Multi-camera corneal analysis system
AssigneeEyesys Technologies, Inc.
InventorsEdwin J. Sarver, Henry D'Souza
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Abstract
The invention relates to the art of corneal topography. More specifically, the invention provides many methods and apparatuses for advancing the ease and accuracy of corneal topography. In addition to a front-view camera, one embodiment provides a side (temporal) view camera for viewing the cornea or other reflective surface. The side-view camera may capture a true image of the cornea as well as a reflected placido pattern. The information contained in these images provides capability to automatically find the apex, location of the limbus, vertical profile and curvature out to the limbus. These abilities lead to improved methods for autocalibration and autopositioning as well as other advantages in the field of corneal mapping.
Claims32
An improvement upon apparatus for measuring a radius of curvature of a human cornea, said cornea having an apex, said apparatus including (A) means for reflecting an image on said cornea, (B) a front-view camera subsystem having an optical axis and a field of view that includes said cornea, said front-view camera subsystem including means for generating a digitized representation of said image, and (C) a processor subsystem programmed to process said digitized representation to produce an estimate of said radius of curvature;
- the improvement comprising:
- (a) a first side-view camera subsystem:
- (1) having a field of view that includes said cornea,
- (2) including means for generating a digitized representation of said image,
- (3) being rigidly positioned relative to said front-view camera subsystem, and
- (4) having an optical axis that is substantially orthogonal to the optical axis of said front-view camera subsystem;
- (b) the optical axes of said front-view camera subsystem and of said first side-view camera subsystem collectively defining a coordinate system having an origin defined by the intersection of those optical axes;
- (c) a processor subsystem programmed:
- (1) to analyze said digitized representations generated by said front-view camera subsystem and said first side-view camera subsystem and to generate an error signal representing a displacement of said apex relative to said origin, and
- (2) to generate a positional signal representative of the position of said apex relative to said coordinate system;
- and
- (d) means to generate a periodically-updated visual display of said positional signal.
An apparatus for topographically mapping a reflecting surface, said reflecting surface having an apex, comprising:
- (a) means for reflecting an image on said reflecting surface;
- (b) a front-view camera subsystem having an optical axis and a front field of view that includes said reflecting surface, said front-view camera subsystem including means for generating a first digitized representation of said image;
- (c) a first processor subsystem programmed to process said first digitized representation to produce topographic data of said reflecting surface, including estimates of radii of curvature of said reflecting surface at a plurality of points;
- (d) a first side-view camera subsystem having:
- (1) a field of view that includes a first side view of said reflecting surface,
- (2) means for generating a second digitized representation of said image, and
- (3) an optical axis that is substantially orthogonal to the optical axis of said front-view camera subsystem;
- (e) the respective optical axes of said front-view camera subsystem and said first side view camera subsystem collectively defining a coordinate system having an origin;
- (f) said first side-view camera subsystem and said front-view camera subsystem collectively comprising a camera assembly;
- and
- (g) a second processor subsystem programmed to analyze said digitized representations generated by said front-view camera subsystem and said first side-view camera subsystem and to generate an error signal representing a displacement of said apex relative to said origin.
A keratometric apparatus for topographically analyzing a reflecting surface, comprising:
- (a) means for reflecting an image off said reflecting surface;
- (b) a front-view camera for generating a first digitized signal representing a front view of said image;
- (c) a side-view camera for generating a second digitized signal representing a side-view of said image;
- and
- (d) a processor subsystem for receiving said front-view digitized signal and said side-view digitized signal and processing said signals for repeatably positioning said front-view camera and said side-view camera in relation to said reflecting surface and to estimate the radii of curvature at multiple points on said reflecting surface.
A method of finding the apex of a reflecting surface in a multi-camera corneal analysis system having a camera assembly including a side-view camera and a front-view camera comprising:
- (a) using said side-view camera to capture a side-view image of said reflecting surface;
- and
- (b) determining an actual apex location by detecting a leading edge of said side-view image.
A method of automatically calibrating a multi-camera corneal analysis system having a camera assembly including a front-view camera and a side-view camera, comprising:
- (a) using said side-view camera to detect an actual Z-axis location of an apex of a reflecting surface on a cornea with respect to a desired location of said apex;
- (b) using said front-view camera to detect an actual X-axis and Y- axis location of said apex with respect to said desired location of said apex;
- and
- (c) generating an error signal for each axis, X, Y and Z, said error signals defined by a difference between said actual location and said desired location.
A keratometric apparatus for examining the cornea of an eye by means of a reflected image on the cornea of an illuminated target, said apparatus comprising:
- a first camera positioned with its optical axis aligned with the optical axis of the eye to capture a front view of the cornea and the reflected image;
- and
- a second camera positioned on one side of the cornea, with the optical axis of the second camera intersecting the optical axis of the first camera substantially orthogonally, to capture a profile view of the cornea and said reflected image.
A keratometric method for examining an eye which includes forming a reflected image of an illuminated target on the cornea of the eye, said method comprising:
- capturing a front view of the cornea and said image on a first camera whose optical axis is aligned with the optical axis of the eye;
- and
- capturing a side view of the cornea and said image on a second camera which is positioned to one side of the cornea and whose optical axis is substantially orthogonal to said optical axis of said first camera.
Dependencies are inferred from the claim text.