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 a method and apparatus for aligning an ophthalmic instrument with an eye. More specifically, but not exclusively, the present disclosure relates to aligning a corneal esthesiometer with a patient's eye.

Background Art

[0002] Many ophthalmic instruments must be accurately aligned with the eye. For example, an ophthalmic instrument such as a corneal esthesiometer is used to measure the corneal sensitivity of the surface of the eye. Conventionally, corneal sensitivity has been measured using a contact method, but this method can provide inaccurate measurements. An example of such an instrument is one that uses a single nylon thread to exert various forces on the cornea. Another example of a less invasive method for measuring corneal sensitivity is non-contact air puff technology (pneumatic esthesiometer). In this technique, the pressure or flow rate of the air puff blown onto the cornea can be changed until the patient senses it.

[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 orbit can vary from patient to patient. This can make it difficult to align an instrument with the cornea. If the eye moves during the alignment process, misalignment of the ophthalmic instrument with the eye can occur.

[0004] In conventional pneumatic sensory metering systems, the nozzle position is adjusted by the examiner using a two-camera system. One camera observes the distance from the cornea to the nozzle (z-direction), and the other positions the nozzle at the center of the cornea (x, y-directions). Positioning the cameras can be time-consuming, especially when multiple instruments need to be set up. The patient is required to remain still and keep at least one eye open, which can be uncomfortable for the patient. Furthermore, if the positioning is not the same from visit to visit, it can be a potential source of variability. Integrating two camera systems to detect eye position is demanding both spatially and computationally, which can increase the complexity of the detection system and limit the minimum system size. [Overview of the Initiative]

[0005] The purpose of this disclosure is to provide an improved method and apparatus for aligning ophthalmic instruments with respect to the eye.

[0006] According to a first aspect of this disclosure, a method having the features described in claim 1 is provided.

[0007] According to a second aspect of this disclosure, an apparatus having the features described in claim 13 is provided.

[0008] According to a third aspect of this disclosure, an ophthalmic instrument having the features described in claim 19 is provided.

[0009] Preferred but optional (non-essential) features of this disclosure are described below in the description and dependent claims.

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

[0011] Embodiments of the present disclosure are described only illustratively with reference to the attached schematic diagrams. [Brief explanation of the drawing]

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

[0013] [Figure 2] Figure 2 schematically shows a device for aligning an ophthalmic instrument with respect to the eye, according to the second embodiment.

[0014] [Figure 3] Figure 3 shows a partial perspective view of a device for aligning ophthalmic instruments with respect to the eye, according to the third embodiment.

[0015] [Figure 4a] Figures 4a and 4b show a cross-sectional view of a beam of light directed towards an eye and reflected from the eye, according to the fourth embodiment. [Figure 4b] Figures 4a and 4b show a cross-sectional view of a light beam directed towards an eye and reflected from the eye, according to the fourth embodiment.

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

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

[0018] [Figure 6a] Figure 6a shows graph data representing signals received by a detector according to the sixth embodiment for aligning ophthalmic equipment along the x and y axes.

[0019] [Figure 6b]FIG. 6b shows graph data representing signals received by a detector according to a sixth embodiment for aligning an ophthalmic device along the z-axis.

[0020] [Figure 7] FIG. 7 schematically shows an apparatus for aligning an ophthalmic instrument according to a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] In a first aspect, the present disclosure provides a method for aligning an ophthalmic device with respect to an eye. The method includes directing a beam of light from the ophthalmic device 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 device with respect to the eye from the measurements, and moving the ophthalmic device with respect to the eye from the determined position to a desired position.

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

[0023] The ophthalmic device can be a corneal esthesiometer (esthesiometer). The ophthalmic device can be positioned in front of the eye along the direction of the optical axis of the eye. Ophthalmic examinations, particularly those related to corneal sensitivity, require a high level of accuracy. The present method can shorten the time required to align the device with respect to the eye, provide continuous monitoring of the position of the eye, and increase the accuracy of alignment. By shortening the time required to align an ophthalmic device with respect to an eye, an examiner (such as an optometrist or an ophthalmologist) can spend more time evaluating the patient.

[0024] This method may include a step of aligning an ophthalmic instrument with the center of the cornea. The size and structure of the cornea may vary from patient to patient. This method provides an improved method for aligning an ophthalmic instrument with the center of the cornea and positioning it at a predetermined distance from the cornea.

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

[0026] The beam of light (ray) may be a collimated beam. 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] This method may include a step of measuring the intensity of light reflected from the eye at multiple locations around the beam. The intensity of light reflected from the eye is used to determine the position of an ophthalmic instrument relative to the eye. The reflected light may be reflected from the cornea of ​​the eye. As mentioned above, if the area of ​​interest is the cornea of ​​the eye, the light beam may be sized to be limited to the corneal region, so that the light is reflected only from the cornea.

