Visual field changes after laser in situ keratomileusis in myopic eyes

Purpose: To evaluate the effect of acute elevation of intraocular pressure (IOP) during laser in situ keratomileusis (LASIK) on the visual field in myopic eyes. Setting: Istanbul University, Cerrahpassa Medical Faculty, Istanbul, Turkey. Methods: Thirty-seven eyes of 37 patients were included in the study. The LASIK procedure was performed using the Hansatome(R) microkeratome (Bausch & Lomb) and the Summit SVS; Apex Plus(R) 193 nm argon-fluoride excimer laser. Visual field testing was performed twice before LASIK and 1 day and 24 months after LASIK. Seventy-six points, 6 degrees apart, in the central visual field (Central 30-2) were tested for threshold sensitivity (Humphrey). The mean threshold sensitivity of baseline and post-LASIK visual field examinations was calculated in each patient. Seventy-six points of the Central 30-2 test were divided into 21 clusters corresponding to perimetric nerve-fiber bundles derived from Peridata software version 6.2a (Interzaag AG). The mean threshold sensitivity of each cluster and the visual field indices (mean deviation [MD] and corrected pattern standard deviation [CPSD]) in baseline and follow-up visual fields were compared using analysis of variance. Results: The mean age of the 23 men and 14 women was 31.04 years +/-6.55 (SD). The mean spherical equivalent refraction was -4.21+/-1.66 diopters (D) (range -2.25 to -6.75 D). The mean duration of suction was 42.29+/-29.06 seconds. The mean visual field sensitivity at baseline and the 2 follow-up examinations was 25.97+/-2.04 dB, 25.70+/-1.99 dB, and 27.17+/-1.68 dB, respectively (P=.181). There was no difference between preoperative and postoperative visual field clusters except in area 13. In area 13, threshold sensitivity was decreased at 1 day (P=.039) and at the preoperative level at 24 months. The MD of the visual fields was -3.53+/-1.67 dB, -3.61+/-2.91 dB, and -2.61+/-1.66 dB at the preoperative and 2 postoperative examinations, respectively (P=.495). The mean CPSD of the visual fields was 1.76+/-1.24 dB, 1.42+/-0.85 dB, and 1.74+/-0.86 dB, respectively (P=.680). Conclusion: Laser in situ keratomileusis did not cause visual field defects in mild to moderate myopic patients who had no risk factors that might render the optic nerve more vulnerable to damage.