Background-Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors. Methods-Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression. Results-One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months. Conclusion-Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications. (Br J Ophthalmol 1997;81:136-140)

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BACKGROUND: A change of corneal topography and haze after excimer laser photorefractive keratectomy (PRK) can reduce contrast sensitivity and cause glare. Both glare and contrast sensitivity can be examined in a reproducible manner with one instrument. METHODS: We have used the Berkeley Glare Test to examine 46 eyes of 32 patients before and 1, 3, 6, 9, and 12 months after excimer laser PRK for moderate to high myopia. Multiple regression analysis was used for statistical analysis. RESULTS: High contrast visual acuity showed a statistically significant deterioration during the first 6 months after PRK (p=0.01); 1 year after treatment visual acuity returned to almost pretreatment levels (p=0.2). High- and low contrast visual acuity under glare deteriorated significantly 3 months after PRK and had only risen slightly 1 year later (p≤0.0065). A similar development could be observed for the low contrast visual acuity without glare. CONCLUSION: Although high contrast visual acuity recovers by 1 year after PRK, low contrast visual acuity and glare deteriorate significantly and do not recover, even after 1 year. [J Refract Surg. 1996;12:S267-S268.]

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