Apparatus and method for capturing a visual field of a person having a scotoma

Abstract

A method and an apparatus for capturing a visual field of a person having a scotoma, in particular a central scotoma, are disclosed. The method includes continuously capturing the eye alignment of the person with a capturing unit, sampling the visual field of the person point-by-point to determine points suitable and not suitable for sight in the visual field of the person, finding the scotoma as a region with a multiplicity of points not suitable for sight, calculating an outer boundary line of the scotoma, calculating an outer enveloping curve, which surrounds the outer boundary line of the scotoma at a predetermined distance, and displaying the outer enveloping curve on a display unit. The enveloping curve is perceivable by the person on the display unit as a frame of the scotoma.

Claims

1. A method for capturing a visual field of a person having a scotoma, the method comprising: continuously capturing an eye alignment of the person with a capturing unit; sampling a visual field of the person point-by-point to determine a plurality of points suitable for sight and a plurality of points not suitable for sight in a visual field of the person; finding the scotoma as a region with the plurality of the points not suitable for sight; calculating an outer boundary line of the scotoma; calculating an outer enveloping curve, which surrounds the outer boundary line of the scotoma at a predetermined distance; and displaying the outer enveloping curve on a display unit based on the continuously captured eye alignment, wherein the outer enveloping curve is perceivable as a frame of the scotoma by the person in case of alignment of an eye of the person onto the display unit, wherein the predetermined distance is an angular diameter of between 0.3° and 0.8°.

2. The method according to claim 1, further comprising: determining a position of a preferred retinal locus for fixation.

3. The method according to claim 1, further comprising: implementing the point-by-point sampling of the visual field of the person while the person fixates on a fixation point being permanently displayed on the display unit with a preferred retinal locus for fixation.

4. The method according to claim 3, further comprising: implementing the point-by-point sampling by intermittently displaying a sampling point on the display unit, wherein individual points of the visual field are successively captured in polar coordinates with a distance ρ and an angle θ in respect of the preferred retinal locus for fixation during the point-by-point sampling with the sampling point.

5. The method according to claim 4, further comprising: capturing n points (ρ, θ) by questioning the person in relation to a subjective visibility P of n points displayed on the display unit; and forming at least one of: a 3×n matrix with entries for (ρ, θ, P) for the n captured points (ρ, θ); or a visual field map as a graphical representation of the n captured points (ρ, θ).

6. The method according to claim 3, further comprising: determining a fixation stability from the continuously captured eye alignment as a measure of a quality of the fixation by the preferred retinal locus for fixation on the fixation point displayed on the display unit.

7. The method according to claim 4, wherein a correction of the polar coordinates of a point (ρ, θ) in the visual field is implemented by the continuously captured eye alignment should the fixation point at a moment of sampling the sampling point not be fixated by the preferred retinal locus for fixation.

8. The method according to claim 1, further comprising: recording an image of a fundus of the eye of the person; determining a position of a fovea from the image of the fundus of the eye; and storing at least one of the image of the fundus of the eye or the position of the fovea.

9. The method according to claim 2, further comprising: determining an optimal region for a specific visual task from points suitable for sight in the visual field of the person as a replacement for the preferred retinal locus for fixation.

10. The method according to claim 2, further comprising: storing current data of the person, wherein the stored current data includes a time of the respective determination for the eye or the eyes of the person, and at least one of the continuously captured eye alignment, the points suitable for sight in the visual field of the person, the points unsuitable for sight in the visual field of the person, the outer boundary line of the scotoma, the outer enveloping curve, the position of the preferred retinal locus for fixation, the position of the fovea, or the optimal region for a specific visual task as current data of the person, and producing a statement in relation to at least one of a further development of the scotoma of the person, the position of the preferred retinal locus for fixation of the person, or the optimal region of the person for a specific visual task from at least one of the current data of the person, from earlier correspondingly determined data of the person, or from correspondingly determined data of other persons.

