Method and device for ocular alignment and coupling of ocular structures

• US 8,363,783 B2
• Filed: 04/15/2008
• Issued: 01/29/2013
• Est. Priority Date: 06/04/2007
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Original Assignee: Oraya Therapeutics, Inc.
• Inventors: Gertner, Michael, Arnoldussen, Mark, Herron, Matt, Liang, Junzhong
• Primary Examiner(s): THOMAS, COURTNEY D
• Application Number:
  US12/103,534
• Publication Number:
  US 20090163898A1
• Time in Patent Office: 1,750 Days
• Field of Search: 378/65, 378/205, 606/4, 351/206, 351/246
• US Class Current: 378/65
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: A61B 3/152 for aligning
• CPC Class Codes: A61F 2009/00846 Eyetracking
• CPC Class Codes: A61F 2009/00863 Retina
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: A61F 9/00802 for photoablation
• CPC Class Codes: A61F 9/009 Auxiliary devices making contact with the eyeball and coupling in laser light, e.g. goniolenses apparatus for eye examination A61B3/0008
• CPC Class Codes: A61N 2005/1059 using cameras imaging the patient
• CPC Class Codes: A61N 2005/1091 Kilovoltage or orthovoltage range photons
• CPC Class Codes: A61N 5/1017 Treatment of the eye, e.g. for "macular degeneration"
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam

Abstract

Embodiments provide method and systems for determining or measuring objective eye alignment in an external-coordinate system so as to define a reference axis. Additional embodiments provide a method and system of aligning an objectively determined reference axis of the eye in a selected relationship to a therapeutic axis of an ophthalmic therapeutic apparatus and/or a diagnostic axis of an ophthalmic diagnostic apparatus. Embodiments provide a method and system for planning an ophthalmic treatment procedure based on objective eye alignment in an external-coordinate system so as to define a reference axis of an eye to be treated. The reference axis may be used to position a therapeutic energy component, for example, an orthovoltage X-ray treatment device, e.g., positioned to provide treatment to tissue on the retina, such as the macula.

Claims

1. A method of determining when a subject'"'"'s eye position is aligned with a reference axis in an external coordinate system, comprising:

(a) determining positions of the sclera/cornea boundary (limbus) of the subject'"'"'s eye in the external coordinate system,

(b) from the positions of the sclera/cornea boundary determined in step (a) determining the center of the limbus of the subject'"'"'s eye in the external-coordinate system,

(c) determining the position of an image of a light beam reflected from a reflective surface associated with the subject'"'"'s eye

(d) determining that the subject'"'"'s eye is aligned with the external-coordinate reference axis when the position of the reflection from step (c) is coincident with the center of the limbus from step (b).

2. The method of claim 1, wherein the reflective surface associated with the subject'"'"'s eye includes one of a surface of the cornea, a surface of the lens of the eye, and the surface of the retina.

3. The method of claim 1, wherein the reflective surface associated with the subject'"'"'s eye includes one of a surface of a contact member or contact lens disposed in contact with the surface of the eye, and a surface of a mirror or fiducial element positioned on a contact member disposed in on surface of the eye.

4. The method of claim 1, wherein said determining is carried out with the subject'"'"'s head stabilized in a head restraint.

5. The method of claim 1, wherein step (a) includes recording an image of the subject'"'"'s limbus by an optical detector, and step (b) includes fitting the limbus image to a circle, and determining the center point of the circle.

6. The method of claim 1, wherein determining steps (a)-(c) are carried out by an imaging system disposed in the external coordinate system.

7. The method of claim 6, wherein the reflection from the subject'"'"'s eye is a first Purkinje image formed by reflection of a coherent or focused light beam off the anterior surface of the cornea of the subject'"'"'s eye.

8. The method of claim 7, wherein the optical axis of the coherent or focused light beam is aligned with the imaging system.

9. The method of claim 1, which further includes generating an eye-alignment signal when the subject'"'"'s eye position is aligned with the external-coordinate reference axis.

10. The method of claim 9, which further includes using the eye-alignment signal to attach an ocular positioning and stabilizing device to the subject'"'"'s eye.

11. The method of claim 9, which further includes using the eye-alignment signal to activate a therapeutic beam aimed along a path having a known relationship with the external-coordinate reference system.

12. The method of claim 11, for use in treating macular degeneration, wherein the therapeutic beam is a low-energy collimated X -ray beam, and the therapeutic beam is aimed along a path that intersects the reference axis at a region of the subject'"'"'s eye, and at an angle between about 10-45 degrees with respect thereto.

13. The method of claim 1, wherein the reference axis defines a geometric axis of the subject'"'"'s eye, and the method further includes calculating and/or measuring the distance between the cornea and the retina along this axis.

