Abstract
PURPOSE: To determine visual performance and optical consequences of corneal aberrations following (PRK) for hyperopia.
METHOD: 10 subjects underwent PRK to correct between +2D and +7D of hyperopia using Summit Technology LJV200™ excimcr laser. Refractive error was assessed using retinoscopy and standard subjective tests. Contrast sensitivity (CS) function for ? spatial frequencies (1.5 to 20 cpd). high (98%) and low (6.3%) contrast visual acuities were measured both for the natural and dilated (1% tropicamide) pupil using the Mentor B-VAT™ II-SG Video Acuity Tester. Corneal aberrations (spherical aberration (SA) and coma), for 5.5 mm diameter pupils, were estimated from topography data (measured with ihe TMS-1™, Computed Anatomy, NY) assuming a uni-index, single surface cornea.
RESULTS: 1. Before PRK mean refraction was +4.7D (±l.6), I month following PRK mean sphere was -1.9D (±0.9) and by 6 months +0.9D (±1.7). 2. Best corrected high contrast visual acuity was stili reduced 6 months after PRK for both dilated and undilated pupils. 3. Best corrected low contrast visual acuity was reduced immediately following PRK, but achieved preoperative levels by 6 months (dilated and undilated). 4. Significant changes in CS were found for 3,6, 12 and 20 cpd (pCONCLUSIONS: PRK for hyperopia can adversely affect CS for spatial frequencies of 6 and 12 cpd, and high and low contrast letter acuity. The primary corneal aberrations, SA and coma, were significantly altered following PRK. These results are similar lo those following PRK for myopia, with the exception of the direction of change in SA.
METHOD: 10 subjects underwent PRK to correct between +2D and +7D of hyperopia using Summit Technology LJV200™ excimcr laser. Refractive error was assessed using retinoscopy and standard subjective tests. Contrast sensitivity (CS) function for ? spatial frequencies (1.5 to 20 cpd). high (98%) and low (6.3%) contrast visual acuities were measured both for the natural and dilated (1% tropicamide) pupil using the Mentor B-VAT™ II-SG Video Acuity Tester. Corneal aberrations (spherical aberration (SA) and coma), for 5.5 mm diameter pupils, were estimated from topography data (measured with ihe TMS-1™, Computed Anatomy, NY) assuming a uni-index, single surface cornea.
RESULTS: 1. Before PRK mean refraction was +4.7D (±l.6), I month following PRK mean sphere was -1.9D (±0.9) and by 6 months +0.9D (±1.7). 2. Best corrected high contrast visual acuity was stili reduced 6 months after PRK for both dilated and undilated pupils. 3. Best corrected low contrast visual acuity was reduced immediately following PRK, but achieved preoperative levels by 6 months (dilated and undilated). 4. Significant changes in CS were found for 3,6, 12 and 20 cpd (pCONCLUSIONS: PRK for hyperopia can adversely affect CS for spatial frequencies of 6 and 12 cpd, and high and low contrast letter acuity. The primary corneal aberrations, SA and coma, were significantly altered following PRK. These results are similar lo those following PRK for myopia, with the exception of the direction of change in SA.
| Original language | English |
|---|---|
| Pages (from-to) | S531 |
| Journal | Investigative Ophthalmology and Visual Science |
| Volume | 38 |
| Issue number | 4 |
| Publication status | Published - 1997 |
ASJC Scopus subject areas
- Ophthalmology
- Sensory Systems
- Cellular and Molecular Neuroscience