Re-Evaluate Your Refractive Surgery Screening

Epithelial thickness mapping adds value for eligibility determinations and surgical planning. Cheryl Guttman Krader reports

OCT-derived epithelial mapping appears promising as an adjunctive screening tool for corneal refractive surgery decision making, new research suggests.

The research, presented at the 2021 ARVO Annual Meeting, included data for 100 consecutive patients who attended the Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA, for corneal refractive surgery. It showed when two masked reviewers had access to epithelial mapping in addition to Scheimpflug tomography, clinical data, and patient history, determinations on candidacy and surgery choice changed in a substantial percentage of cases.

J Bradley Randleman MD, Professor of Ophthalmology, Cleveland Clinic Cole Eye Institute, told EuroTimes, “We feel there are significant advantages to using epithelial mapping for patient evaluations, particularly for borderline cases. Using this technology, more patients have been ruled in for surgery than excluded.

“However, it is important to point out that epithelial mapping is not used in isolation. Rather, the findings correlated with curvature and elevation patterns from Scheimpflug tomography, and we also consider patient age, corneal thickness, and refractive error,” he continued.

Dr Randleman said he began using OCT-derived epithelial mapping for refractive surgery patient evaluations in 2014. He credited work done by Dan Reinstein MD on epithelial remodeling done with high-frequency digital ultrasound and David Huang MD for developing OCT epithelial thickness mapping and demonstrating differences between keratoconic and normal corneas.

“After evaluating epithelial mapping with OCT as a screening tool in our own practice, we began using it routinely,” he said.

A normal cornea tends to have a gradient of epithelial thickening with slightly greater thickness inferiorly. Therefore, when one sees mild inferior steepening on curvature, it is reassuring to find with thicker epithelium inferiorly. However, seeing central or paracentral epithelial thinning raises concern. This is especially true if there is focal thinning with surrounding epithelial hypertrophy, he explained.

In the retrospective study, after the reviewers evaluated the epithelial maps, their decisions on surgery candidacy changed for 17% of patients. In 59% of the latter cases, patients previously screened out were deemed eligible for surgery. Among patients who remained eligible for surgery after the epithelial maps reviews, the decision on surgery of choice changed in 21% of cases.

In the subgroup of cases for which surgical decisions were unchanged after reviewing the epithelial maps, the information still had an impact, as it increased the reviewers’ confidence in their decision in 49% of cases and decreased their confidence in 18% of cases, Dr Randleman noted.