Utility of Stromal Thickness Maps in Surgical Decision Making for Corneal Crosslinking in Patients With Keratoconus

To assess the effect of surgical decision making on the type of corneal crosslinking (CXL) protocol in eyes with keratoconus (KC) based on stromal thickness maps and thinnest corneal pachymetry (TCP).

A prospective, nonrandomized cohort study was performed between January 2022 and January 2023. Patients were allocated to Epi-off or transepithelial CXL (TE-CXL) procedures depending on the TCP value using Scheimpflug. TCP ≥450 μm was used to designate patient's eye to the Epi-off CXL procedure and TCP <450 μm to TE-CXL. On the same day, a combined Placido and Anterior Segment OCT evaluation was performed to assess epithelial thickness (ET) and minimum stromal thickness (MinST). The type of surgery was then finally selected: Epi-off CXL was indicated when MinST ≥400 μm, whereas TE-CXL procedure was indicated when MinST <400 μm. We assessed the percentage of cases in which MinST data changed the surgical decision (Utility).

The study included 245 eyes, MinST was 407.26 ± 50.92 (range 223-497). Stromal thickness maps assessed before surgery altered the surgeon's decision making in 5.30% (13 out of 245) of cases. The procedure was changed from Epi-off to TE-CXL and from TE-CXL to Epi-Off in 3.67% and 1.63% of the cases, respectively.

Anterior segment optical coherence tomography stromal thickness maps have minimal impact on the surgical decision making for conventional Epi-off and TE-CXL protocols. Considering that MinST data provide objective information on stromal thickness, unlike TCP, and avoid the need for deepithelialization, their implications in sub-400 protocols may be greater.