Impact of femtosecond laser-assisted in situ keratomileusis on retinal ganglion cell function

Abstract

Purpose: To analyse the effect of femtosecond laser-assisted in situ keratomileusis (FS-LASIK) on the electrical response of retinal ganglion cells using pattern electroretinography (pERG). Methods: This was a longitudinal, prospective, observational pilot study. We included consecutive myopic patients who underwent FS-LASIK to correct up to 6dioptres of myopia and up to 2dioptres of astigmatism. Patients with excessive blinking or tearing and those with Snellen uncorrected visual acuity less than 0.9 dec on postop day 1 were excluded. Diopsys NOVA® (Diopsys Inc., NJ) pERG records, using high- and low-contrast patterns, were obtained 16 h and 1month after FS-LASIK was performed. Magnitude (μV), Magnitude D (μV), Magnitude D/Magnitude ratio and signal-to-noise ratio (dB) were analysed. Wilcoxon test for nonparametric paired data was employed. Results: pERG data from 24 eyes were analysed from 24 patients who underwent FS-LASIK. Mean age was 35.79±9.86 years. Mean preoperative refraction was −2.69±7.6D (spherical) and −0.38±0.40D (cylinder). Mean surgical time was 56.88±7.6s. No statistically significant differences were obtained for any of the studied parameters when comparing 16h with 1month after FS-LASIK, with the exception of Magnitude with low contrast, which increased from 1.21±0.2 to 1.39±0.29µV at 16 h and 1month postoperatively, respectively (p=0.03). Conclusions: FS-LASIK seems to induce a mild and transitory defect in retinal ganglion cell function. Only a mild decrease was detected in the magnitude value for low-contrast stimuli when pERG was performed 16h postoperatively, and it returned to normal 1 month after surgery.