Apparatus and Methods for Determining Refraction of an Eye

Abstract

Apparatus, methods, and a computer program for determining a refraction of an eye are disclosed. An apparatus for determining an objective refraction of an eye is disclosed where the apparatus includes an optical element configured to compensate an aberration of the eye.

Claims

1. An apparatus for determining an objective refraction of an eye, comprising: an optical element configured to compensate an aberration of the eye.

2. The apparatus according to claim 1, wherein the optical element is configured to compensate a third or higher order aberration of the eye.

3. The apparatus according to claim 1, wherein the optical element is configured to compensate a first order aberration and/or a second order aberration of the eye.

4. The apparatus according to claim 1, wherein the optical element is configured to compensate an aberration of a cornea of the eye.

5. The apparatus according to claim 4, wherein the optical element is configured to compensate the aberration of the cornea based at least in part on topographic and/or tomographic information of the cornea.

6. The apparatus according to claim 1, wherein the optical element comprises an adaptive optics and/or an adaptive mirror.

7. The apparatus according to claim 1, further comprising: a detector for detecting an electromagnetic wave reflected by the eye; and a divider element positioned between the detector and the eye, wherein the divider element is configured to divide the electromagnetic wave into a plurality of wave components.

8. The apparatus according to claim 7, wherein the divider element is configured such that at least one of the wave components comprises a portion of the electromagnetic wave originating from a corresponding region on a surface of a cornea of the eye, and wherein the optical element is configured to compensate the aberration in order to: reduce an amount of the electromagnetic wave in the at least one of the wave components that originates from a different region of the cornea; and/or increase the portion of the electromagnetic wave originating from the corresponding region of the cornea comprised by the at least one of the wave components.

9. The apparatus according to claim 8, wherein the optical element is configured to compensate the aberration such that the at least one of the wave components has a one-to-one correspondence to the corresponding region of the cornea.

10. The apparatus according to claim 1, wherein the apparatus further comprises an optical path for determining a subjective refraction associated with the eye, wherein the optical element is arranged in the optical path.

11. The apparatus according to claim 1, wherein the apparatus further comprises an iris diaphragm diameter controlling component configured to control a diameter of an iris diaphragm of the eye by illuminating the iris of the eye.

12. A method for determining an objective refraction of an eye, comprising: compensating an aberration of the eye by an optical element.

13. The method according to claim 12, further comprising: obtaining and/or measuring topographic and/or tomographic information of a cornea of the eye; wherein the compensating comprises compensating an aberration of the cornea based on the topographic and/or tomographic information.

14. The method according to claim 13, wherein the compensating further comprises compensating a first order, a second order, a third order, and/or a higher order aberration of the eye.

15. A non-transitory computer-readable medium having instructions stored thereon that are executable by a computing device to perform operations, comprising: compensating an aberration of an eye by an optical element to determine an objective refraction of the eye.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 shows a block diagram of an exemplary apparatus according to some embodiments.

[0056] FIG. 2 is a schematic representation of an Objective Refraction Channel (ORC) of an exemplary apparatus according to some embodiments, to determine an objective refraction of a patient's eye.

[0057] FIG. 3 shows a schematic representation of an electromagnetic wave reflected at a retina of an eye and exiting a cornea of the eye.

[0058] FIG. 4 shows a magnified view of a portion of FIG. 3.

[0059] FIG. 5 is a schematic representation of a Dynamic Pupillometric Channel (DPC) of an exemplary apparatus, to analyze and control the iris diaphragm diameter.

[0060] FIG. 6 is a schematic representation of a Subjective Refraction Channel (SRC) of an exemplary apparatus, to analyze the patient's subjective refraction.

[0061] FIG. 7 is a schematic representation of an exemplary apparatus comprising ORC, SRC, and DPC channels.

[0062] FIG. 8 is a schematic representation of the iris diaphragm diameter of the eye (E).

