through an aperture to the eye; a plurality of detectors disposed about the aperture to measure light reflected from the eye; a control unit configured to determine a position of the ophthalmic instrument relative to the eye and to move the relative position of the ophthalmic instrument and the eye from the determined position to a desired position; An apparatus comprising:

[0111] 14) The light is infrared. 14) The device according to claim 13).

[0112] 15) The light is directed through an elongated nozzle. 14) The device according to claim 13) or 14).

[0113] 16) The detectors are arranged symmetrically around the aperture. 15) A device according to any one of claims 13) to 15).

[0114] 17) The detector is a photodiode. 17) A device according to any one of claims 13) to 16).

[0115] 18) An actuator for adjusting the distance of the ophthalmic instrument relative to the eye. The device according to any one of items 13) to 17), further comprising:

[0116] 19) An apparatus according to any one of items 13) to 18). An ophthalmic instrument comprising:

[0117] 20) The ophthalmic instrument is a keratometer. 19) The device according to claim 19.

[0118] 21) The light is directed from the nozzle of the keratometer. 20) The device according to claim 20.

[0119] The present invention may include any combination of the various features or embodiments described above and / or below (as described in the claims), as described in sentences and / or paragraphs. Any combination of features disclosed herein is considered to be part of the present invention. No limitations are intended with respect to features that may be combined.

[0120] The applicant specifically incorporates the entire contents of all cited documents herein. Furthermore, when an amount, concentration, or other value or parameter is given as a range, a preferred range, or a list of a preferred upper value and a preferred lower value, this should be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is disclosed individually. When a numerical range is described herein, unless otherwise specified, the range is intended to include both endpoints and all integers and fractions within the range. It is not intended that the scope of the present invention be limited to the specific values ​​described in defining a range.

[0121] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary. A true scope and spirit of the invention is indicated by the following claims and their equivalents.

[0122] As used herein, an element or operation described in the singular following "a" or "an" should be understood not to exclude a plurality of elements or operations, unless such exclusion is expressly stated. In other words, "a" or "an" includes one, or at least one, or more than one. Furthermore, references to "one embodiment," "one embodiment," or a "preferred embodiment" in this disclosure are not intended to exclude additional embodiments that incorporate the described features.

[0123] Although specific embodiments have been illustrated and described herein, it should be understood that any arrangements calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of the various embodiments. It should be understood that the foregoing description is intended to be illustrative and not restrictive. Combinations of the foregoing embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the foregoing description. Thus, the scope of the various embodiments includes any other applications in which the compositions, structures, and methods described above are used. Accordingly, the claims set forth below should be construed in light of the full scope and spirit of the invention as described herein.

Claims

1. 1. A method of aligning an ophthalmic device with respect to a center of a cornea of ​​an eye, comprising: a) directing a beam of light from the ophthalmic device toward the cornea of ​​the eye along an optical axis of the eye; b) obtaining measurements of the intensity of the light reflected from the cornea of ​​the eye using at least three photodiodes at multiple locations around the beam; c) determining a position of the ophthalmic device relative to the eye from the measurements of the intensity of the light reflected from the cornea of ​​the eye in three spatial axes; d) moving the ophthalmic device relative to the eye from the determined position to a desired position within the three spatial axes; Equipped with The desired position is a position that equalizes measurements of the intensity of the light reflected from the cornea of ​​the eye using the at least three photodiodes at multiple positions around the beam. A method characterized by:

2. aligning the ophthalmic device with respect to the center of the cornea of ​​the eye, the ophthalmic device being positioned a predetermined distance away from the cornea; 10. The method of claim 1, further comprising:

3. The beam of light is collimated 2. The method of claim 1 .

4. The photodiodes are arranged symmetrically around the beam.

2. The method of claim 1 .

5. The determining step includes calculating a difference in the intensity of the light received at each of the plurality of locations.

2. The method of claim 1 .

6. The determining step includes calculating a total amount of incident light received at each of the plurality of locations.

2. The method of claim 1 .

7. providing instructions for moving the ophthalmic instrument relative to the eye; 10. The method of claim 1, further comprising:

8. 1. An apparatus for aligning an ophthalmic instrument with respect to a center of a cornea of ​​an eye, comprising: Opening and a collimated light source positioned along an optical axis of the eye and configured to be directed through the aperture toward the cornea of ​​the eye; at least three photodiodes arranged around the aperture to measure the intensity of light reflected from the cornea of ​​the eye; a control unit configured to determine a position of the ophthalmic device relative to the eye in three spatial axes and to provide instructions to a user interface and / or actuator for adjusting a distance of the ophthalmic device relative to the cornea of ​​the eye from the determined position to a desired position; Equipped with The desired position is a position that equalizes measurements of the intensity of the light reflected from the cornea of ​​the eye using the at least three photodiodes at multiple positions around the beam. An apparatus characterized in that

9. The light is infrared light.

9. The device according to claim 8.

10. The light is directed through an elongated nozzle 9. The device according to claim 8.

11. The photodiodes are arranged symmetrically around the aperture.

9. The device according to claim 8.

12. 9. The apparatus of claim 8 An ophthalmic device comprising:

13. The ophthalmic instrument is a keratometry instrument.

13. The ophthalmic device of claim 12.

14. The light is directed from the nozzle of the aesthesiometer.

14. The ophthalmic device of claim 13.

Images