Method and device for ocular alignment and coupling of ocular structures
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.
1. A system for defining a reference axis of a patient's eye in an external coordinate system, comprising:
an eye guide adapted to be coupled to the patient's eye;
a light source for directing a light beam on a reflective surface associated with the patient's eye;
an imaging system for recording an image of a limbus of the patient's eye and an image formed by a reflection of the light beam on the reflective surface; and
a guide-alignment assembly configured to adjust the eye guide until a position of the reflection is coincident with a center of the limbus.
2. The system of claim 1 , wherein the reflective surface is a cornea of the patient's eye.
3. The system of claim 1 , wherein the reflective surface a reflective surface of a contact member for positioning on a surface of the patient's eye.
4. The system of claim 1 , wherein, when the position of the reflection is coincident with the center of the limbus, an axis normal to a cornea at a corneal center defines the reference axis.
5. The system of claim 1 , wherein a guide-alignment assembly is configured to adjust the patient's eye by adjusting the eye guide.
6. The system of claim 1 , wherein the imaging system comprises a camera.
7. The system of claim 1 , wherein the imaging system comprises a photodetector.
8. The system of claim 1 , further comprising a processor operatively connected to the imaging system and the guide-alignment assembly.
9. The system of claim 1 , further comprising a processor configured to, from the image of the limbus, determine the center of the limbus of the patient's eye in the external-coordinate system.
10. The system of claim 1 , further comprising a processor configured to, from the image of the reflection of the light beam on the reflective surface, determine when the position of the reflection image is coincident with the center of the limbus.
11. The system of claim 1 , further comprising a processor configured to:
determine 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,
if variation from true centering is determined, construct a coordinate transform between the actual and centered positions of the eye guide,
with the eye guide moved to and held at its aligned position, and applying the coordinate transform if necessary, determine the position of the eye with respect to the reference axis,
determine a treatment axis or axes along which a therapeutic beam will be aimed at a target region of the eye.
12. The system of claim 1 , further comprising a processor configured to generate positioning signals for positioning a diagnostic or therapeutic device at a selected position and angle with respect to the reference axis.
13. The system of claim 1 , further comprising a display monitor for displaying to a user, an image of the patient's eye and attached eye guide, information about the extent of alignment between the eye guide and light beam, and a virtual image of the reference axis.
14. The system of claim 1 , further comprising an image processor, wherein the processor is configured to fit the image of the limbus to a circle and determine the center of the circle.
15. The system of claim 1 , wherein the eye guide is configured to be stabilized on the eye by an application of negative pressure between the eye guide and eye.
16. The system of claim 1 , wherein the eye guide comprises an eye-contact portion configured to operatively contact an anterior surface of the eye, and a support portion operatively engageable to the eye-contact portion, and wherein eye-contact portion and the support portion are configured to engage releasably, the release being upon voluntary or involuntary motion by the patient.
17. The system of claim 1 , wherein the guide-alignment assembly comprises 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 reference axis.
18. The system of claim 1 , further comprising a head restraint configured to stabilize the patient's head.
19. The system of claim 1 , further comprising an X-ray device configured to emit an X-ray beam.