[0028] The measurement of reflected light can determine the position of ophthalmic instruments in three dimensions, namely, along the z-axis, defined as the direction of the optical axis of the eye, and along the x and y axes, which define planes perpendicular to the optical axis of the eye. The x and y-axis positions of the ophthalmic instrument relative to the eye can be determined independently of the z-axis position of the ophthalmic instrument relative to the eye.

[0029] Light can be reflected directly from the eye. Light incident on the surface of the eye can be reflected back along the direction of the incident light beam. In a perfect configuration where the cornea of ​​the eye is perfectly convex and the instrument is precisely positioned at the center of the cornea, if the beam of light is extremely narrow and incident on a minimum point on the cornea, the light will be reflected back along the direction of the beam. In reality, even when perfectly aligned, the incident light beam has a finite diameter and the angle of incidence to the cornea also has a range, so the light is reflected from the convex surface at a range of angles with respect to the axis of the incident light beam.

[0030] Reflected light can be measured, for example, at three, four, five, six, seven, eight, or more than eight positions around the beam of light. These positions can be distributed circumferentially around the beam of light. For example, if there are four positions around the beam of light where light is measured, they could be above, below, to the left, and to the right of the beam.

[0031] Reflected light can be measured at positions symmetrically arranged around the beam of light. For example, reflected light can be measured at positions above and below the beam of light, and / or to the left and right of the beam of light, with each position positioned at a 90-degree angle to the others. Preferably, when the instrument is precisely positioned relative to the eye, the measured values ​​of the reflected light are distributed symmetrically across multiple positions. This is advantageous because it can provide a guide for positioning the instrument relative to the eye when there is some imbalance in the distribution of light at symmetrical positions around the beam of light.

[0032] The process of determining the position of an ophthalmic instrument relative to the eye can 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 and y axes can be determined by comparing the light intensity at two positions opposite each other in the diametrical direction. For example, the position of the ophthalmic instrument along the x axis relative to the eye can be determined by calculating the difference in light intensity measured at positions 180° apart on both sides of the light beam, e.g., to the left and to the right of the light beam. The position of the ophthalmic instrument along the y axis relative to the eye can be determined by calculating the difference in light intensity measured above and below the light beam.

[0033] The process of determining the position of an ophthalmic instrument relative to the eye may include a step of calculating the total amount of incident light received at multiple positions. The total amount of light incident at multiple positions may provide positional information of the ophthalmic instrument along the z-axis relative to the eye.

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

[0035] The method may include a step of providing instructions for moving an ophthalmic instrument relative to the eye. A control actuator may exist that is configured to receive instructions and move the instrument relative to the eye. The method may include a step of instructing the patient to move their head / eye relative to the ophthalmic instrument. A display or other visible light source may exist that can provide instructions to the patient in the form of signals. The method may include a step of giving instructions to an examiner. A user interface may exist that is configured to receive instructions and display them 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 / eye relative to the ophthalmic instrument. For example, they may explain the instructions verbally.

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

[0037] In a second embodiment, the Disclosure provides a device for aligning an ophthalmic instrument with respect to an eye. The device comprises a collimating light source configured to be directed towards the eye through an aperture; a plurality of detectors arranged around the aperture to measure light reflected from the eye; and a control unit configured to determine the position of the ophthalmic instrument with respect to the eye and to move the relative position of the ophthalmic instrument with respect to 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. However, to obtain corneal measurements using visible light, depending on the situation, high-intensity visible light may be required for the light to reflect from the cornea, which can be dangerous to other parts of the eye. The use of infrared light offers greater safety as an alternative to using high-intensity visible light, and can also improve the amount of light reflected from the eye, thus providing a rapid measurement of the position of ophthalmic instruments relative to the eye.

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

[0040] The device may have multiple light sources. Each light source may emit light of a different frequency; for example, infrared LEDs and visible light LEDs may be present. Other light sources known to those skilled in the art may also be used. Visible light sources may be combined with infrared light sources to improve the alignment of ophthalmic instruments with respect to the eye. In a healthy eye, the cornea is transparent to visible light. Low-intensity visible light sources may signal the patient to center their eye relative to the ophthalmic instrument. Visible light may have various colors to provide the patient with guidance for positioning the eye. For example, red, yellow, and green light may be present to indicate whether the eye is too close, too far, or in the correct position relative to the ophthalmic instrument. Light may provide special information by changing its color, or by changing its amplitude or special patterns (e.g., flashing light). Light may be a simple point to the user and can be used as a fixed target. This could be an LED light source, in which case the light can be incident on the retina through a lens or a series of lenses (a simple LED without a lens may be visible as an unfocused point on the retina). In other embodiments, a mask may be imaged onto the retina through a lens or a 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 a series of lenses to focus the display onto the retina. Alternatively, there may be other signal sources, such as audible sounds, to help the patient orient their eyes to the ophthalmic instrument.

[0041] The aperture through which light is guided may be a long, slender tube. The aperture may be connected to or fixed to a light source. The aperture may have an incident portion into which light enters and an outgoing portion into which light exits. The aperture is positioned such that the outgoing portion is close to the surface of the eye. The outgoing portion 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, it may be the nozzle of a pneumatic sensory device into which air is directed.

