Interexpert agreement on epithelial thickness mapping for refractive surgery screening: variability highlights need for standardization.

PURPOSE: To evaluate interexpert agreement on epithelial thickness map interpretation and its influence on eligibility decisions for keratorefractive surgery candidates.

SETTING

Multicenter international collaboration involving 4 experienced refractive surgeons.

DESIGN

Retrospective, masked case review study.

METHODS

A total of 103 cases were retrospectively evaluated, including patients with normal (n = 44), borderline (n = 44), and keratoconic (n = 15) corneal tomography, as defined by the Belin-Ambrosio display (BAD). 4 independent experts (M.D., J.L.A.d.B., A.S., and N.L.) first assessed surgical eligibility based on Scheimpflug tomography and subsequently re-evaluated the same cases with the addition of anterior segment optical coherence tomography-based epithelial thickness maps. To ensure comparability, a standardized questionnaire with 9 predefined epithelial thickness characteristics was used. Interrater agreement was quantified with Fleiss κ, and the relative impact of each imaging modality on decision-making was ranked.

RESULTS

Incorporating epithelial mapping changed the eligibility decision in 19% (77/412) of cases. Specifically, 9% (16/176) of normal, 20% (35/176) of borderline, and 3% (2/60) of keratoconic cases were reclassified as eligible, while 2% (3/176), 6% (10/176), and 3% (2/60), respectively, were deemed ineligible. Interrater agreement on eligibility was moderate before (κ = 0.46) and after (κ = 0.43) adding epithelial maps but remained poor in borderline cases (κ = 0.14 and 0.12, respectively). Agreement on epithelial profile features ranged from poor to fair (κ = -0.78 to 0.35). Corneal topography and BAD were ranked as most influential, followed by epithelial mapping.

CONCLUSIONS

Epithelial mapping frequently shifted decisions toward eligibility. However, poor interexpert agreement highlights the need for standardized, safety-oriented interpretation to ensure consistent ectasia risk assessment before refractive surgery.