Intraocular Pressure Changes after Laser-Assisted In-Situ Keratomileusis versus Photorefractive Keratectomy in Myopic Eyes

Objective: The aim was to compare intraocular pressure (IOP) changes after laser-assisted in situ keratomileusis (LASIK) versus photorefractive keratectomy (PRK) in myopic eyes. Background: IOP measurement is necessary for diagnosing glaucoma. LASIK and PRK are used for the correction of myopia. IOP is underestimated after LASIK and PRK. It is very important to evaluate IOP changes after LASIK and PRK especially in myopic patients, as myopia is a risk factor for primary open-angle glaucoma. Patients and methods: A total of 50 patients diagnosed clinically to have myopia were selected. Their ages ranged from 18 to 48 years. A total of 50 eyes were operated using LASIK and 50 eyes were operated using PRK. Patients were subjected to corneal topography by pentacam and IOP measurement by Goldmann applanation tonometer (GAT), preoperatively and postoperatively at the end of the first week, the first month, and the third month. Results: The mean IOP in LASIK and PRK groups, which was preoperatively 15.86 ± 1.99 and 15.62 ± 2.12 mmHg, respectively, decreased postoperatively to 12.98 ± 1.83 and 12.98 ± 2.03 mmHg, respectively. There is a statistically nonsignificant difference between LASIK and PRK, postoperatively (P = 0.164), whereas there was a statistically highly significant difference between preoperative and postoperative IOP in both LASIK and PRK groups (P = 0.000). Conclusion: IOP is underestimated after laser correction. IOP decrease can be dramatic in highly myopic corrections. Preoperative IOP is the single strongest predictor of postoperative IOP change, with eyes with higher preoperative IOP having greater IOP decrease. LASIK correction will lower IOP by ∼1 mmHg because of the effect of the lamellar flap.