METHOD AND APPARATUS FOR MEASURING PROPERTIES OF THE EYE USING A VIRTUAL IMAGE

A technique for evaluating the topography of a cornea, which utilizes a virtual image of a keratoscope pattern. The topography system includes a structured light source to create the keratoscope pattern or another diagnostic pattern, an optical assembly to focus the created pattern upon the cornea, and for capturing the image reflected off the patient's eye and directing the reflected image towards an imaging system for processing. Light emitted by the light source is preferably not in the visible range, to minimize discomfort to the patient. Since the topography is evaluated with a projected virtual image, there is no nose or brow shadow, thereby alowing better corneal coverage. The optical system includes an aperture stop which is preferably conjugate with a point behind the corneal surface approximating the center of a normal cornea. Thus, wide angle capture is achieved as reflected rays reaching the imaging system appear as if they originated at the center of the cornea. A pupil detection mechanism is disclosed which is performed independently of the diagnostic pattern illumination, thereby facilitating pupil detection. In an alternate embodiment, the diagnostic pattern is generated using a variable light pattern generator, which provides flexibility in selecting target images to achieve various diagnostic abilities. The disclosed topography system can be reconfigured to serve as a visual field measuring device, or a perimeter.