Other

Orbtek, Inc.

Richard K Snook

A video Keratometer/Pachymeter comprising an array of illuminated points disposed in concentric circles around the optical axis of a television camera for definition of corneal surface contour by a method similar to the well know Placido, except that the isolated point ring format provides unambiguous back ray trace information to eliminate errors inherent in the prior art, in combination with a projected pattern of discrete points to elicit Tyndall images for definition of both anterior and posterior corneal surface by triangulation using multiple television cameras viewing the reflected and Tyndall images, substraction of a view of the eye with neither pattern superimposed as well as each pattern in sequence for isolation of the data containing points from the general clutter of background pictorial information.

Keratometer/pachymeter

This invention relates to certain improvements in the art of keratometry and, more particularly, to the use of television techniques to determine the shape of the corneal surface of an eye in essentially real-time. Paired television images of diffuse reflections from the cornea are produced by projecting an infra-red illuminated pattern onto the cornea. These diffuse reflections are compared by triangulation to define the corneal contour. The resultant data are processed by a conventional microcomputer to derive surface contour for display, the shape data so generated in a form for instant use. Compensation for image brightness at each location is provided by altering projected image brightness to compensate for inherent non-linearity of diffuse image brightness versus position in the image plane. The liberalization reduces the complexity of the digital signal processing required for producing a contour map of the cornea. The present invention specifically relates to devices that are used in clinical practice.

Keratometry system and method for measuring physical parameters of the

This invention relates to certain improvements in the art of keratometry and, more particularly, to the use of television techniques to determine the shape of the corneal surface of an eye in essentially real-time. Paired television images of diffuse reflections from the cornea are produced by projecting an infra-red illuminated pattern onto the cornea. These diffuse reflections are compared by triangulation to define the corneal contour. The resultant data are processed by a conventional microcomputer to derive surface contour for display, the shape data so generated in a form for instant use. Compensation for image brightness at each location is provided by altering camera video amplifier gain on a pixel by pixel basis, thereby linearizing the response in photometric units. The linearization reduces the complexity of the digital signal processing required for producing a contour map of the cornea. The present invention specifically relates to devices that are used with surgical microscopes.

Surgical keratometer system for measuring surface topography of a cornea

An ophthalmic instrument, in the nature of a pachymeter or densitometer, and which is used for ascertaining the thickness and relative optical density of the cornea of the eye on a real time basis. The instrument comprises a television camera and a multiple Scheimpflug corrected slit projector and an associated processing and display system. A number of digitally encoded television images of the optical section of the cornea are subjected to digital analysis. A density map may be constructed from the data derived in the digital analysis and produced for display either by a printer or display member. The display may be a three-dimensional plot of the frontal surface shape, local thickness, posterior surface contour and optical density of the cornea. A method of using the ophthalmic instrument and of making ophthalmic determinations is also disclosed.

Ophthalmic instrument and method of making ophthalmic determinations

An ophthalmic pachymeter which is highly effective in aiding in the determination of thickness and the optical density of the cornea of an eye on a real-time basis. The pachymeter therefore lends itself to effective employment in aiding in radial keratotomy and other surgical procedures with respect to the eye. The ophthalmic pachymeter of the invention has three major subsystems which include a television camera, a multiple slit projector and an associated processing and display system. In a broad form, the invention comprises illuminating a selected portion of the cornea, moving a slit across the cornea and generating Tyndall image ray paths for enabling analysis of the optical density of the cornea and the thickness of the cornea. This is accomplished through a series of digitally-encoded television images of the optical section of the cornea produced by a multiple slit projector and which images are then subjected to digital analysis. A locus of each of the significant elements of the reflected image of the anterior portion of the eye is defined. In this way, the optical character of the cornea/air interface is compared with the corrected reflectance of the stroma and the endothelium, in order to determine relative transparency. A density map may be constructed in parallel slices for display as a three-dimensional plot of the frontal surface shape of the cornea and for defining and displaying the local thickness, the posterior surface contour, and the optical density of the cornea.

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Tucson, AZ, United States of America

Richard K Snook