Post‑laser in‑situ keratomileuses effects on visual field in myopia and myopic astigmatism

Background The suction used during the laser insitu keratomileusis (LASIK) procedure necessary for cutting of the cornea by an oscillating blade induces an increase of intraocular pressure (IOP) to approximately 60 mm Hg or even more. This acute increase in IOP during LASIK may endanger the blood flow within the retinal vessels and induce visual field (VF) depression. Purpose To identify the effect of LASIK on the visual field parameters. Settings Prospective interventional case series study performed in ELNOOR ophthalmology center. From October 2015 to October 2016. Methods Prospective interventional case series study including patients with myopia and myopic astigmatism who were deemed candidates for LASIK correction. All recruited patients underwent visual field examination immediately before,1 week and 3 months post LASIK using Humphrey 750 Visual Field Analyzer (Zeiss Humphrey Systems, San Leandro, CA, USA), with a white-on-white Swedish Interactive Threshold (SITA). LASIK procedure was done using Allegretto device (wave light EX500, ALCON, Fort Worth, TX, USA) and Moria microkeratome (MM2). Results 60 eyes of 30 patients were included in our study. Mean age was 28 + 5.6 years (range20-41), mean spherical equivalent (S.E) was -6.1 + 3.2 D (Range -1.4 to -15.1D), mean axial length was 23.5 + 1.5mm (Range 21-26.3mm). Humphrey global indexes included MD and PSD. The MD index estimates the uniform part of VF deviation, while the PSD index estimates the non-uniform part of VF deviation, reflecting the amount of localized depression of the VF. We found that (MD) shows slight decrease 1-week postoperative which is statistically significant, then improved 3 months postoperative with no statistical significant difference between preoperative and 3 months postoperative values. As regards PSD we found that there is no statistical difference between preoperative,1 week and 3 months postoperative. Conclusion The surgery of LASIK is safe and efficient, but surgeons should choose effective and safe suction mode, shorten the suction time and exclude potential retinopathy and preexisting glaucoma before surgery to improve the safety and efficacy. We found that LASIK procedure has no significant effect on visual field parameters, except for diffuse depression that occurs in the first week postoperative.