11. The method according to claim 10, wherein the statements in relation to at least one of the further development of the scotoma of the person, the position of the preferred retinal locus for fixation of the person, or the optimal region of the person for a specific visual task are produced with artificial intelligence from the at least one of the current data of the person, from earlier correspondingly determined data of the person, or from correspondingly determined data of other persons.

12. The method according to claim 1, wherein the scotoma is a central scotoma.

13. An apparatus for capturing a visual field of a person having a scotoma, the apparatus comprising: a capturing unit for continuously capturing an eye alignment of the person, a display unit for displaying visual information, wherein the display unit is arranged with respect to a position of the eye of the person in at least one of a defined or a determinable spatial relationship, and a control unit for carrying out the method according to claim 1.

14. The apparatus according to claim 13, wherein the scotoma is a central scotoma.

15. The apparatus according to claim 13, wherein the display unit is a screen, and wherein the apparatus further comprises at least one of: means for placing a head of the person in a position that is defined relative to the screen; or means for determining a position of the head relative to the screen.

16. The apparatus according to claim 13, wherein the display unit is a spherically formed screen.

17. The apparatus according to claim 13, wherein the display unit and the capturing unit are provided in a head unit that is fastened to the head of the person.

18. A computer program stored on a non-transitory computer storage medium and having program code that is executable on a processor for carrying out the method according to claim 1.

19. A non-transitory computer storage medium having a computer program according to claim 18 stored thereon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure will now be described with reference to the drawings wherein:

(2) FIG. 1 shows a temporal sequence for point-by-point sampling of the visual field;

(3) FIG. 2 shows a visual field map as a graphical representation of the subjective visibility P of the n captured points (ρ, θ);

(4) FIG. 3 shows the visual field map (VFM) with the outer boundary line of the scotoma;

(5) FIG. 4 shows a further representation of the visual field map with two additionally plotted optimal preferred retinal loci for fixation for two different specific visual tasks; and

(6) FIG. 5 shows a magnified schematic illustration of the scotoma with an outer boundary line and an outer enveloping curve.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) FIG. 1 shows a temporal sequence of the point-by-point sampling of the visual field. Here, a display unit 1, in particular a screen, is shown at three different successive times A, B, and C. A person is instructed to fixate on the fixation point 2, displayed permanently on the display unit 1, with their left and/or right eye. By way of example, the fixation point 2 is configured as a cross. Additionally, a sampling point 3 appears on the display unit 1 for a predetermined period of time at the time B. By way of example, the sampling point 3 is configured as a circular disc and (its center) has a distance ρ from the fixation point 2 and an angle θ in relation to a line typically extending horizontally through the fixation point 2. Thus, the fixation point 2 defines the origin of a polar coordinate system with the line as polar axis 4. The sampling point 3 is located in this polar coordinate system by the polar coordinates (ρ, θ). In addition to displaying the sampling point 3, the person's attention is drawn to the simultaneous display of the sampling point 3 by means of an acoustic or haptic signal. The person is instructed to communicate with a feedback unit (not shown) whether the sampling point 3 is perceived. By way of example, the feedback unit may comprise a button that should be pressed when the sampling point 3 is perceived. After the predetermined period of time has expired, the sampling point 3 disappears (time C). The acoustic or haptic signal also ends. Typically, pressing of the button that takes place after the sampling point 3 has disappeared is captured by the feedback unit and assigned to the sampling point 3 that has disappeared. After the button being pressed has been captured by the feedback unit and/or after a further period of time has expired, the sampling point 3 appears at another location on the display unit 1, typically, once again, for the predetermined period of time (not shown). The display is once again accompanied by the acoustic or haptic signal. After the predetermined period of time has expired, the sampling point 3 disappeares again (not shown). This sequence is carried out for a total of n different locations on the display unit 1. Thus, the subjective visibility P to the person is captured in each case in this procedure for n pairs of polar coordinates (ρ, θ). P can adopt the values of 1 (sampling point 3 is perceivable by the person) or 0 (sampling point 3 is not perceivable by the person). The captured data are stored specifically for the person in a memory unit with the capture time. The captured data can be represented as a 3×n matrix with line-by-line or column-by-column entries (ρ, θ, P).