DETAILED DESCRIPTION

[0063] In FIG. 1, a schematic representation of an eye E is depicted with respect to a block diagram of an exemplary apparatus D according to some embodiments. The exemplary apparatus D may enable determining a refraction of an eye of an individual (e.g., a patient) and may be configured to implement various types of measurements. The exemplary apparatus may include an optical divider DV that may serve to connect (or switch) various optical paths of the exemplary apparatus with each other (or onto each). The optical divider may include one or more partially reflecting mirrors and/or a lozenge optical divider. For example, there may be a main optical path between the optical divider DV and the eye. The optical divider may be configured such that the optical divider DV connects a first optical path i1, a second optical path i2 and/or a third optical path i3 with the main optical path u. The optical divider may thus divide the main optical path u into separate optical paths (e.g., the first optical path i1, the second optical path i2, the third optical path i3, etc.). The herein described optical paths may be bidirectional such that an electromagnetic wave (e.g., light) may travel in both directions of the optical paths. For example, light may be guided onto the eye via one or more optical paths and light may also be guided from the eye onto the divider element to the various other optical paths (e.g., i1, i2 and/or i3) of the exemplary apparatus D.

[0064] In some examples, optical divider DV may be omitted and only path i2 or only path i3 may be present.

[0065] The optional first optical path i1 may be connected to an optional apparatus unit that is configured to control the diameter of the iris diaphragm wherein said apparatus unit (as well as the optical path of said apparatus unit) may be referred to as the dynamic pupillometric channel DPC (or DPC unit). The second optical path i2 may be connected to an apparatus unit that is configured to determine the objective refraction of the eye wherein said apparatus unit (as well as the optical path of said apparatus unit) may be referred to as the objective refraction channel ORC (or ORC unit). The third optical path i3 may be connected to an apparatus unit that is configured to determine the subjective refraction of the eye wherein said apparatus unit (as well as the optical path of said apparatus unit) may be referred to as the subjective refraction channel SRC (or SRC unit).

[0066] Notably, in FIG. 1, the objective refraction channel ORC and the subjective refraction channel SRC are arranged on different and separate optical paths only for an easier comprehension of the disclosed embodiments. However, elements of the optometric measurement channels SRC and/or ORC can also rest on the dynamic pupillometric channel DPC (or DPC unit) and vice-versa. The herein described different measurement channels (or apparatus units) may also share parts of a same optical path.

[0067] In an example, the exemplary apparatus includes all three of the herein described units, namely the DPC unit, the ORC unit and the SRC unit. However, as stated herein, the apparatus according to the disclosed embodiments may include any combination of the three units and may not be limited to a certain number of units. For example, the apparatus D may solely include the ORC unit (and may thus solely be used to determine an objective refraction). In another example, the apparatus D may solely include the SRC unit (and may thus solely be used to determine a subjective refraction). In a further example, the apparatus may include the ORC unit and the SRC unit such that an objective, as well as a subjective refraction can be determined via the apparatus D. In addition, the apparatus may also include the DPC unit in combination with the ORC unit and/or the SRC unit such that the determination of the objective and/or subjective refraction may be accompanied by the functionality of the DPC unit. To that regard, the DPC unit may enable to measure and control the diameter of the iris diaphragm while an optometry measurement is executed via the ORC unit and/or SRC unit.

[0068] Notably, the DPC unit, the ORC unit and/or the SRC unit may be separate apparatuses and may thus be coupled by the optical divider DV to form a system that functions as if it were a single apparatus according to the disclosed embodiments. Alternatively, they may form an integrated system.

[0069] In the following, the units of the apparatus and their possible interactions and combination are explained.

[0070] FIG. 2 shows a schematic representation of an exemplary Objective Refraction Channel ORC (or an ORC unit) of an exemplary apparatus according to some embodiments, to determine an objective refraction of an individual's eye. The objective refractometric measurement of the eye E may be executed in far distance vision condition and/or in accommodated near distance vision condition which may be achieved by means of the apparatus described further herein. To determine an objective refraction, initially a light beam may be guided into the eye E such that it is reflected by the retina of the eye and may subsequently pass through the eye's lens and the cornea of the eye. The part of the light beam that is guided into the eye may be referred as the optical input to the eye's optical system wherein the part of the light beam that is reflected at the retina may be referred to as the optical output of the eye's optical system. The reflected light beam (i.e., the optical output) exiting the cornea may be subsequently measured to determine the eye's objective refraction. FIG. 2 shows to that regard schematically the eye E and the objective refraction path i2 that the light beam (also referred to herein as the objective refraction OR light beam) reflected at the retina is guided onto.