14. The method of claim 1, for determining the position of intersection of the reference axis with the subject'"'"'s retina relative to a structure of interest on the retina, which further includes the steps of:

(e) determining the position of an image formed by reflection of the light beam in step (c) off the retina of the subject'"'"'s eye, when the position of the reflection image from step (c) is coincident with the center of the limbus image from step (b),

(f) passing a second coherent or focused light beam through the pupil of the subject'"'"'s eye to reflect off a structure of interest in the retina, and

(g) determining the position of the image of the reflection of the second beam in the external coordinate system, relative to the image from step (e) in the external coordinate system.

15. A method of defining a reference axis of a patient'"'"'s eye in an external coordinate system, comprising

(a) determining the positions of the sclera/cornea boundary (limbus) of the subject'"'"'s eye in the external coordinate system,

(b) from the positions of the sclera/cornea boundary in step (a) determining the center of the sclera/cornea boundary of the patient'"'"'s eye in the external-coordinate system,

(c) determining the position of an image formed by reflection of a coherent or focused light beam from a reflective surface associated with the patient'"'"'s eye,

(d) adjusting the position of the patient'"'"'s eye until the position of the reflection image from step (c) is coincident with the center of the sclera/cornea boundary image from step (b), at which position an axis normal to the cornea at the corneal center defines the patient reference axis.

16. The method of claim 15, wherein the reference axis extends from the cornea to a position on the retina which is a maximum distance from the cornea.

17. The method of claim 15, which further includes superimposing the patient reference axis on a three-dimensional model of the eye by aligning the patient reference axis with a model reference axis.

18. The method of claim 15, for conducting a diagnostic or therapeutic procedure on the eye, which further includes positioning a beam of a diagnostic or therapeutic device at a selected position and angle with respect to the patient reference axis.

19. The method of claim 15, which further includes generating an eye-alignment signal when the patient'"'"'s eye position is aligned with an external-coordinate reference axis.

20. The method of claim 19, which further includes using the eye-alignment signal to attach an ocular positioning and stabilizing device to the patient'"'"'s eye.

21. The method of claim 20, which further includes using the eye-alignment signal to activate a therapeutic beam aimed along a path having a known relationship with the external-coordinate reference system.

22. The method of claim 15, for use in treating macular degeneration, wherein the therapeutic beam is a low-energy collimated x-ray beam, and the therapeutic beam is aimed along a path that intersects the reference beam in a macular region of the patient'"'"'s eye, and at an angle between about 10-45 degrees with respect thereto.

23. The method of claim 15, for determining the position of intersection of the reference axis with the patient'"'"'s retina relative to a structure of interest on the retina, which further includes the steps of:

(e) determining the position of an image formed by reflection of the light beam in step (c) off the retina of the patient'"'"'s eye, when the position of the reflection image from step (c) is coincident with the center of the sclera/cornea boundary image from step (b),

(f) passing a second coherent or focused light beam through the pupil of the patient'"'"'s eye to reflect off a structure of interest in the retina, and

(g) determining the position of the image of the reflection of the second beam in the external coordinate system, relative to the image from step (e) in the external coordinate system.

24. A system of defining a reference axis of a patient'"'"'s eye in an external coordinate system, comprising

(a) a light source for directing a coherent or focused light beam on a reflective surface associated with the patient'"'"'s eye,

(b) an imaging system for recording an image of the patient'"'"'s limbus and an image formed by reflection of the coherent or focused light beam from the cornea of the patient'"'"'s eye, and

(c) a processor operatively connected to the imaging system for

(i) from the image of the sclera/cornea boundary, determining the center of the sclera/cornea boundary of the patient'"'"'s eye in the external-coordinate system, and

(ii) from the image of the reflection of the coherent or focused light beam off the reflective surface, determining when the position of the reflection image is coincident with the center of the sclera/cornea boundary image, at which position an axis normal to the cornea at the corneal center defines the reference axis.

25. The method of claim 24, wherein the system further includes a head restraint configured to stabilize the patient'"'"'s head.

26. The system of claim 24, wherein the light source of (a) is a coherent light beam.

27. The system of claim 24, wherein the processor further operates to generate a signal when the coincidence condition in step (ii) is met.

28. The system of claim 27, wherein the processor further operates to generate positioning signals for positioning a diagnostic or therapeutic device at a selected position and angle with respect to the reference axis.

29. The system of claim 24, wherein said imaging system includes a CCD photodetector.

30. The system of claim 29, further comprising an image processor and wherein the processor operates in step (i) to fit the image of the sclera/cornea boundary to a circle, and find the center of the circle.

31. The system of claim 29, further comprising a second processor and wherein the processor operates in step (ii) to determine, at each eye position of the patient eye, whether the center of the patient eye sclera/cornea boundary is the same as the position of the reflection image from the cornea.

32. The system of claim 29, wherein the image system further operates to record reflections of a coherent or focused beam off of the surface of the retina, and the processor further operates to

(iii) determine the position of an image formed by reflection of the light beam in (c) off the retina of the patient'"'"'s eye, when the position of the reflection image off the cornea step is coincident with the center of the sclera/cornea boundary image,

(iv) determine the position of an image formed by reflection of another coherent or focused light beam off a selected structure of interest in the retina, and

(v) determine the position of the image of the reflection of the other beam off the structure of interest in the external coordinate system, relative to the position of the image of the reflection off the retina along the reference axis.