(8) The captured data can be represented more clearly as a visual field map. FIG. 2 shows a visual field map 10 as a graphical representation of the subjective visibility P of the n captured points (ρ, θ). The visual field map 10 is a representation of the visual field in polar coordinates. Here, the visual field is subdivided into polar sectors 11. The point-by-point sampling of the visual field, described in conjunction with FIG. 1, is carried out in such a way that one sampling point 3 is in each case assigned to a polar sector 11 of the visual field map 10. Here, all polar sectors 11 present in the visual field map 10 can be captured by a sampling point 3 in each case. However, a selection of n polar sectors 11 is typically made for capturing the subjective visibility P. Typically, only polar sectors 11 in the central region and/or in regions in which no subjective visibility (P=0) has already been determined for the person in earlier measurements, and regions with subjective visibility (P=1) adjacent thereto are captured. In the example of FIG. 2, all polar sectors 11 in which the sampling point 3 was not perceivable by the person in each case (P=0) are marked by an “x.” As an alternative or in addition thereto, these sectors can be illustrated using a certain color, e.g., red. In FIG. 2, T represents temporal; N represents nasal. With 16°, a reference value of the eccentricity is specified. However, the measurement of the visual field may also be implemented beyond 16°.

(9) FIG. 3 shows the visual field map 10 of FIG. 2 after the control unit found a scotoma in the visual field of the person from the arrangement of the polar sectors 11 with P=0 and after the outer boundary line 12 of the found scotoma was calculated. The outer boundary line 12 is schematically plotted in the shape of straight pieces in FIG. 3. The straight pieces connect the centers of the edge sectors forming an edge of the scotoma. However, the outer boundary line 12 can also be determined as a continuous smooth line. The outer boundary line 12 can be illustrated using a certain color, e.g., green. Additionally, FIG. 3 plots the position of the preferred retinal locus for fixation P.sub.p. Since the person fixates the fixation point 2 with their preferred retinal locus for fixation P.sub.p, the preferred retinal locus for fixation P.sub.p is the origin of the polar coordinate system. Additionally, a capturing unit can continuously capture the eye alignment Eye(x,y) of the person during the point-by-point sampling described in relation to FIG. 1. The eye alignment Eye(x,y) captured thus can be stored specifically for the person together with the above-described data relating to ρ, θ, and P, in particular with the 3×n matrix, for the capture time. The position of the preferred retinal locus for fixation P.sub.p in relation to the optic axis can be determined in this case by evaluating the eye alignment Eye(x,y) captured by the capturing unit while fixating on the fixation point 2. Additionally, the polar coordinates (ρ, θ) in relation to a sampling point 3 can be corrected in this case should the eye alignment Eye(x,y) during the display of the sampling point 3 not correspond to the preferred retinal locus for fixation P.sub.p of the person. Furthermore, the position of the fovea F is plotted in FIG. 3. The position of the fovea F can be determined by the additional recording of an image from the fundus of the eye of the person. Different imaging methods can be used to this end, for example scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), or fundus photography. The positional relationship between the fovea F and the preferred retinal locus for fixation can be ascertained on the basis of the image of the fundus and the eye alignment Eye(x,y) when fixating on the fixation point 2 by means of the preferred retinal locus for fixation P.sub.p.

