Simultaneous photorefractive keratectomy and accelerated collagen cross-linking in high-risk refractive surgery (Tehran protocol): 3-year outcomes

Purpose: To evaluate safety and efficacy of performing simultaneous photorefractive keratectomy (PRK) and collagen cross-linking (CXL) in myopic patients with preoperative risk factors for developing keratectasia. Methods: Seventeen eyes of 15 patients with at least one of the following risk factors were recruited: central keratometry (Kmax) between 48 and 50, difference between inferior, superior corneal power (I�S value) between 1.4 and 1.9 and corneal thickness between 450 and 480 µm. Upon final stage of standard PRK, 0.02 mitomycin was applied for 30�50 s, and then, accelerated CXL was performed for 5 min. Pre- and postoperative Oculus Pentacam® imaging for keratometry values, measurement of uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were done for all patients. Results: Mean follow-up time was 32.08 ± 7.79 months (range 25�49 months). Mean age of patients was 28.78 ± 3.80 years. Mean postoperative spherical equivalent was + 0.19 ± 0.42 (� 0.5 to + 1.0 D). Mean UDVA and CDVA improved from 0.9062 ± 0.485 log MAR and 0.0148 ± 0.043 log MAR to 0.0173 ± 0.040 log MAR and 0.0057 ± 0.023 log MAR, respectively (P = 0.011, P = 0.735). Mild degree of early postoperative stromal haze was seen which did not persist more than 6 months. There was no late stromal haze, corneal ectasia or other major postoperative complication in the follow-up period. Conclusion: Combined PRK and accelerated CXL is an efficient and safe procedure for high-risk refractive surgery candidates, with no increased risk of persistent corneal haze. © 2020, Springer Nature B.V