PRK Enhancement for Residual Refractive Error After Primary PRK: A Retrospective Study

Abstract

Introduction The efficacy and safety of photorefractive keratectomy (PRK) has been well documented, but outcomes of PRK enhancement following PRK remain understudied. This study aimed to evaluate the safety, efficacy, and predictability of PRK enhancement in patients with residual refractive error after primary PRK and compare these results to prior studies as well as Food and Drug Administration (FDA) safety and efficacy clinical endpoints. Methods This non-randomized, retrospective chart analysis included eyes with a history of PRK that underwent PRK enhancement at a single center. Post-enhancement data were documented at 3-month and 1-year visits. Patient characteristics between the study group and a control group who underwent primary PRK only were compared. Safety and efficacy measures included change in uncorrected distance visual acuity (UDVA), change in corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), amount of induced astigmatism, and presence of serious adverse events. Results A total of 188 eyes from 141 patients were included. When compared to the control group, women underwent PRK enhancement at a higher rate than men ( P = 0.004). The group undergoing PRK enhancement had a higher sphere ( P = 0.013) and spherical equivalent ( P = 0.004) than the control group at the time of primary PRK. MRSE was reduced to − 0.97 ± 0.72 D (− 2.25 to + 2.13 D) from pre-enhancement values of − 0.98 ± 0.66 D (− 2.75 to + 1.75 D) and stable over 12-month visits with 86% and 98% of eyes within ± 0.50 D and ± 1.00 D of target, respectively. UDVA of 20/20 or better was achieved in 75% of eyes. The UDVA of 75% of eyes remained the same or improved by 1 or more Snellen lines compared with pre-enhancement CDVA. Conclusion Our results demonstrate that, when compared with previous studies, modern PRK enhancement after PRK has improved visual acuity and refractive outcomes. Though PRK enhancement is not an FDA approved procedure, we show that it meets or exceeds the FDA criteria for the correction of refractive error.

Refractive Corneal Lenticule Extraction on Previous Photorefractive Keratectomy, with Optical Coherence Tomography Study

“…The correction of refractive errors after PRK can be addressed by several techniques. Repeat PRK has the disadvantage of pain, slow recovery, possible induction of haze [8].…”

“…The correction of refractive errors after PRK can be addressed by several techniques. Repeat PRK has the disadvantage of pain, slow recovery, possible induction of haze [8]. Microkeratome LASIK is rarely performed because of the reduced accuracy of the thickness of the flap in eyes in which stromal thickness is already affected by previous surgery [9].…”

Enhancement-Optionen nach Linsen- und refraktiver Hornhautchirurgie

“…Eine rezente Studie konnte sowohl sehr gute refraktive Ergebnisse als auch ein hohes Maß an Sicherheit bei einer PRK als Enhancement bestätigen 19 .…”

Letter to the Editor: Laser Enhancements After Surface Ablation

“…We read with interest the article by Moshirfar et al [ 1 ] about photorefractive keratectomy (PRK) enhancements following primary PRK. They show good results with the technique, which supports the well-established practice worldwide of retreating residual refractive errors following PRK with a repeat surface ablation procedure.…”

“…In our study, we focused our discussion on the lack of toxicity with the use of mitomycin C (MMC) in these retreatments. Moshirfar et al [ 1 ] also report using MMC in their series of eyes when the ablation depth was deeper than 65 microns. Similar to those reported by Moshirfar et al, our safety and efficacy indices after enhancement (1.01 and 0.96, respectively) supported, already in 2010, the use of a surface ablation technique for enhancements after previous surface ablation procedures.…”