(10) FIG. 4 shows a further representation of the visual field map with two additionally plotted optimal preferred retinal loci for fixation for two different specific visual tasks. A first optimal preferred retinal locus for fixation P.sub.v1 can be calculated by the control unit for a first specific visual task v1. Accordingly, a second optimal preferred retinal locus for fixation P.sub.v2 can be calculated by the control unit for a second specific visual task v2. The first optimal preferred retinal locus for fixation P.sub.v1 and the second optimal preferred retinal locus for fixation P.sub.v2 are plotted in FIG. 4. By way of example, the first optimal preferred retinal locus for fixation P.sub.v1 is optimized for a visual task that requires a position of the preferred retinal locus for fixation below the scotoma, in particular for reading a text. By way of example, the second optimal preferred retinal locus for fixation P.sub.v2 is optimized for a visual task that requires a position of the preferred retinal locus for fixation in the vicinity of the fovea F. Furthermore, the control unit can calculate first translation variables ρ.sub.Pv1 and θ.sub.Pv1 for a translation of the present preferred retinal locus for fixation P.sub.p to the first optimal preferred retinal locus for fixation P.sub.v1 and second translation variables ρ.sub.Pv2 and θ.sub.Pv2 for a translation of the present preferred retinal locus for fixation P.sub.p to the second optimal preferred retinal locus for fixation P.sub.v2. The first translation variables (ρ.sub.Pv1, θ.sub.Pv1) and the second translation variables (ρ.sub.Pv2, θ.sub.Pv2) are likewise plotted in FIG. 4.

(11) FIG. 5 shows a magnified schematic illustration of the scotoma. The control unit can calculate an outer enveloping curve 13 on the basis of the outer boundary line 12. The outer enveloping curve 13 is calculated in such a way that it surrounds the outer boundary line 12 at a predetermined distance. The predetermined distance typically approximately has an angular diameter of 0.5°.

(12) The outer enveloping curve 13 can be displayed on the display unit 1 with the continuously captured eye alignment Eye(x,y) being taken into account in such a way that the outer enveloping curve 13 is perceivable as a frame of the scotoma by the person in the case of any alignment of the eye onto the display unit 1. As a result, the person can perceive the outer enveloping curve 13 with regions of the intact retina that immediately surround the scotoma. Thus, the outer enveloping curve 13 frames the region of the scotoma in the perception of the person.

(13) Displaying the outer enveloping curve 13 as a frame of the scotoma provides precise and intuitive feedback for the person in respect of the size and shape of the scotoma.

(14) Further, training of the preferred retinal locus for fixation P.sub.p of the person can be carried out by means of the display unit 1 while the outer enveloping curve 13 is perceivable as a frame of the scotoma on the display unit 1 at all times by the person, as described above. By way of example, training of the preferred retinal locus for fixation P.sub.p is carried out with the goal of displacing the position of the preferred retinal locus for fixation P.sub.p to the first optimal preferred retinal locus for fixation P.sub.v1 for the specific visual task v1. The outer enveloping curve 13 can be displayed on the display unit 1 here, in addition to a virtual reality or augmented reality scenario.

(15) It was found that the combination of a virtual reality or augmented reality scenario with the display of the outer enveloping curve 13 as a frame of the scotoma makes the training of the preferred retinal locus for fixation P.sub.p particularly effective, in particular when using a head-mounted display as a display unit 1.

(16) The foregoing description of the exemplary embodiments of the disclosure illustrates and describes the present invention. Additionally, the disclosure shows and describes only the exemplary embodiments but, as mentioned above, it is to be understood that the disclosure is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the concept as expressed herein, commensurate with the above teachings and/or the skill or knowledge of the relevant art.

(17) The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “having” or “including” and not in the exclusive sense of “consisting only of.” The terms “a” and “the” as used herein are understood to encompass the plural as well as the singular.

(18) All publications, patents and patent applications cited in this specification are herein incorporated by reference, and for any and all purposes, as if each individual publication, patent or patent application were specifically and individually indicated to be incorporated by reference. In the case of inconsistencies, the present disclosure will prevail.

LIST OF REFERENCE SIGNS

(19) 1 Display unit 2 Fixation point 3 Sampling point 4 Polar axis 10 Visual field map 11 Polar sector 12 Outer boundary line 13 Outer enveloping curve (ρ, θ) Polar coordinates P Subjective visibility F Fovea Eye(x,y) Continuously captured eye alignment P.sub.p Preferred retinal locus for fixation v1 First specific visual task v2 Second specific visual task P.sub.v1 First optimal preferred retinal locus for fixation P.sub.v2 Second optimal preferred retinal locus for fixation (ρ.sub.Pv1, θ.sub.Pv1) First translation variables (ρ.sub.Pv2, θ.sub.Pv2) Second translation variables