PRELIMINARY ANALYSIS OF 8,624 EYES UNDERGOING TRANSEPITHELIAL PHOTOREFRACTIVE KERATECTOMY IN TAIWAN DURING 2017–2023

    To describe the demographic characteristics, refractive profiles, and surgical parameters of patients undergoing transepithelial photorefractive keratectomy (transPRK) in Taiwan from 2017 to 2023, and to report the rates of postoperative haze and secondary enhancement.

    Single center (WishVision), multi-sites, retrospective cohort study.

    This retrospective, multicenter study analyzed 8,624 eyes that underwent primary transPRK between 2017 and 2023. Baseline demographic variables included age, sex, and laterality. Preoperative parameters included spherical equivalent (SE), sphere, and astigmatism refraction. Surgical variables comprised optical zone (OZ), transition zone (TZ), ablation depth, and decentration. Postoperative metrics included secondary enhancement rate and the incidence of corneal haze. Summary statistics were reported as mean ± standard deviation and range for continuous variables, and as counts or percentages for categorical variables.

    The mean age at surgery was  31.2±5.4  years (range 18-61). The overall distribution between right and left eyes was approximately equal ( 50.01% vs  49.99%). The mean preoperative spherical equivalent was  -5.29±1.98  D with mean cylinder –0.926 ± 0.75D. The mean optical zone and full ablation zone (including transition zone) diameters were  6.91±3.6  mm and 8.45±0.32  mm, respectively. Average ablation depth was 139.36± 27.27µm. The rate of secondary enhancement was  1.31%, and clinically significant corneal haze (≥ grade 1) occurred in  1.15 % of eyes. 70% of haze occurred within the first month post-operation.

    In the multivariable Firth logistic regression model controlling for age and sex (n = 8,470), longer ablation time was significantly associated with an increased risk of postoperative corneal haze (β = 0.0336 ± 0.0111, p = 0.0026). None of the other predictors, including central corneal thickness, epithelial thickness, use of autologous serum, age, or sex, showed significant associations with haze (all p > 0.2). The model demonstrated an overall likelihood-ratio χ² = 13.98 (df = 6, p = 0.0298), indicating that the included covariates jointly contributed to explaining the variation in haze occurrence despite the event being rare (~1%).

    This large-scale, real-world dataset provides the first comprehensive demographic and surgical profile of transPRK in Taiwan. The findings suggest transPRK achieves stable and predictable refractive correction with a low enhancement rate and minimal haze formation. These data may provide a reference for future regional or international comparisons.