Method and apparatus for analysis of corneal shape
US4420228A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 27, 1980 |
| Grant date | Dec 13, 1983 |
| Priority date | — |
| Expiry date | Jun 27, 2000 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/107
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
An analysis of the corneal shape through the combination of several keratometer measurements is disclosed. The eye is preferably scanned to a nasal angular position, a central angular position and a temporal angular position. The central position is straight ahead along the patient's line of sight. The temporal and nasal positions are in the broad range of up to 5.degree. to 22.degree.; the intermediate range of 10 to 15.degree.; and the narrow range of 12.degree. to 14.degree. on either side. Measurements in sphere, cylinder and axes are taken. Astigmatism is in the more preferable format of 0.degree.-90.degree. astigmatism and 45.degree.-135.degree. astigmatism. When each individual point is measured with its respective estimate for sphere and cylinder components, these measurements are fitted to an idealized parameter. Then the three sets of curvature measurements taken at the specified locations are reduced to a set of adjusted, idealized curvatures all fitted to an elliptical model. Thereafter, these fitted values create final corneal shaped parameters, the particular process here including the creation of intermediate parameters. Finally, readings of central "k", corneal shap…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.