[0042] Light can be collimated (parallelized) by a light source. There may be optical components that collimate (parallelize) the light. The nozzle of a pneumatic sensory meter may be configured to direct and collimate (parallelize) the light.

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

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

[0045] The device may comprise at least three detectors, for example, which may be arranged around the aperture at angles of 120° from each other. The device may comprise more than three detectors. The device may comprise three to ten detectors positioned around the aperture.

[0046] Detectors can be arranged symmetrically around the aperture. Symmetrically positioned detectors provide a better measurement of the distribution of light reflected from the eye. Measurement of reflected light can be used to determine the position of the ophthalmic instrument relative to the eye in three dimensions, i.e., along the z-axis and / or along the x and y axes. The position of the ophthalmic instrument along the x and y axes relative to the eye can 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 can provide the y-axis position of the ophthalmic instrument relative to the eye. The position of the ophthalmic instrument along the z-axis relative to the eye can be determined by measuring the change in the radiative distribution of reflected light in the detectors. In some embodiments, increasing the number of detectors dispersed circumferentially and radially around the aperture can provide more accurate measurements 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. Different detectors may exist to detect light of different frequencies. 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 around the first set of detectors.

[0048] The detector may be positioned away from the aperture's exit point along the optical axis. The detector may be positioned a certain distance from the eye for optimal detection and distribution of light. The detector may be mounted on a plate. The plate may be circular and have a central hole so that incident light is directed from the light source towards the eye. The central hole of the plate may be configured to fit around the 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 a detector to receive detected signals. The control unit may determine (determine) the position of the ophthalmic instrument relative to the eye.

[0050] The apparatus described herein may include a computing system which is part of a control unit 50 (exemplary) for controlling the detector and other functions described herein. The computing system may include, for example, a general-purpose processor, a digital signal processor (DSP) for sequentially processing 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 memory for storing 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 for enabling 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 touchscreen 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, or a combination thereof.

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

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

[0053] A control unit may be connected to an actuator. The actuator may be configured to move a detector and / or plate. The control unit may be connected to multiple actuators, one of which may be connected to an ophthalmic instrument. The control unit may instruct the actuator to move the ophthalmic instrument from a 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 a light source. The control unit may control the intensity, beam size, or frequency of the light. For example, if the detected signal is weak, the control unit may increase the intensity of the infrared light. If the detected position is a desired position, the control unit may instruct a visible light source to transmit a beam of light of a specific color (e.g., green) to signal that the desired position has been achieved.

[0055] The apparatus may perform method steps according to a first aspect of this 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 ophthalmic instruments to the eye. The camera may be connected to a control unit. The control unit may have a user interface for displaying images. The camera may capture multiple images to provide real-time information on the eye's position. These images may be displayed or printed to assist in the process of aligning ophthalmic instruments to the eye.

[0057] According to a third aspect, an ophthalmic instrument is disclosed that includes the apparatus described in a second aspect, which may be a corneal sensory meter. The corneal sensory meter may have an elongated nozzle for air passage. The nozzle may be configured to guide light from a light source into the eye.

[0058] Other exemplary embodiments are described in further detail with reference to Figures 1 to 7.

[0059] Figure 1 illustrates the process of aligning an ophthalmic instrument with the eye. There is a first step 1, in which the ophthalmic instrument is initially aligned with the eye, preferably with respect to the center of the cornea. The cornea must be visible to the examiner when the patient's eye is open. This alignment may be performed by the examiner, or it may be performed by an actuator directed by a control unit.

[0060] A second step 2 involves directing a beam of light from an ophthalmic instrument towards the eye. The beam of light is nearly collimated (parallelized) and preferably infrared (IR).

[0061] A third step 3 is present in which light reflected from the cornea of ​​the eye at multiple positions around the beam is measured. The incident light beam may be a substantially circular light beam with a corresponding diameter. The curvature of the cornea of ​​the eye can be approximated as a convex surface that reflects light away from the direction of the incident light beam. In some embodiments, it is preferable to have at least three positions around the light beam. At each position, there is a detector, such as a photodiode, or any other detector capable of detecting IR light. The detector is capable of measuring the intensity of the reflected light at each position.

[0062] This method includes a fourth step 4 in which the position of an ophthalmic instrument relative to the eye is determined by comparing the distribution of reflected light across multiple positions. The position of an ophthalmic instrument relative to the eye can be determined by comparing the signals received at each position around a beam of light. Preferably, the detectors can be arranged symmetrically around the beam at equidistant points along the z-axis, for example, four detectors can be positioned around the beam at angles of 90° to each other, so that the (four) detectors form (four) quadrants. Displacements along the x and y axes can be measured using measurements of light from each position that is diametrically opposite to each other. Measurements along the z-axis can be performed using the distribution of the radiation direction of the signal around the beam.

[0063] This method includes a fifth step 5 in which a determination is made as to whether the position measured in the third step 3 is the desired position.

