Infrared photoretinoscope
US4834528A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1986 |
| Grant date | May 30, 1989 |
| Priority date | — |
| Expiry date | Aug 15, 2006 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/145
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A retinoscope utilizing a plurality of infrared light sources each positioned at a difference distance, or eccentricity, from the optical axis of a camera is disclosed. The plural light sources are scanned while the fundus reflex is observed. Whether or not a reflex can be detected depends on the defocus of the eye relative to the camera, the pupil size, the eccentricity of the light source from the optical axis, and the camera-to-subject distance. The light sources are preferably light emitting diodes which are flashed repeatedly and sequentially. One-half of the camera aperture is occluded to permit determination of the amount and the direction of defocus. By noting which LED just creates a crescent of light in the pupil, and by measuring the pupil diameter, the relative defocus of the eye is determined.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.