Schirmer test values and the outcome of photorefractive keratectomy

Abstract

Purpose: To evaluate whether relative tear deficiency, indicated by low standardized Schirmer test values, influences the outcome of photorefractive keratectomy (PRK).Setting: Department of Ophthalmology, University of Helsinki, Finland.Methods: Sixty-two patients were pair-matched by age and attempted myopic correction. They were divided into two groups: Group 1 (n = 31) comprised patients with standardized, eye-closed Schirmer test values of ≤ 6 mm/5 min; Group 2 (n = 31), patients with Schirmer test values of ≥10 mm/5 min. None of the eyes showed clinical signs of dry eye on slitlamp examination. Follow-up was 12 months.Results: At 1 year, the visual acuity was 0.5 or better in 68.4% of Group 1 eyes and in 78.9% of Group 2 eyes. In Groups 1 and 2, 55.6% of eyes and 52.6%, respectively, were within 0.50 diopter (D) of attempted correction and 83.3% and 89.5%, respectively, were within 1.00 D. At 6 months, the mean overcorrection was +1.32 ± 1.13 D in Group 1 and +0.77 ± 0.57 D in Group 2 and at 1 year, +0.96 ± 1.13 D and +0.58 ± 0.37 D, respectively. There was no difference between the two groups in visual acuity and obtained refractive correction or haze score at any postoperative examination. The minor tendency toward overcorrection in Group 1 could not be confirmed statistically.Conclusion: Subdinical tear deficiency indicated by low Schirmer test values did not influence the PRK outcome in patients matched by age and magnitude of refractive correction.