[0064] If the signals received by the detector from the reflected light are distributed almost evenly across multiple locations, the determined positions along the x and y axes will be the desired positions. The distribution of the radiation directions of the measurement signals received at all positions can determine (determine) the position along the z axis. If the determined position is the desired position, the method proceeds to 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 by the detector from the reflected light are not evenly distributed across multiple positions, the determined position will not be the desired position. The method will proceed to step 7, in which the ophthalmic instrument is moved from the determined position to the desired position relative to the eye. The movement of the instrument relative to the eye is performed in such a way that the imbalance in the measurements received by the detector is equalized.

[0066] This method includes repeating steps 2 through 5 to determine whether the ophthalmic instrument is positioned on the eye in the desired location. It will be understood that steps 2 through 5 are repeated until the desired position is achieved. The detector may be positioned at an asymmetric angle around the z-axis and at a non-uniform distance along the z-axis, and these may need to be taken into consideration when determining the position of the ophthalmic instrument relative to the eye.

[0067] Next, an exemplary apparatus will be described with reference to Figure 2. Apparatus 100 is a device for aligning an ophthalmic instrument 20 with a patient's eye 40. The ophthalmic instrument 20 is a pneumatic corneal sensory meter having a nozzle 22. The sensitivity of the eye surface is determined by measuring the patient's response to air blown onto the eye 40 through the nozzle 22. An illumination unit 10 is located at one end of the corneal sensory meter 20, from which the air is supplied. 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 lighting unit 10 includes two different light sources, namely an infrared light source 4 and a visible light source 2. The lighting 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 through with minimal reflection or deflection. The visible light source 2 is positioned perpendicular to the infrared light source 4 and is positioned to be reflected off 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 toward the exit opening of the lighting unit 10. The exit opening of the lighting unit 10 is located in the inlet hole 22' of the nozzle 22, which directs the infrared light 4 and visible light 2 toward the eye 40. In this example, the lighting unit 10 is mounted on the nozzle 22 such that both the lighting unit 10 and the nozzle 22 move together.

[0069] The cornea of ​​the eye protrudes outward and is almost convex. Because the cornea transmits visible light, signals can be sent to the brain and converted into images. The visible light source 2 provides the patient with information regarding the alignment of the patient's eyes with respect to the ophthalmic instrument 20.

[0070] The infrared light source 4 is a low-intensity light source. Since the cornea does not transmit infrared light, the infrared light 8 is reflected from the cornea of ​​the eye 40. The curvature of the cornea will cause the infrared light 8 to be reflected obliquely to the direction of the incident light, so as to move away from the eye. The angle of reflection will depend on the position of the corneal sensory meter 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 plurality of detectors 28 arranged around the nozzle. The detectors are integrated onto a plate 30, such as a sensor printed circuit board (PCB). The plate 30 has a central hole 31 through which the nozzle 22 passes. The plate 30 is circular in shape. In other embodiments, the plate may have a different shape. Figure 2 shows four infrared detectors 28, two of which are positioned above the nozzle 22 and the remaining two are positioned below the nozzle 22. Further detectors (not shown) are provided on both sides 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 arranged around the nozzle 22 at 90° angles to each other, preferably symmetrically 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 Figure 5a and will be described in more detail below. In another exemplary embodiment, there are additional detectors arranged to the left and right of the nozzle 22, respectively, as shown in Figure 5b and will be described in more detail below. The detectors 28 are arranged to measure the intensity of reflected light 18 to determine the position of the corneal sensor 20 relative to the eye 40 along the x and y axes, and to measure the distribution of the radiation direction of the reflected light 18 to determine the position of the corneal sensor 20 relative to the eye 40 along the z axis. In other embodiments, the detectors 28, 26 may be arranged differently around the nozzle 22.

[0073] The plate 30 and the detectors 26 and 28 are positioned at a certain distance from the exit hole 22" of the nozzle 22. The distance between the detectors 26 and 28 and the exit hole 22" of the nozzle 22 is 5 mm. (The distance between the detectors 26 and 28 and the exit hole 22" of the nozzle 22 may range from 0.5 mm to 200 mm.)

[0074] A microcontroller 52 is connected to the plate 30. It may be connected by wire or wirelessly (e.g., using Wi-Fi or Bluetooth). The microcontroller 52 receives information from detectors 26 and 28. The microcontroller 52 can 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 also be rotatable about the axis of the nozzle 22.

[0075] The control unit 50 receives detection signals from detectors 26 and 28 via the microcontroller 52. The control unit 50 converts the detected signals into two components (intensity and position of reflected light 18 at each detector 26 and 28) and determines (determines) the position of the nozzle 22 relative to the eye 40 by comparing the signals at each detector 26 and 28. If the determined (determined) position is not the desired position, i.e., it is 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, thereby moving the corneal sensor 20 in the direction along the x, y, and / or z axes. If the corneal sensor 20 is in the desired position, the illumination unit 10 and the corneal sensor 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 and 2.

