Changes in the multifocal electroretinogram before and after LASIK in eyes with different degrees of myopia

Objective To evaluate the changes in the function of the macular region in patients with different degrees of myopia at different sites on the retina before laser in situ keratomileusis (LASIK) and 3 months after LASIK. Methods Ninety-one patients (169 eyes) with myopia ranging in age from 18-32 years were enrolled from 2012 to 2013 for this prospective controlled study. Patients were divided into 3 groups: 58 eyes, low myopia; 57 eyes, moderate myopia and 54 eyes, high myopia. All patients underwent strict examinations before the surgery was performed. All patients underwent multifocal electroretinogram (mERG) examinations using RETI-SCANK (Roland, Germany) to determine the function of the macular region before and after LASIK. The latencies and the amplitude densities of the P1 and N1 waves were measured at each ring. All exams were performed by the same surgeon. The distinctions among the 3 groups and before and after LASIK were then analyzed using ANOVA and paired t test. Results The study showed that the amplitude densities of the three groups before and after LASIK were the highest at ring one, which decreased rapidly but then increased at the most eccentric ring. The latencies were shortest at ring one, and delayed gradually at the more eccentric rings, and then increased at the farthest eccentricity. The tests showed that there were no statistically significant differences in amplitude densities or latencies between any group before or after LASIK. Conclusion LASIK surgery has no influence on the function of the macular region in myopic eyes. Key words: Electroretinography; Myopia; Keratomileusis, laser in situ; Macula lutea; Retinal function