[0071] As the exemplary apparatus may include various other optical components for analyzing the eye, the OR light beam may initially pass various optical components (such as an LED assembly 3 and/or an optical divider DV) that may not significantly interfere with the OR light beam. Subsequently the OR light beam may pass a focusing lens 18 which may include various lenses to focus and/or collimate the OR light beam. Subsequently, the OR light beam may be shaped by an optical element as described herein to compensate a (specific) aberration of the eye. The optical element may include various components to shape the OR light beam (however, the herein described optical element may also be included of a single optical component). In the example of FIG. 2, the optical element may include a group of tilting mirrors 21 that may include a first tilting mirror 21a and a second tilting mirror 21b. The optical element may further include an optical correction group 9. The optical correction group 9 may include a first correction unit 9a, a second correction unit 9b and a third correction unit 9c. The components of the optical element may, according to some embodiments, correct the light of the OR light beam such that the (specific) aberration of the eye is not substantially present anymore and thus compensated. The OR light beam exiting the optical element may thus be a corrected OR light beam (having the (specific) aberration suppressed). The corrected OR light beam may be subsequently guided through various other optical components (e.g., an optical divider 11, a bandpass filter 15) and eventually may enter a wavefront analyzer 16. The wavefront analyzer 16 may include a divider element, e.g. a multi-lens optics, e.g., in the form of a lenslet array 25, and the herein described detector for detecting the (corrected) OR light beam. The wavefront analyzer may also include a pyramidal optic (as the divider element) and the herein described detector to implement a pyramidal wavefront sensor, for example. The compensation by the optical element may ensure that the OR light beam impinging onto the wavefront analyzer 16 (e.g., onto its multi-lens optics, its lenslet array, its pyramidal optic and/or its detector) is a corrected OR light beam that does not include a (specific) aberration of the eye. For example, this may ensure that a noise of the (specific) aberration that may alter the measurement is reduced. In another example, the compensation by the optical element may also enable determining a (specific) aberration of the eye.

[0072] In the following, aspects of the exemplary optical element and its components are described.

[0073] The tilting mirrors 21a and 21b of the tilting mirrors group 21 may be used to correct components Kx and Ky of an angle K of the OR light beam exiting the eye E. The mirrors 21a and 21b may be preferably motorized and controlled by a control unit 13 of the apparatus which may enable a dynamical compensation of the components Kx and Ky of the angle K. For example, the tilting mirrors 21a and 21b may compensate the first order aberration of the eye which may be a vertical tilt and/or a horizontal tilt (e.g., according to the first order Zernike polynomials).

[0074] The optical correction group 9 may be motorized and include a series of lenses and/or mirrors to compensate a second order aberration (e.g., a second order spherical and/or cylindrical refractive aberration), as well as a high order aberration of the eye for the OR light beam. The optical correction group 9 may be controlled by the control unit 13 to dynamically compensate the objective refraction of the eye E measured by the wavefront analyzer 16.

[0075] The optical unit 9a may enable to compensate or correct a second order spherical aberration (e.g., a spherical refractive error, e.g., a defocus). This may be achieved with a motorized spherical optic controlled by the control unit 13. For example, the optical unit 9a may include a lens that can be shifted along the optical path of the OR light beam to correct a second order spherical aberration of the eye E that was imparted onto the OR light beam. In a further example, the compensation by the optical unit 9a may be achieved by a spherical optic with an adaptive profile controlled by the control unit 13.

[0076] The optical unit 9b may enable to compensate or correct a second order cylindrical aberration of the eye E that was imparted onto the OR light beam (e.g., a cylindrical refractive error, e.g., regular astigmatism). This may be achieved with a motorized cylindrical optic that compensates optical power and angle stemming from the second order cylindrical aberration by means of the control unit 13 (the optical unit may thus compensate a cylindrical diopter value with a certain cylinder axis value). In a further example, this may be achieved by a cylindrical optic having an adaptive profile that compensates optical power and angle stemming from the second order cylindrical aberration by means of the control unit 13. Notably, the optical unit 9b may include any correction mechanism known in the field for correcting a second order cylindrical aberration of the eye.