[0076] Figure 3 shows a partial perspective view of an exemplary embodiment 200 of a device for aligning an ophthalmic instrument to a patient's eye 140. Figure 3 shows the device 200 used on a patient's eye 140. The device 200 is substantially identical to the device described in Figure 2, with the same reference numerals for the same features, but with the addition of the digit "1" at the beginning. The device 200 of this embodiment comprises a housing 180 housing 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 to a corneal sensory device 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, directing light from the illumination unit 110 to the patient's eye 140.

[0077] A plate 130 having multiple detectors 128 is located near the housing opening on the outside of the housing 180. 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 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 it may be attached by other fastening means such as adhesive. In this embodiment, as shown in Figure 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 screw or slide onto the housing 180, and a curved eye portion 172 shaped to complement the patient's orbit. The connecting portion 174 is circular and configured to accommodate 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 farthest end of the eye portion 172 is shaped to complement the shape of the patient's orbit, assisting the alignment process by reducing the movement of the device 200 and providing better comfort to the patient. Furthermore, the eye attachment 170 prevents stray light from the external environment from entering the patient's eye 140, preventing the patient from averting their gaze.

[0079] Figure 4a shows a cross-section of a beam of light incident on an ophthalmic instrument 220 and directed toward the eye 240, with ray tracing indicating the direction of reflected light 218 from the cornea 242 of the eye 240. Some features of this embodiment are identical to those described above with reference to Figure 2, and the same features are denoted by the same reference numerals, but with the number "2" added to the beginning. An infrared beam 208 is directed from a light source (not shown) to the inlet opening 222' of the nozzle 222 of the ophthalmic instrument 220. The inlet opening 222' has an aperture diameter 223 that is larger than the diameter of the exit opening 222''. The exit opening 222'' of the nozzle 222 collimates (parallels) the light 208 and defines the spot size of the light 208. In this embodiment, the beam diameter 225 is 1 mm. Other nozzles 222 may have exit holes 222” of different sizes, for example, the size of which may be 0.5 to 1.5 mm. When the light beam 208 exits the nozzle 222, it is directed toward the cornea 242 of the eye 240 and reflected at an angle θ with respect to the incident light beam. Due to the curvature of the cornea, the reflected light 218 is directed away from the nozzle 222 toward the detector 228. The detector 22 is positioned at a certain distance from the exit opening 222” along the z-axis and is symmetrically arranged around the nozzle 222. In this embodiment, only the two detectors 228 above and below the nozzle 222 are visible. Further detectors (not shown) may be provided on both sides of the nozzle 222 in the horizontal plane.

[0080] Figure 4b shows one embodiment of a beam diameter size 225' relative to the diameter of the pupil 227 of the eye. In this embodiment, the beam diameter 225' is 1 mm and the pupil diameter is 6 mm, giving a positional uncertainty of ±2.5 mm. However, it was shown (confirmed) that a signal for a 1 mm beam spot size is detectable by the detector 228 under the conditions of 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 indicates the pupil size relative to the beam diameter of the light (visible light) used in the alignment system, and the error in xy position determination when the alignment system is not used. That is, if the subject only looks at the light for xy alignment (without a sensor to measure reflected light from the cornea), this error can occur.

[0081] Figures 5a and 5b show exemplary detector configurations as viewed along the directions of the incident beams 308 and 408.

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

[0083] Figure 5b shows a detector arrangement 400 having 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 located on the left side of beam 308, and two more detectors adjacent to each other along the y-axis are located on the right side of beam 308. Although not clearly visible in this schematic diagram, the two y-axis detectors 428 are on a ring with a first radius centered on beam 408, forming an inner ring of detectors. The four x-axis detectors 438 are also on a ring with a second radius (larger radius) centered on beam 408, forming an outer ring of detectors.

[0084] Figures 6a and 6b show measurement data that provides information regarding the positioning of ophthalmic instruments relative to the eye.

[0085] Figure 6a shows a plot of signals detected by the detector described in Figure 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 with the eye. The upper cluster 64 of red dots at coordinates (0,900) indicates a shift of +0.5 mm in reflected light along the y-axis. The left cluster 62 of red dots at coordinates (-1100,-200) indicates a shift of +0.5 mm in reflected light along the x-axis. Clusters 62 and 64 of red dots off-axis can be used to identify the position of the ophthalmic instrument relative to the cornea of ​​the eye. The ophthalmic instrument may then be moved relative to the eye (or the eye may be moved relative to the ophthalmic instrument) until the red dot is approximately centered at 60. Although referred to as "red dots" in the figure, these dots are shown as black dots in the drawing.

[0086] The measurements are obtained by detector configuration 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 the signals received by a set of diametrically opposed detectors 64a and 64b, 62a and 62b. In one detector configuration 400', the signal received by the upper half 64a of the detector configuration is compared with the signal received by the lower half 64b of the detector configuration to provide the y-axis component of the position of the ophthalmic instrument relative to the eye. In another detector configuration 400'', the signal received by detector configuration 62a to the left of the light beam 68 is compared with the signal received by detector configuration 62b to the right of the light beam 68 to provide the x-axis component of the position of the ophthalmic instrument relative to the eye.

