Keratometer having peripheral light entrance and exit paths
US4540254A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 26, 1982 |
| Grant date | Sep 10, 1985 |
| Priority date | — |
| Expiry date | Oct 26, 2002 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/107
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A keratometer is disclosed in which at least some of the light entrance and exit paths have both peripheral entrance and exit paths. Eye positional information and sphere, cylinder and axis information for each sampled area (preferably in the order of 3) are obtained by analysis of the reflected and returned light. Sample of a multiplicity of areas on the eye occurs simultaneously without eye panning and generates a topographical measurement of the eye useful for contact lens fitting eliminating most of the incidence of refit on patients in placement of prescribed contact lenses. In one embodiment, a moving boundary locus sweeps an area of light emission from a plurality of coded, spaced apart point light sources. The area of light swept is imaged from the source to the cornea. The locus in its occulting sweep is incident upon the eye at a conjugate point image and reflected from the eye in a diverging light bundle to a plurality of detectors each with its own aperture for sampling the image of that part of the moving boundary locus which is deflected by the particular eye curvature and spacing to the detector aperture. In another embodiment, multiple apertures each image a plurali…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.