[0077] The optical unit 9c may enable to compensate or correct higher order aberration of the eye. The higher order aberration may include a third order or even higher order aberration of the eye (or the cornea) as described herein. The optical unit 9c may include an adaptive optic/mirror 9c which can be used to compensate one or more higher order aberrations of the eye E. This may be achieved by the adaptive optic/mirror 9c which may be shaped, by means of a set of piezoelectric actuators that may be controlled by control unit 13 such that one or more higher order aberrations of the eye E that were imparted onto the OR light beam are compensated. The adaptive optic/mirror 9c may include a deformable mirror that can be adjusted via the set of piezoelectric actuators.

[0078] In an example, the adaptive optic/mirror 9c may be shaped to compensate the higher order corneal refractive aberrations of the cornea E which were detected by means of a corneal topographer and/or tomographer 19. The corneal refractive aberrations usually represent the highest percentage of the total higher order aberrations of the eye and may thus impart the most effect onto the OR light beam.

[0079] In another example, the control unit 13 may control the shape of the adaptive optic/mirror 9c to also compensate the first order aberration of the eye E and/or the spherical second order aberration of the eye E and/or the cylindrical second order aberration of the eye E. The adaptive/mirror optic 9c may thus partially or completely replace the respective functionality of the tilting mirrors 21a and 21b and/or the optical unit 9a and/or the optical unit 9b.

[0080] In an example of the present disclosure, the control unit 13 may receive the (higher order) corneal refractive aberration of the eye E measured by means of a corneal topographer or tomographer 19 and may preventively control the shape of the adaptive optic/mirror 9c to compensate the (higher order) corneal refractive aberration of the eye E. The measured wavefront data may thus be corrected from the effect of the (higher order) corneal refractive aberrations of the eye. Subsequently, the control unit 13 may detect the compensated wavefront data measured by the wavefront analyzer 16. Based on the measured wavefront data, the aberrations of the eye without the effect of the corneal refractive aberration may be determined. However, based on the measured wavefront data, the control unit 13 may further iteratively control the other beam shaping optics in the apparatus to compensate the remaining aberrations of the eye present in the OR light beam (e.g. via the optical element and its components). For example, the control unit 13 may further control the mirrors 21a and 21b to compensate the first order aberration of the eye E and/or the optical unit 9a to compensate the second order spherical aberration of the eye E and/or the optical unit 9b to compensate the cylindrical second order aberration of the eye E and/or the adaptive optic/mirror 9c to compensate the (remaining) higher order aberrations of the eye E. The remaining wavefront may thus be substantially free of the eye's aberrations. Based on the further compensation the objective first, second and (remaining) higher order aberrations of the eye E may be determined with a high level of accuracy (e.g., in the specific conditions of far and/or near vision distance, e.g., with a preselected diameter of an iris diaphragm 20 which was set by the DPC unit).

[0081] In an example, the control unit 13 may control the shape of the adaptive optic/mirror 9c to compensate not only the (remaining) higher order aberrations but also the first order aberration of the eye, the spherical second order aberration of the eye and/or the cylindrical second order aberration of the eye.

[0082] Moreover, the herein described correction of the aberration (e.g., in particular correcting the corneal refractive aberrations) may ensure a one-to-one correspondence between the wavefront when exiting the cornea of the eye and when impinging on the divider element. This is for example, schematically represented in FIG. 3 that depicts an electromagnetic wave 28 being reflected at the retina 22 of the eye and subsequently passing the eye's lens 23 and the cornea 24 and impinging on the divider element and ultimately a detector 26 of wavefront analyzer 16. In this example, the divider element is a lenslet array 25. When exiting the cornea, the reflected electromagnetic wave may be modeled via various light beams 27 that extend from the cornea to the lenslet array 25. A light beam 27 impinging on a lenslet of the lenslet array 25 may thus originate from a corresponding region of the cornea. To that regard, FIG. 4 shows an enlarged view of the light beams 27 impinging on the lenslets of the lenslet array. However, due to corneal refractive aberrations (or any other higher order aberration) the light beam 27 may be highly deflected such that it does not impinge on its corresponding lenslet of the lenslet array. In another example, the light beams 27 may be deflected by the corneal refractive aberrations in an irregular way such that the electromagnetic wave impinging on the lenslet array 25 does not correspond (at least in part) to the electromagnetic wave when exiting the cornea. The corneal refractive aberrations may thus introduce a significant crosstalk over the desired signal that is assumed to impinge on the divider element for determining the objective refraction. Hence, in this case, the measurement of the wavefront analyzer 16 would be based on a confounded (or even false) signal of the electromagnetic wave which would lead to a less accurate (or even false) determination of the objective refraction. However, the inventive concept may enable to actively correct (and thus suppress) the corneal refractive aberrations via the optical element such that the interfering effect of the corneal refractive aberrations may be significantly reduced during measurement.

