Comparison of mechanical debridement and trans-epithelial myopic photorefractive keratectomy: A contralateral eye study.

Purpose: To compare clinical outcomes between mechanical debridement photorefractive keratectomy (m-PRK) and trans-epithelial photorefractive keratectomy (t-PRK) in myopic patients.

Methods: Eighty eyes of 40 myopic patients with age between 18 and 55 years were included in this study. In each patient, one eye was randomly assigned for t-PRK, using the Amaris laser's ORK-CAM software and the other eye for m-PRK, using a spatula. Stromal ablation was done by Schwind Amaris 750S. Uncorrected and best corrected visual acuity (BCVA), refractive outcomes, epithelial healing, pain, and discomfort were compared between the groups on day 1, 3, 7 and month 1, 3, and 6.

Results: Preoperative spherical equivalent (SE) were -3.97 ± 2.08 diopter (D) and -3.98 ± 2.06 D in m-PRK and t-PRK eyes, respectively ( = 0.981). Operation time was significantly shorter in the t-PRK group than m-PRK ( < 0.001). Postoperative pain was experienced significantly higher in the t-PRK group measured by 11-point numeric scale of pain questionnaire on the first postoperative day ( < 0.001). Photophobia, tearing, and vision fluctuation were also significantly higher in the t-PRK group postoperatively. However epithelial defect size and re-epithelialization time were lower in the t-PRK group ( = 0.012 and  < 0.001, respectively). Postoperative parameters including SE, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and contrast acuity did not show any significant difference between the two groups during all intervals.

Conclusions: Although epithelial defect size and epithelial healing time were lower in t-PRK, postoperative pain, photophobia, and vision fluctuation were significantly less in the m-PRK group in the first postoperative days. There was no statistically significant difference between the groups after one week, and both mechanical and trans-epithelial techniques were shown to be safe and effective.