Method and apparatus for combined cylindrical and spherical eye corrections
US5713892A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 15, 1993 |
| Grant date | Feb 3, 1998 |
| Priority date | — |
| Expiry date | Oct 15, 2013 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61F2009/00872
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A method for performing concurrent spherical and cylindrical corrections to the corneal surface of the eye to reduce myopia and astigmatism. A laser beam irradiates the corneal surface via a variable diameter iris and a slot produced by a pair of translatable blades. The width of the slot and the diameter of the iris are varied as the laser is pulsed to produce a toric ablation of the corneal surface. Alternatively, the laser beam is passed through a succession of apertures in a tilted variable aperture element to produce toric ablation. The total number of laser pulses required to effect both types of correction is equal to the number required for the spherical correction alone, reducing the laser power and the procedure time. The toric ablation produces no steep end walls as with standard cylindrical ablation procedures, thereby eliminating hyperopic shift and minimizing flattening along the ablated cylinder axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.