[0087] Figure 6b shows a plot of the radial distribution of the inner and outer radius signals received by detectors positioned in the inner and outer rings, respectively. These signals provide information regarding the alignment of the ophthalmic instrument relative to the eye along the z-axis. The nominal position 70 of the ophthalmic instrument relative 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 exit opening and the surface of the cornea of ​​the eye. The upper cluster of red dots 72 at approximately coordinate position (475,78) indicates a reflected light shift of +1.0 mm along the z-axis. The left cluster of red dots 74 at approximately coordinate position (0,0) indicates a reflected light shift of -1.0 mm along the z-axis. The clusters of red dots 72 and 74 off-axis 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 at the center 70.

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

[0089] Alternatively, the position of the ophthalmic instrument relative to the eye along the z-axis can be determined from relative intensity measurements. The intensity can be measured by diametrically opposed detectors 74a and 74b located in the inner ring of the detector, and this can be compared with the intensity measured by dynamically opposite detectors 72a and 72b located in the outer ring of the detector.

[0090] Figure 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 identical to those described above with reference to Figure 2. These features are given the same reference numerals, but with the number "5" added to the beginning. Different features of this embodiment are now described. The device 500 comprises a housing 570 housing an illumination unit 510 having an infrared light source 504, an ophthalmic instrument 520 having a nozzle 522 for directing infrared 508 toward the cornea of ​​a patient's eye 540, and a detector positioned 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 laterally to the eye such that the camera's field of view axis is positioned to observe the surface of the eye, i.e., the cornea. The camera 560 is positioned to assist in aligning 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 visible image of the eye's position relative to the ophthalmic instrument 520. Camera 560 is mounted on a separate mount or support bracket 572 connected to the housing 570. Camera 560 is connected to a control unit 550 to exchange information and control the camera's position 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 understand that the invention is also suitable for many different modifications not specifically shown herein. Hereinafter, several possible modifications are described for illustrative purposes only.

[0092] In the exemplary embodiment shown in Figure 2, there may be a second set of detectors arranged circumferentially around the first set of detectors. For example, the first set of detectors may have four detectors arranged at 90° angles to each other around the central hole 31 of the plate 30. The second set of detectors may have four detectors arranged at 90° angles and circumferentially around the first set of detectors. An additional detector positioned furthest from the central hole 31 may provide information regarding the directional distribution of reflected light 18, which determines (determines) the position of the corneal sensory meter 20 relative to the eye 40 along the z-axis. Further infrared detectors 28 may be dispersed around the central hole 31, for example, there may be a total of eight detectors, each detector arranged at 45° angles to each other around the central hole 31.

[0093] In some embodiments, the control unit 50 may have a user interface (not shown). When 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 graphs or charts, showing the position of the reflected light 18 around the nozzle 22. The examiner may use this information to manually move the corneal sensory meter 20 relative to the eye 40. The examiner may use this information to instruct the patient to move their head relative to the corneal sensory meter 20.

[0094] In an exemplary embodiment of the device 100, a visible light source 2 is used as a guide for aligning the nozzle 22 with 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, if the determined position is not the desired position, it may transmit a beam of red light. If the determined position is the desired position, the visible light source 2 may transmit a beam of green light. In other embodiments, other colors may be used. The visible light 6 may be a pattern of multiple pulses.

[0095] In the exemplary embodiment shown in Figure 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 acquire (take) 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 the data acquired from the camera 560, which may be saved as an image, displayed, or printed. The control unit 550 may display the image on a user interface so that an examiner can view a real-time lateral view 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 an examiner. The camera 560 may not be connected to the control unit 550. The support bracket 572 may be a tripod independent of the housing 570 of the device 500.

[0096] Where, in the foregoing description, integers or elements having known, obvious, or foreseeable equivalents are referred to, such equivalents are incorporated herein as if they were described separately. To determine the true scope of the invention, the claims should be referred to, and the claims should be interpreted to encompass all such equivalents. It will also be understood by the reader 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. Furthermore, it should be understood that such optional integers or features may be beneficial in some embodiments of the invention but undesirable and therefore absent in other embodiments.

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

[0098] 1) A method for aligning an ophthalmic instrument with respect to the eye, a) A step of directing a beam of light from the ophthalmic instrument toward the eye, b) A step of obtaining measurements of the reflection of the light from the eye at multiple locations around the beam, c) A step of determining the position of the ophthalmic instrument relative to the eye based on the measured values, d) A step of moving the ophthalmic instrument relative to the eye from the determined position to a desired position, A method characterized by comprising:

[0099] 2) A step of aligning the ophthalmic instrument with respect to the center of the cornea of ​​the eye, wherein the instrument is positioned at a predetermined distance from the cornea. The method according to claim 1), further comprising the following:

[0100] 3) The beam of light is collimated light. The method according to item 1) or 2), characterized by the features described herein.

[0101] 4) The intensity of the reflected light is measured. The method according to any one of items 1) to 3), characterized by the features described herein.

