Correction of presbyopia by photorefractive keratectomy
US5395356A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 1993 |
| Grant date | Mar 7, 1995 |
| Priority date | — |
| Expiry date | Jun 4, 2013 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61F2009/00895
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
Methods and apparatus are disclosed for the correction of presbyopia by reprofiling the cornea to create at least one region having a different focal point, and thereby assist the eye in accommodating for close-viewing conditions. According to the invention, at least one region of different curvature is created by photoablation of the cornea to permit the eye to accommodate for near objects. This "add" region is preferably located near the center of the optical zone and preferably within Bowman's membrane or the adjacent upper portions of the stroma, which lies directly below Bowman's membrane. Apparatus is disclosed, including a laser means and a beam-shaping means, disposed between the laser means and the surface of the cornea, which imposes a defined ablation profile upon the cornea. The system can also include a feedback control means for measuring the effectiveness of the laser during operation and for controlling the laser. The beam-shaping means can include either an aperture e.g., a beam-shaping stop means alone or in combination with a beam-shaping window, or an mask which is photodecomposable or otherwise graded in its absorptive capacity to present a predefined profile o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.