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RESEARCH PRODUCT

Changes in the visual field following laser in situ keratomileusis for myopia

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Purpose:  To assess the changes of the visual field (VF) caused by transient intraocular pressure (IOP) peaks during laser in situ keratomileusis (LASIK) surgery for myopia using automated perimetry. Methods:  This prospective study involved 94 eyes of 94 patients who underwent a conventional LASIK procedure. A complete eye examination was carried out in which the IOP measurement, and Humphrey 24-2 SITA standard VF were tested prior to LASIK and 6 and 12 months after LASIK. Patients were divided into two subgroups according to their refractive error. VF global indices, Glaucoma Hemifield Test and the number of depressed points deviating at p < 5%, p < 2%, p < 1% and p < 0.5% on the Pattern Deviation probability maps were compared using the analysis of variance. Results:  In the low myopia group, there were no significant differences in the analysed variables, except a slight decrease in mean deviation (MD) when comparing results prior to and 6 months following LASIK (p = 0.036; anova) that returned to baseline values at 12 months after surgery. In the moderate and high myopia group, there were no statistically significant differences in any of the variables analysed. No significant correlation was found between the transitory reduction in MD and any of the variables studied. Conclusions:  In patients with low myopia, the VF undergoes a transitory increase in diffuse defects 6 months after surgery, with spontaneous recovery at 12 months after LASIK procedure. Possible explanations for these findings are discussed.