Comparative study of transepithelial versus alcohol-assisted photorefractive keratectomy

Abstract

Aim The aim of this study was to compare the clinical, refractive, and visual outcome of transepithelial photorefractive keratectomy (T-PRK) to the alcohol-assisted photorefractive keratectomy (AA-PRK). Patients and methods This is a prospective randomized controlled trial that included 60 myopic patients (120 eyes). They were randomized into two groups, 60 eyes each: group I (AA-PRK) and group II (T-PRK). The operation was performed in both groups by the same Excimer laser machine (EX 500 Excimer laser WaveLight). In the alcohol-assisted group, the corneal epithelium was removed by 20% ethyl alcohol followed by Excimer laser to correct the amount of ametropia. In the T-PRK group, the Streamlight PRK software (WaveLight EX 500) was used, which incorporated Excimer laser stromal ablation and epithelial removal in a single step. After completion of each procedure in both groups, mitomycin C with a concentration of 0.02% was used for 30 s, followed by copious irrigation with a cold balanced salt solution. A soft bandage contact lens was applied until epithelial healing was complete for 5 days and changed after 48 h. The patients were evaluated postoperatively on the first, third, and fifth day, then after 1 week, 1 month, and 3 months. On the first visit, uncorrected visual acuity (UCVA), epithelial healing, and postoperative pain were evaluated. At 1-week and 1-month follow-up visits, UCVA, best-corrected visual acuity (BCVA), manifest refraction spherical equivalent (MRSE), Schirmer’s I, and tear break-up time (TBUT) tests were evaluated. The corneal haze was evaluated using a slit lamp biomicroscope and subjectively graded. At the 3-month follow-up, UCVA, BCVA, MRSE, Schirmer’s I test, TBUT test, and root mean square (RMS) assessment for total higher-order aberration were evaluated. Results There was an insignificant difference between the studied groups regarding all baseline ophthalmological assessments including UCVA, BCVA, MRSE, central corneal thickness, RMS, TBUT, and Schirmer’s test (P=0.839, 0.057, 0.187, 0.537, 0.219, 0.013, and 0.151, respectively). After 3 months, the median UCVA was the same in both groups (1.0), while the MRSE did not differ significantly between the two groups (P=0.126), with a median (interquartile range) of −0.25 D (−0.75 to 0.25 D) in the AA-PRK group compared to −0.25 D (−0.50 to 0.3125 D) in the T-PRK group. The healing duration was significantly shorter in the T-PRK group (median=3.0 days) than in the AA-PRK group (5.0 days, P<0.001). The median postoperative pain was also significantly higher in the AA-PRK group (4.0) than in the T-PRK group (3.0, P<0.001). The RMS was significantly lower in the T-PRK group (median=0.35) than in the AA-PRK group (median=0.65, P<0.001). The corneal haze did not differ significantly between the two groups after 1 month (P=0.783). After 3 months, the Schirmer’s test was significantly lower in the AA-PRK group (median=18.0 mm) than in the T-PRK group (19.0 mm, P<0.001), while the TBUT test showed no significant difference (P=0.055). Conclusion The T-PRK technique provided a faster visual recovery with a better refractive outcome, faster healing response, less pain score, and less dryness than the AA-PRK.