Near eye tool for refractive assessment

• US 8,783,871 B2
• Filed: 04/22/2011
• Issued: 07/22/2014
• Est. Priority Date: 04/22/2010
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Raskar, Ramesh, Pamplona, Vitor, de Oliveira Neto, Manuel Menezes, Mohan, Ankit
• Primary Examiner(s): Ben, Loha
• Application Number:
  US13/577,880
• Publication Number:
  US 20130027668A1
• Time in Patent Office: 1,187 Days
• Field of Search: 351/205, 351/208, 351/209, 351/216, 351/236, 351/239, 351/243, 351/246
• US Class Current: 351/239
• CPC Class Codes: A61B 3/032 Devices for presenting test symbols or characters, e.g. test chart projectors A61B3/036 takes precedence

Abstract

In exemplary implementations, this invention is a tool for subjective assessment of the visual acuity of a human eye. A microlens or pinhole array is placed over a high-resolution display. The eye is brought very near to the device. Patterns are displayed on the screen under some of the lenslets or pinholes. Using interactive software, a user causes the patterns that the eye sees to appear to be aligned. The software allows the user to move the apparent position of the patterns. This apparent motion is achieved by pre-warping the position and angle of the ray-bundles exiting the lenslet display. As the user aligns the apparent position of the patterns, the amount of pre-warping varies. The amount of pre-warping required in order for the user to see what appears to be a single, aligned pattern indicates the lens aberration of the eye.

Claims

1. A process for assessing an optical system, said process comprising in combination:

controlling an electronic visual display to display patterns under at least some lenslets or pinholes in an array of lenslets or pinholes, which array is positioned so that light from the electronic visual display passes through the array and reaches the optical system,

controlling the electronic visual display to change the patterns, as seen by the optical system, in accordance with control input,

accepting input indicating that the patterns appear, to the optical system, to form a desired image, and

determining, based on the input regarding apparent formation of the desired image, at least one refractive parameter of the optical system.

2. The process of claim 1, wherein the electronic visual display comprises a liquid crystal display.

3. The process of claim 1, wherein the optical system comprises an eye of a human user.

4. The process of claim 3, wherein the control input and the input regarding apparent formation of desired image are from the human user.

5. The process of claim 3, wherein the control input and the input regarding apparent formation of desired image are from another human user.

6. The process of claim 3, wherein the at least one refractive parameter is a spherical power of the eye.

7. The process of claim 3, wherein the at least one refractive parameter is one of (i) a cylindrical power of the eye and (ii) a cylindrical axis of the eye.

8. The process of claim 3, wherein the at least one refractive parameter is one of (i) a short focus distance of the eye and (ii) a far focus distance of the eye.

9. The process of claim 3, wherein:

the eye'"'"'s refraction is radially symmetric; and

the patterns appear, to the eye, to be aligned when the distance from the lenslets to a virtual object consisting of the patterns is equal to 1/S , where S is the spherical power, in diopters, of the eye.

10. The process of claim 3, wherein:

the eye'"'"'s refraction is radially asymmetric;

the patterns are displayed only under lenslets bisected by a straight line of orientation θ

;

the patterns consist of straight line segments oriented at an angle of (π

/2+θ

); and

the patterns appear, to the eye, to be aligned when the distance from the lenslets to a virtual object consisting of the patterns is equal to 1/(S+C sin²(α

−

θ

)), where S is the spherical power, in diopters, of the eye, C is the cylindrical power in diopters of the eye, and α

is the cylindrical axis of the eye.

11. The process of claim 10, further comprising the steps of:

projecting symmetric accommodation patterns along the eye'"'"'s cylindrical axis, and

determining the eye'"'"'s range of accommodation based on the longest and shortest distances, from the lenslets to the virtual object, at which the symmetric accommodation patterns appear to the eye to be aligned.

12. The process of claim 3, further comprising using a beamsplitter to present both a first image and a second image to the eye at the same time, the first image for providing a cue for the eye to focus at an apparent depth of the first image, and the second image being a test image for assessing the at least one refractive parameter while the eye is focused at that apparent depth.

13. The process of claim 1, wherein the control input and the input regarding apparent formation of desired image are from a computer.

14. The process of claim 1, wherein the patterns have apparent positions relative to each other, as seen by the optical system, and at least some of the apparent positions change.

15. The process of claim 1, wherein at least one of the patterns, as seen by the optical system, has a shape that changes.

16. The process of claim 1, wherein color of the patterns, as seen by the optical system, varies spatially or temporally.

