Changes in stereopsis after photorefractive keratectomy

PURPOSE: To evaluate the effects of photorefractive keratectomy (PRK) on the stereopsis of myopic and hyperopic patients. SETTING: Farabi Eye Hospital, Tehran, Iran. DESIGN: Prospective case series. METHODS: This study included patients having PRK to achieve emmetropia. The patients were divided into the following 3 groups: low myopia (<-6.0 diopters [D]), high myopia (>-6.0 D), and hyperopia (<+4.0 D). Near stereoacuity was measured using the Randot test under photopic conditions (with corrective glasses) at 40 cm preoperatively (with corrective glasses) and 1, 3, and 12 months postoperatively. Repeated-measure analysis of variance was used to assess changes in stereopsis over time in the 3 groups. RESULTS: Each group comprised 60 patients. The mean preoperative stereoacuity was 121.16 seconds of arc (arcsec) +/- 149.92 (SD), improving to 83.66 +/- 75.84 arcsec 1 month postoperatively and 80.66 +/- 64.31 arcsec at 3 months (both P<.001). It remained unchanged (83.33 +/- 75.01 arcsec) at 12 months (P=.610). Patients with high myopia had the greatest improvement in stereopsis after PRK compared with low myopic and hyperopic patients (P<.001). The improvement in stereoacuity was significantly higher in the severe anisometropic group; the lowest improvement was in the group without anisometropia. CONCLUSION: Photorefractive keratectomy could result in an improvement in stereopsis. Patients with high myopia benefitted most from PRK in terms of improvement in stereopsis. (C) 2016 ASCRS and ESCRS