Ashok Kumar P
BACKGROUND
To evaluate visual outcomes following LASIK and Photorefractive Keratectomy (PRK) in low-to-moderate myopia and/or myopic astigmatism in age and refractive error matched eyes.
MATERIALS AND METHODS
Of a total 30 patients aged ≥21 years, 20 (40 eyes) underwent LASIK and 10 (20 eyes) underwent PRK for low-to-moderate myopia or myopic astigmatism. LASIK was performed with the Alcon wave light 500 and PRK with the alcohol application for epithelial removal. All ablations were performed using the same excimer laser system. One surgeon operated all patients by using an excimer laser (Alcon wave light 500 system). Age and refractive error matched patients were divided in two groups. Preoperative and one year postoperative uncorrected visual acuity, best corrected visual acuity and manifest refractions were recorded to compare the outcomes of both the procedures. Outcome measures to assess the patient comfort levels in both groups include postoperative pain and quality of vision. Other outcome measures to assess the wound healing includes intraoperative complications, corneal haze and corneal reepithelialisation.
RESULTS
Sixty eyes of 30 patients were found matched regarding age and refractive error. In PRK group, among 10 patients, 5 (50%) were males and 5 (50%) were females, whereas in Lasik group, males were 12 (60%) and 8 (40%) were female patients. Mean preoperative MRSE was -4.06 ± 1.00 Dioptres (D) for LASIK versus -4.50 ± 1.25 D for PRK. Complete flap healing was achieved by postoperative day 4 in 86.9% of LASIK eyes versus complete reepithelialisation in 92.4% of PRK eyes. Using Fisher exact test, a significantly higher percentage of LASIK eyes compared to PRK eyes achieved 20/15 or better at 1 month (35.8% vs. 17.8%, P=0.031), 3 months (69.3% vs. 49.3%, P=0.004), 6 months (79.1% vs. 59.9%, P<0.001) and 12 months (85.9% vs. 61.9%, P=0.002). A change in MRSE >0.50 D occurred in 12.4% of LASIK eyes within the 3- and 12-month interval versus 25.7% of PRK eyes (P=0.04). Patients in both groups were happy regarding their visual outcome.
CONCLUSION
LASIK showed superior refractive efficacy and stability for low-to-moderate myopia with RBT (residual bed thickness) >320 microns. PRK shows better results in thinner corneas (RBT 280-320 microns). Both treatments were safe and comparable except in terms of pain and haze formation in selective PRK cases.
