Author/Authors :
Zarei-Ghanavati Siamak Eye Research Center - Mashhad University of Medical Sciences - Mashhad, Iran , Abrishami Mojtaba Eye Research Center - Mashhad University of Medical Sciences - Mashhad, Iran , Heravian Shandiz Javad Refractive Errors Research Center - School of Paramedical Sciences - Mashhad University of Medical Sciences - Mashhad, Iran , Karimpour Maliheh Refractive Errors Research Center - School of Paramedical Sciences - Mashhad University of Medical Sciences - Mashhad, Iran
Abstract :
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
(P ¼ 0.981). Operation time was significantly shorter in the t-PRK group than m-PRK (P < 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 (P < 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 (P ¼ 0.012 and P < 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.
Keywords :
Trans-epithelial PRK , Mechanical PRK , Epithelial debridement , Photorefractive keratectomy