[0102] 5) The reflected light is reflected from the cornea. The method according to any one of items 1) to 4), characterized by the above.

[0103] 6) The reflected light is measured at at least three locations. The method according to any one of items 1) to 5), characterized by the features described herein.

[0104] 7) The plurality of positions are arranged symmetrically around the beam. The method according to any one of items 1) to 6), characterized by the above.

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

[0106] 9) The determination step includes the step of calculating the difference in the light received at each of the plurality of locations. The method according to any one of items 1) to 8), characterized by the features described above.

[0107] 10) The determination step includes the step of calculating the total amount of incident light received at each of the plurality of positions. The method according to any one of items 1) to 9), characterized by the above.

[0108] 11) The moving step is performed in a direction that equalizes the measured values ​​of the reflected light at corresponding positions around the beam. The method according to any one of items 1) to 10), characterized by the features described herein.

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

[0110] 13) A device for aligning ophthalmic instruments with respect to the eye, A collimated light source configured to be directed towards the eye through an aperture, A plurality of detectors arranged around the aperture to measure the light reflected from the eye, A control unit configured to determine the position of the ophthalmic instrument relative to the eye, and to move the relative position between the ophthalmic instrument and the eye from the determined position to a desired position, An apparatus characterized by being equipped with

[0111] 14) The light is infrared. The apparatus according to item 13), characterized in that

[0112] 15) The light is directed through an elongated nozzle. The apparatus according to item 13) or 14), characterized in that it is a device.

[0113] 16) The detectors are arranged symmetrically around the aperture. The apparatus according to any one of items 13) to 15), characterized in that it is a device.

[0114] 17) The detector is a photodiode. The apparatus according to any one of items 13) to 16), characterized in that it is a device.

[0115] 18) Actuator for adjusting the distance of the ophthalmic instrument to the eye. The apparatus according to any one of items 13) to 17), further comprising the above.

[0116] Apparatus as described in any of paragraphs 19) 13) through 18) An ophthalmic instrument characterized by having the following features.

[0117] 20) The ophthalmic instrument is a corneal sensory meter. The apparatus according to item 19), characterized in that

[0118] 21) The light is directed from the nozzle of the corneal sensory meter. The apparatus according to item 20), characterized in that

[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 the text and / or paragraphs. Any combination of the features disclosed herein is considered part of the present invention. No limitation is intended with respect to the combinatable features.

[0120] The applicant incorporates the entire contents of all cited documents into this specification. Furthermore, where quantities, concentrations, or other values ​​or parameters are given as ranges, preferred ranges, or lists of preferred upper and lower limits, this should be understood to specifically disclose all ranges formed by any pair of any upper range limits or preferred values ​​and any lower range limits or preferred values, regardless of whether the ranges are disclosed individually or not. Where a numerical range is described in this specification, unless otherwise specified, the range is intended to include its endpoints and all integers and fractions within that range. The scope of the present invention is not intended to be limited to the specific values ​​described when defining a range.

[0121] Other embodiments of the present invention will be apparent to those skilled in the art from the discussion herein and the practice of the present invention disclosed herein. This specification and the examples are intended to be considered illustrative. The true scope and spirit of the present invention are shown by the claims and their equivalents.

[0122] Where used herein, an element or operation described in the singular form followed by "a" or "an" should be understood not to exclude multiple elements or operations unless such exclusion is explicitly stated. In other words, "a" or "an" includes one, at least one, or more than one. Furthermore, references in this disclosure to "one embodiment," "one embodiment," or "preferred embodiment" are not intended to exclude additional embodiments incorporating the described features.