[0083] An example of the dynamic pupillometric channel DPC (or DPC unit) is shown in FIG. 5. In this example, the eye E of a patient is enlightened by a chamber of illumination 17, that is controlled by a control unit 13. Control unit 13 may be the same as outlined with reference to FIG. 2. The variation of the level of light projected onto the eye E of the patient may determine the change in the diameter of the iris diaphragm 20 (cf. FIG. 8). The illumination chamber 17 may emit light at one or more wavelengths in the visible spectrum, preferably white light. The illumination chamber may include a lighting system of LEDs that can generate a diffused and/or concentrated lighting stimulus on the eye of the patient E. The illumination chamber may be preferably equipped with a sensor/photodiode 10 to measure the light intensity inside the chamber. The apparatus may include one or more LEDs 3 (also shown as optional in FIG. 2) that may function to image the iris diaphragm of the eye. The one or more LEDs may emit light in a first infrared wavelength, for example, between 700 nm and 800 nm, wherein the one or more LEDs 3 may be located between the eye E and the optical divider DV to illuminate the eye E of the patient to allow to the sensor 8 to capture the image of the iris diaphragm. Notably, the LEDs 3 and their emitted first infrared wavelength should not influence the motility of the iris diaphragm such that the iris diaphragm is not sensitive to radiation in the first infrared wavelength to enable a steady imaging of the iris diaphragm. The image of the eye E, illuminated by the LEDs 3, may go through the optical divider DV (which may be the same as that shown in FIG. 2) and the illumination chamber 17 to reach the sensor 8 (e.g., a CCD and/or CMOS sensor). The sensor 8 may only acquire the light radiation emitted by LEDs 3 and reflected by the eye E. The sensor 8 may be connected to the control unit 13. The control unit 13 may collect the signal detected by the sensor 8 and extract the herein mentioned measurement data of the diameter of the iris diaphragm 20, and consequently adjust the level of light in the illumination chamber 17 in a way that the iris diaphragm diameter 20 is equal to a predefined value with a tolerance to be selectively set, for example, via a man/machine interface. In combination to said control of the diameter of the iris diaphragm 20, the ORC and/or the SRC may execute their optometric measurements on the eye E with a predetermined iris diaphragm.

[0084] In an example, the illumination chamber may be equipped with a photodiode 10, positioned internally in the illumination chamber, and connected to the control unit 13, to measure the light intensity. This may enable to detect the level of light of the illumination chamber 17 during the control exercised on the iris diaphragm diameter 20. In an example, upstream of the sensor 8, with respect to the direction of the light radiation that originates from the eye E towards the sensor 8, a telecentric lens 6 may be installed (e.g., in form of a focal doublet, implemented by the optics 6a and 6b), to allow the focusing of the image of the iris diaphragm onto the sensor 8 (e.g., to avoid magnification errors of the image). Between the telecentric lens 6 and sensor 8 a narrow-band filter 7 may be positioned to allow the selective passage of the first infrared wavelength. This may allow for a more accurate extraction of the diameter of the iris diaphragm 20 by means of the control unit (13).

[0085] In an example, the control unit 13 of the DPC may be configured to enable a variation of the quantity of light inside the illumination chamber 17, to vary the diameter of the iris diaphragm 20 to a set value by an automatic or manual procedure (e.g., selectable by an operator). The method of controlling the diameter of the iris diaphragm 20 by the DPC, which is operated by the control unit 13 may include the following steps: [0086] predefining, via an input using a man/machine interface, of the desired reference value of the diameter of the iris diaphragm 20, to execute refractometric measurement (e.g., an objective refraction and/or subjective refraction and/or quality of vision measurement); [0087] acquisition, via a sensor 8, of at least one image of the iris diaphragm in a preselected condition, via a man/machine interface, of the lighting of the illumination chamber 17; [0088] extraction of the value of the diameter of the iris diaphragm 20 in said preselected condition of lighting of the illumination chamber 17.