33. A method of placing a patient'"'"'s eye in alignment with a reference axis in an external coordinate system, comprising

(a) placing an ocular guide on a patient'"'"'s eye,

(b) centering the guide with respect to the sclera/cornea boundary of the patient'"'"'s eye,

(c) stabilizing the ocular guide on the eye by applying a negative pressure between the guide and eye,

(d) moving the ocular guide, and thus patient'"'"'s eye, until the ocular guide is aligned with the reference axis, thus to place the patient'"'"'s eye in alignment with the reference axis.

34. The method of claim 33, wherein the ocular guide has an peripheral ring dimensioned to be contained within or substantially coincident with the sclera/cornea boundary of the patient'"'"'s eye, and step (b) includes adjusting the position of the guide until the peripheral ring and sclera/cornea boundary are coaxially aligned.

35. The method of claim 34, wherein said adjusting in step (b) is carried out by manually positioning the ocular guide on the patient'"'"'s eye.

36. The method of claim 33, wherein the negative pressure applied in step (c) is between 20-50 mm Hg.

37. The method of claim 33, wherein step (d) is carried out by position-controlled movement of an external arm pivotally attached to the guide.

38. The method of claim 33, which further includes applying a force that biases the external arm against the patient'"'"'s eye.

39. The method of claim 33, wherein the ocular guide includes a reflector and step (d) includes directing a collimated beam at the reflector and adjusting the position of the guide until the collimated beam and its reflection off the guide mirror are along axes that are symmetrical with respect to the reference axis.

40. The method of claim 39, wherein the beam and reflection axes are coincident with the reference axis.

41. The method of claim 33, which further includes determining the extent to which the eye guide is centered with respect to the sclera/cornea boundary, recording the variation, if any, from true centering, and constructing a coordinate transform between the actual and centered positions of the eye guide, and step (d) includes applying the transform to the position of the eye guide, with just placed in an aligned position, to place the patient'"'"'s eye in alignment with the reference axis.

42. The system of claim 33, wherein the eye guide comprises an eye-contact portion configured to operatively contact an anterior surface of the eye, and a support portion operatively engagable to the eye-contact portion, and wherein eye-contact portion and the support portion are configured to engage releasibly, the release being upon voluntary or involuntary motion by the patient.

43. The method of claim 33, wherein the ocular guide has a curved structure which is centered on an axis extending through the contact member, the ocular guide has an outer reflecting surface normal to and intersected by the center axis of the eye contact member, and step (d) includes directing a collimated beam at the reflecting surface and adjusting the position of the guide until the collimated beam and its reflection off the reflecting surface are along axes that are symmetrical with respect to the reference axis.

44. An image-guided ocular treatment system comprising

(a) a eye guide adapted to be placed on a patient'"'"'s eye, and stabilized on the eye by the application of negative pressure between the eye guide and eye when the guide is approximately centered with respect the sclera/cornea boundary of the patient'"'"'s eye,

(b) a camera for recording an image of the eye guide on the patient'"'"'s eye,

(c) a guide-alignment assembly for detecting alignment between the eye guide, with such stabilized on a patient'"'"'s eye, and an external-coordinate reference axis,

(d) an external arm pivotally attached to the eye guide to hold the eye at a position in which the eye guide is aligned with the external-coordinate reference axis,

(e) a processor operatively connected to the camera and guide-alignment assembly for

(i) determining from the image of eye guide and the sclera/cornea boundary, any variation from true centering of the eye guide on the patient'"'"'s eye,

(ii) if variation from true centering is determined, constructing a coordinate transform between the actual and centered positions of the eye guide,

(iii) with the eye guide moved to and held at its aligned position, and applying the coordinate transform if necessary, determining the position of the eye with respect to the external-coordinate reference axis,

(iv) from the determination in step (iii) determining a treatment axis or axes along which a therapeutic beam will be aimed at a target region of the eye, and

(f) a display monitor operatively connected to the processor for displaying to the user, an image of the patient'"'"'s eye and attached eye guide, information about the extent of alignment between the eye guide and reference beam, and a virtual image of the treatment axis or axis.

45. The method of claim 44, wherein the system further includes a head restraint configured to stabilize the patient'"'"'s head.

46. The system of claim 44, wherein the processor includes stored fundus images, and operates to superimpose those images on the image of the patient'"'"'s eye displayed on the monitor, allowing the user to view the areas of intersection of the therapeutic beam axes and fundus.

47. The system of claim 44, wherein the ocular guide comprises an eye-contact portion configured to operatively contact an anterior surface of the eye, and a support portion operatively engagable to the eye-contact portion, and wherein eye-contact portion and the support portion are configured to engage releasibly, the release being upon voluntary or involuntary motion by the patient.