Incomplete Corneal Epithelialization at the One-Week Visit After PRK: Incidence and the Dominance of Examination Timing

PURPOSE: To determine the incidence and independent predictors of incomplete corneal epithelialization at the one-week visit after photorefractive keratectomy (PRK), accounting for correlation between fellow eyes. SETTING: A high-volume refractive-surgery network, Israel. DESIGN: Retrospective registry-based cohort study. METHODS: 37,982 eyes of 18,991 patients who underwent bilateral same-session PRK (January 2013-June 2024), examined on postoperative days 5-9. The outcome was modeled by generalized estimating equations (logistic; exchangeable correlation, robust standard errors) clustered on patient. Visit day and optical zone were also modeled categorically; surgeon was examined as a covariate and a clustering level. RESULTS: Incomplete epithelialization occurred in 1,804 of 37,982 eyes (4.8%; 95% CI, 4.5-5.0). Rates were 17.2%, 5.5%, 4.3%, 4.1% and 3.3% on days 5 through 9. Day 5 carried almost five-fold the odds of day 7 (OR 4.78; 95% CI, 3.73-6.13) and day 6 remained elevated (OR 1.30; P=0.003); days 8-9 did not differ significantly from day 7. No surgical parameter was consistently associated with the outcome. Preoperative spherical equivalent, null in the primary model, was associated once surgeon was accounted for (OR 0.93 per +1 D; P=0.019). An affected eye predicted an affected fellow eye in 73.3% of affected eyes, against 1.33% of healed eyes. CONCLUSIONS: At one week, incomplete epithelialization is uncommon, is concentrated at day 5, and resolves gradually to a stable baseline by day 7, consistent with assessment timing rather than a distinct entity, and supporting a day-7 review default. It is predominantly patient-level, and no surgical parameter was consistently associated with it.