[0089] The extracted diameter and the predefined reference value may then be compared.

[0090] If they match to within a threshold that may be predefined or at the operator's discretion, the method may end. Otherwise, the operator and/or the DPC may automatically adjust the lighting condition to move closer to the predefined reference value. The acquisition and extraction steps may then be repeated, as well as the comparing step.

[0091] Subsequently, the functionality that can be implemented from the herein mentioned DPC, when equipped with the photodiode 10 is described. In an example, the control unit 13 may be configured, not only to control the dimension of the diameter of the iris diaphragm 20 during the execution of objective refraction and/or subjective refraction and/or quality of vision measurements. The control unit 13 may also be configured to execute measurements of the diameter of the iris diaphragm 20 for several, numerable and possibly predefined, values of illumination of the chamber 17. In this scenario, the photodiode 10, by means of the control unit 13, may allow to set different predefined values of the lighting of the chamber 17 and, to correspondingly determine the size of the diameter of the iris diaphragm 20. Said illumination values may be determined in the range that varies between the photopic condition of the patient, that is in the condition of maximum environmental lighting (for example 100.000 lux), and the scotopic condition, that is absolute darkness (for example 0 lux). In an example, the control unit 13 may be suitable to allow multiple acquisitions (that may be repeated) of the value of the diameter of the iris diaphragm 20, with the purpose to detect the dynamic stabilization of the iris diaphragm for each predefined condition of lighting and therefore, to allow the detection of the average diameter of the iris diaphragm 20 for each predefined condition of illumination. Notably, the DPC may enable the detection of the iris diaphragm average and/or maximum and/or minimum diameter, as well as related angles of orientation with respect to a predefined reference system.

[0092] The DPC may include an optical divider 5, which may be totally reflective in the first infrared wavelength that images the eye E by means of the LEDs 3 such that the image is transmitted via the first infrared wavelength onto the sensor 8. However, the optical divider 5 may be totally transparent in a second infrared wavelength, for example, for a wavelength between 800 nm and 900 nm, to allow the injection of the second infrared wavelength onto the retina 22 of the eye E which may be focused thereon. The laser diode 4 may be the emitter of the second infrared wavelength which may be guided onto the retina 22 of the eye E to allow the execution the objective refractometric measurement by means of the ORC unit as described herein. The laser diode 4 may also include any other light source that is suitable to execute the objective refractometric measurement (e.g., a light emitting diode, any other types of laser light sources) and may thus not be limited to a laser diode, as such.

[0093] Coming back to the ORC unit of FIG. 2 it should be noted that the filter 15 in front of the wavefront analyzer 16 is a pass-band filter that allows the exclusive transmission of the second infrared wavelength (e.g., emitted from the laser diode 4 of the DPC unit) into the wavefront analyzer 16.

[0094] Subsequently, an interplay of the DPC unit, the ORC unit and the SRC unit of the exemplary apparatus is explained. In an example, the optical divider 11 shown in FIG. 2 may separate the optical path i2 of the ORC and the optical path i3 of the SRC. The optical divider 11 may be totally reflective to light that is used for the optical path i3 of the SRC for performing a subjective refraction, and totally transparent in the second infrared wavelength (i.e., light emitted from the laser diode 4), to allow the transmission of the second infrared wavelength into the wavefront analyzer 16, to perform the objective refractometric analysis, as per the optical path i2 of the ORC. This example should demonstrate that the subdivision between channels shown in FIG. 1 is an example to illustrate a schematic model of the disclosed embodiments. The laser diode 4 that emits an electromagnetic wave (in the second infrared wavelength) that is to be reflected at the retina of the eye may also be included in the ORC unit and/or the SRC unit.

[0095] Furthermore, FIG. 6 shows details of an exemplary SRC unit. It should be noted that in the modular example of the apparatus, the DPC, the SRC and the ORC can be combined as shown in FIG. 7. The SRC unit may share in this example a part of its optical path i3 with a part of the optical path i2 of the ORC. While the present disclosure also includes an SRC unit as a separate apparatus, for the sake of simplicity, its details will be described with reference to FIG. 7.

