Prk On Lasik Flaps Vs. Primary Prk In Myopic Eyes: A Propensity Score-Matched Comparison Of Outcomes And Safety

Published 2026 - 44th Congress of the ESCRS

Reference: FP27.04 | Type: Free paper | DOI: 10.82333/xkjm-mj53

Authors: Dr Adir Sommer* ¹ , Dr Dror Ben Ephraim Noyman ¹ , Dr Waseem Nasser ¹ , Dr Margarita Safir ² , Avinoam Shye ¹ , Mr Tzahi Sela ³ , Mr Gur Munzer ³ , A/Prof. Igor Kaiserman ⁴ , A/Prof. Michael Mimouni ¹

¹Rambam Health Care Campus,Haifa,Israel, ²Rabin Medical Center,Petah Tikva,Israel, ³Care-Vision Laser Center,Tel-Aviv,Israel, ⁴Barzilai Medical Center,Ashkelon,Israel

Purpose

To compare the predictability, visual, and refractive outcomes of Photorefractive Keratectomy (PRK) performed on a pre-existing LASIK flap versus primary PRK in myopic eyes using a propensity score-matched design.

Setting

Retrospective Study, Care-Vision Laser Center, Tel Aviv, Israel

Methods

This retrospective comparative study included 523 myopic eyes of 425 patients (mean age 34.92±9.42). Propensity score matching (1:2 ratio, caliper=0.05) was used to balance baseline characteristics between the PRK on flap (n=178) and primary PRK (n=345) groups, matching on age, sex, eye laterality, pachymetry, keratometry, subjective refraction, uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA). Multivariate general linear model adjusted for potential confounders, and multivariate logistic regression assessed the association between treatment type and target achievement.

Results

Mean follow-up was 139.0±54.2 days for primary PRK and 151.8±79.1 days for the PRK on flap group (p=0.15). No significant differences were observed in postoperative UCVA (0.93±0.19 vs. 0.94±0.18, p=0.581), BCVA (0.98±0.12 for both groups, p=0.792), safety index (1.02±0.13 vs. 1.01±0.11, p=0.493), or efficacy index (0.97±0.20 vs. 0.97±0.17, p=0.948). While both groups neared emmetropia, the flap group showed a significant hyperopic tendency. These findings persisted after multivariate adjustment for SEQ (−0.02±0.51 vs. −0.15±0.51D, p=0.016) and sphere (+0.07±0.56 vs. −0.05±0.49D, p=0.022). Refractive predictability was comparable, with 92.1% vs. 92.9% within ±1.0D (p=0.667). Multivariate logistic regression further confirmed these findings.

Conclusions

PRK performed on pre-existing LASIK flaps achieves visual acuity, safety, and efficacy outcomes that are comparable to those of primary PRK on virgin corneas. Both groups attained postoperative refraction near emmetropia with equivalent predictability. A mild tendency toward a more hyperopic refractive outcome was observed in the PRK on flap group, though the final SEQ remained close to plano. These findings suggest that PRK on LASIK flaps is a safe and effective treatment option, and that larger, prospective studies are warranted to determine whether minor nomogram adjustments should be considered to account for this slight hyperopic tendency in eyes with pre-existing flaps.