[0123] While specific embodiments are illustrated and described herein, it should be understood that any arrangement calculated (intended) to achieve the same objective may be substituted for the specific embodiments shown. This disclosure is intended to cover all possible adaptations or variations of the various embodiments. It should be understood that the foregoing description is illustrative and not restrictive. Combinations of the foregoing embodiments, and other embodiments not specifically described herein, will be apparent to those skilled in the art when considering the foregoing description. Accordingly, the scope of the various embodiments includes any other applications in which the foregoing compositions, structures, and methods are used. Accordingly, the claims set forth below should be interpreted in light of the entire scope and spirit of the invention as described herein. The claims at the time of filing are as follows: [Claim 1] A method for aligning ophthalmic instruments with respect to the eye, a) A step of directing a beam of light from the ophthalmic instrument toward the eye, b) A step of obtaining measurements of the reflection of the light from the eye at multiple locations around the beam, c) A step of determining the position of the ophthalmic instrument relative to the eye based on the measured values, d) A step of moving the ophthalmic instrument relative to the eye from the determined position to a desired position, A method characterized by comprising: [Claim 2] A step of aligning the ophthalmic instrument with the center of the cornea of ​​the eye, wherein the instrument is positioned at a predetermined distance from the cornea. The method according to claim 1, further comprising the following: [Claim 3] The aforementioned beam of light is collimated light. The method according to feature 1. [Claim 4] The intensity of the reflected light is measured. The method according to feature 1. [Claim 5] The reflected light is reflected from the cornea. The method according to feature 1. [Claim 6] The reflected light is measured at at least three locations. The method according to feature 1. [Claim 7] The aforementioned plurality of positions are arranged symmetrically around the beam. The method according to feature 1. [Claim 8] The aforementioned determination step provides the position of the ophthalmic instrument relative to the eye in one, two, and / or three spatial axes. The method according to feature 1. [Claim 9] The determination step includes the step of calculating the difference in the light received at each of the plurality of locations. The method according to feature 1. [Claim 10] The aforementioned determination step includes a step of calculating the total amount of incident light received at each of the plurality of positions. The method according to feature 1. [Claim 11] The moving step is performed in a direction that equalizes the measured values ​​of the reflected light at corresponding positions around the beam. The method according to feature 1. [Claim 12] A step of providing instructions for moving the ophthalmic instrument relative to the eye. The method according to claim 1, further comprising the following: [Claim 13] A device for aligning ophthalmic instruments with the eye, A collimated light source configured to be directed towards the eye through an aperture, A plurality of detectors arranged around the aperture to measure the light reflected from the eye, A control unit configured to determine the position of the ophthalmic instrument relative to the eye, and to move the relative position between the ophthalmic instrument and the eye from the determined position to a desired position, An apparatus characterized by being equipped with [Claim 14] The aforementioned light is infrared light. The apparatus according to feature 13. [Claim 15] The aforementioned light is directed through a long, narrow nozzle. The apparatus according to feature 13. [Claim 16] The detectors are arranged symmetrically around the aperture. The apparatus according to feature 13. [Claim 17] The detector is a photodiode. The apparatus according to feature 13. [Claim 18] Actuator for adjusting the distance of the ophthalmic instrument to the eye. The apparatus according to claim 13, further comprising the following: [Claim 19] The apparatus according to any one of claims 13 to 18 An ophthalmic instrument characterized by having the following features. [Claim 20] The aforementioned ophthalmic instrument is a corneal sensory meter. The ophthalmic instrument according to feature 19. [Claim 21] The light is directed from the nozzle of the corneal sensory meter. The ophthalmic instrument according to feature 20.

Claims

1. A method for aligning an ophthalmic instrument with the center of the cornea of ​​the eye, a) A step of directing a beam of light from the ophthalmic instrument toward the cornea of ​​the eye along the direction of the optical axis of the eye, b) A step of obtaining a measurement of the intensity of the light reflected from the cornea of ​​the eye using at least three photodiodes at multiple positions around the beam, c) A step of determining the position of the ophthalmic instrument relative to the eye from the measured values ​​of the intensity of the light reflected from the cornea of ​​the eye in three spatial axes, d) A step of moving the ophthalmic instrument 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 where, at least three photodiodes are used to equalize the measured intensity of the light reflected from the cornea of ​​the eye at multiple positions around the beam. A method characterized by the following:

2. A step of aligning the ophthalmic instrument with respect to the center of the cornea of ​​the eye, wherein the instrument is positioned at a predetermined distance from the cornea. The method according to claim 1, further comprising the following:

3. The aforementioned beam of light is collimated light. The method according to feature 1.

4. The photodiodes are arranged symmetrically around the beam. The method according to feature 1.

5. The determination step includes the step of calculating the difference in the intensity of the light received at each of the plurality of locations. The method according to feature 1.

6. The aforementioned determination step includes a step of calculating the total amount of incident light received at each of the plurality of positions. The method according to feature 1.

7. A step of providing instructions for moving the ophthalmic instrument relative to the eye. The method according to claim 1, further comprising the following:

8. A device for aligning ophthalmic instruments with the center of the cornea of ​​the eye, Opening and, A collimated light source configured to be directed towards the cornea of ​​the eye through the aperture and positioned along the optical axis of the eye, At least three photodiodes arranged around the aperture and measuring the intensity of light reflected from the cornea of ​​the eye, A control unit configured to determine the position of the ophthalmic instrument relative to the eye in three spatial axes, and to provide instructions to a user interface and / or actuator for adjusting the distance of the ophthalmic instrument from the determined position to the cornea of ​​the eye to a desired position, Equipped with, The desired position is a position where, at least three photodiodes are used to equalize the measured intensity of the light reflected from the cornea of ​​the eye at multiple positions around the collimated light from the collimated light source. A device characterized by the following features.

9. The aforementioned light is infrared light. The apparatus according to feature 8.

10. The aforementioned light is directed through a long, narrow nozzle. The apparatus according to feature 8.

11. The photodiodes are arranged symmetrically around the aperture. The apparatus according to feature 8.

12. The apparatus according to claim 8 An ophthalmic instrument characterized by having the following features.

13. The aforementioned ophthalmic instrument is a corneal sensory meter. The ophthalmic instrument according to feature 12.

14. The light is directed from the nozzle of the corneal sensory meter. The ophthalmic instrument according to feature 13.

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