[0096] The SRC unit may implement means and functions to execute the subjective refraction determination of the eye E and the determination of the quality of vision of the eye E. As a main component to perform the subjective refraction determination, the SRC unit may include the display 14 that may display various signs, shapes, images. In other examples, the SRC unit may not include a display. The optical path of the SRC unit may be connected to a part of the ORC unit via the optical divider 11, which can be seen in FIG. 7. The optical divider 11 may separate the optical path i2 of the ORC and the optical path i3 of the SRC. The optical divider 11 may, for example, be totally reflective in the white light, to allow the reflection into the eye E of the image of the display 14 that is used to perform the analysis of the subjective refraction. The optical divider 11 may be totally transparent in the second infrared wavelength, to allow the transmission of the second infrared wavelength into the wavefront analyzer 16, to perform the objective refractometric analysis, as per the optical path i2 of the ORC.

[0097] As seen in FIG. 7 for an exemplary apparatus, the SRC unit may share with the ORC unit, the focus lens 18, the group of tilting mirrors 21, the optical correction group 9 and the optical divider 11 described herein. Hence, the light that is coupled into the eye E over the SRC unit (e.g., an image of the display 14) may be adapted via the tilting mirrors 21, as well as the optical correction group 9 (which may be the parts of the optical element that is configured to compensate an aberration of the eye). The visual perception of the patient looking into the subjective refraction channel SRC may thus be adapted which enables performing a subjective refraction determination. In another example, the ORC unit and SRC unit can also be implemented independently from each other.

[0098] The subjective refraction of the eye E and the quality of vision of the eye E may be determined via the SRC unit in far distance vision condition and/or in accommodated near distance vision condition by means of the remoter lens 12 (which may include an afocal doublet, implemented by the optics 12a and 12b) to stimulate the lens 23 of the eye E for far distance vision or to accommodate for near distance vision, preferably at a preselected diameter of the iris diaphragm 20. The display 14 may project the image of the display on the remoter lens 12. The image projected by the display 14 may be adapted to simulate the vision of the display 14 to an eye E both in “far vision” and “near vision” conditions. The apparatus may thus be configured to adapt an image the eye perceives of the display 14 to a remote location, as well as a closer location to inflict the “far vision” and/or “near vision” conditions. The stimulation with respect to a “far vision” or “near vision” may also be performed for the ORC unit when performing an objective refraction determination (since also for performing the objective refraction the display 14 may be used to have the patient focus on a certain displayed object).

[0099] The control unit 13 (and/or an operator communicating to the control unit 13 via a man/machine interface) may iteratively control the display 14 and the optical correction group 9, according to the feedback of the patient, to determine the subjective refraction and the quality of vision of an eye E both in “far vision” and “near vision” conditions. The subjective refraction examination may be performed at a preselected diameter of the iris diaphragm 20 via the mechanism of the DPC unit described herein.

[0100] The evaluation of the quality of vision of the patient (e.g., in conditions of controlled diameter of the iris diaphragm 20) can be executed by projecting one or more tests on the display 14 which may permit to evaluate interactively, as a function of the feedback of the patient in relation to the test, the quality of vision in conditions of controlled diameter of the iris diaphragm 20. The test displayed on the display 14 may include a “Contrast Sensitivity Chart”, a visual acuity test, etc.

[0101] For illustrative purposes FIG. 8 displays an iris diaphragm diameter that may be controlled for the ORC and/or SRC measurements as described herein.

[0102] The disclosed embodiments can be realized very conveniently via a computer program that includes coding means for the realization of one or more steps of the method when this program is executed on a computer. Therefore, it is intended that the scope of protection is extended to said program for computers and additionally to means readable by computers that include a recorded message, said means readable with a computer include means of coding of the program for the realization of one or more steps of the method, when said program is executed on a computer.

[0103] Some realization variants to the non-limiting example described are possible, without exiting the scope of the present disclosure.

[0104] From the description mentioned above, the expert in the field can realize the objects of the present disclosure without introducing further construction details. The elements and the characteristics illustrated in the preferred different forms of realization can be combined with each other without exiting the scope of the present application. What is described with reference to the state of the art, unless specifically excluded, must be considered in combination with the characteristics of the disclosed embodiments, forming an integral part of the disclosed embodiments.