Corneal epithelium, visual acuity and laser refractive keratectomy

Gabriel Simon, Jean Marie Parel, Gerard Kervick, Pascal Rol, Khalil Hanna, Keith Thompson

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

Photorefractive keratectomy (PRK) using an argon fluoride excimer laser for photoablation of the cornea shows potential for the precise correction of refractive errors in patients. Usually, the epithelium is mechanically removed, and Bowman's layer and stromal tissue are photoablated to precomputed depths and shapes that are based on known ablation rates for these tissues. After four day's time, the epithelium has regrown. Assuming the epithelium to be preoperatively uniform in thickness across the central optical zone, and assuming that it regrows to the same thickness, a theoretical precision of ±0.05 diopters is achievable with PRK. Keratometric measurements of the epithelium and of Bowman's layer were made at the 2.0 and 3.6mm optical zones on 10 fresh cadaver eyes (<21 hours postmortem). In the eyes studied, the epithelium thickness was found to vary across the central optical zone, accounting for the measured refractive differences of 0.5 to 1.8 diopters. Bowman's layer was found to be more prolated than the epithelial surface (ratios: 1.005 compared to 1.033). In addition, the surface of Bowman's layer had a larger degree of astigmatism.

Original languageEnglish (US)
Pages (from-to)154-156
Number of pages3
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume1423
StatePublished - Jan 1 1991
EventProceedings of Ophthalmic Technologies - Los Angeles, CA, USA
Duration: Jan 21 1991Jan 22 1991

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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