17. The process of claim 1, wherein at least one of the patterns, as seen by the optical system, moves.

18. The process of claim 1, wherein the speed of accommodation of the optical system is determined by controlling the electronic visual display to change the depth of a virtual object consisting of the patterns from one depth to a new depth, and measuring how long it takes for the optical system to accommodate to the new depth.

19. Apparatus comprising, in combination:

an array of lenslets or pinholes, positioned or adapted for being positioned over an electronic visual display so that light from the electronic visual display can pass through the array and reach an optical system, and

at least one processor for;

controlling the electronic visual display to display patterns under at least some lenslets or pinholes in the array;

controlling the electronic visual display to cause apparent positions of the patterns, as seen by the optical system, to move closer together or farther apart, in accordance with control input;

accepting input indicating that the patterns appear, to the optical system, to align to form a single image; and

determining, based on said input regarding apparent alignment, at least one refractive parameter of the optical system.

20. The apparatus of claim 19, further comprising the electronic visual display.

21. Apparatus comprising, in combination:

an array of lenslets or pinholes, positioned or adapted for being positioned over an electronic visual display so that light from the electronic visual display can pass through the array and reach an optical system; and

at least one processor for;

controlling the electronic visual display to display patterns under at least some lenslets or pinholes in the array;

controlling the electronic visual display to change the patterns, as seen by the optical system, in accordance with control input;

accepting input indicating that the patterns appear, to the optical system, to form a desired image; and

determining, based on said input regarding apparent formation, at least one refractive parameter of the optical system.

22. The apparatus of claim 21, wherein the electronic visual display comprises a liquid crystal display.

23. The apparatus of claim 21, wherein the optical system comprises an eye of a human user.

24. The apparatus of claim 23, wherein the control input and the input regarding apparent formation of desired image are from the human user.

25. The apparatus of claim 23, wherein the control input and the input regarding apparent formation of desired image are from another human user.

26. The apparatus of claim 23, wherein the at least one refractive parameter is a spherical power of the eye.

27. The apparatus of claim 23, wherein the at least one refractive parameter is one of (i) a cylindrical power of the eye and (ii) a cylindrical axis of the eye.

28. The apparatus of claim 23, wherein the at least one refractive parameter is one of (i) a short focus distance of the eye and (ii) a far focus distance of the eye.

29. The apparatus of claim 23, wherein the at least one processor is also for performing a step comprising:

controlling the electronic visual display to display the patterns so that, if the eye has radially symmetric refraction, the patterns appear to be aligned when the distance from the lenslets to a virtual object consisting of the patterns is equal to 1/S , where S is the spherical power, in diopters, of the eye.

30. The apparatus of claim 23, wherein the at least one processor is also for performing a step comprising:

controlling the electronic visual display to display the patterns as straight line segments oriented at an angle of (π

/2+θ

) that are under only lenslets bisected by a straight line of orientation θ

, and that appear, to the eye, to be aligned when the distance from the lenslets to a virtual object consisting of the patterns is equal to 1/(S+C sin² (α

−

θ

)), where S is the spherical power in diopters of the eye, C is the cylindrical power in diopters of the eye, and α

is the cylindrical axis of the eye.

31. The apparatus of claim 23, wherein the at least one processor is also for performing a step comprising:

projecting symmetric accommodation patterns along the eye'"'"'s cylindrical axis, and determining the eye'"'"'s range of accommodation based on the longest and shortest distances, from the lenslets to a virtual object, at which the symmetric accommodation patterns appear to the eye to be aligned.

32. The apparatus of claim 23, wherein the at least one processor is also for performing a step comprising:

determining the speed of accommodation of the optical system by controlling the electronic visual display to change the depth of a virtual object consisting of the patterns from one depth to a new depth, and measuring how long it takes for the optical system to accommodate to the new depth.

33. The apparatus of claim 23, further comprising a beamsplitter for presenting both a first image and a second image to the eye at the same time, the first image for providing a cue for the eye to focus at an apparent depth of the first image, and the second image being a test image for assessing the at least one refractive parameter while the eye is focused at that apparent depth.

34. The apparatus of claim 21, wherein the control input and the input regarding apparent formation of desired image are from a computer.

35. The apparatus of claim 21, wherein the patterns have apparent positions relative to each other, as seen by the optical system, and at least some of the apparent positions change.

36. The apparatus of claim 21, wherein at least one of the patterns, as seen by the optical system, has a shape that changes.

37. The apparatus of claim 21, wherein color of the patterns, as seen by the optical system, varies spatially or temporally.

38. The apparatus of claim 21, wherein at least one of the patterns, as seen by the optical system, moves.

39. The apparatus of claim 21, wherein the at least one processor comprises multiple processors, and at least one of the multiple processors is remote from the array.