Accuracy of OCT Curvature and Aberrations of Bowman's Layer: A Prospective Comparison With Physical Removal of Epithelium.

PURPOSE: To compare optical coherence tomography (OCT) and Scheimpflug curvature and aberrations of the Bowman's layer before and after removal of the epithelium.

METHODS

Bowman's layer was mapped with OCT (Optovue Inc., Irvine, CA) before and after removal of the epithelium in normal eyes undergoing photorefractive keratectomy (n = 14) and keratoconic eyes undergoing corneal cross-linking (n = 25). The anterior corneal surface before removal and the underlying Bowman's layer after removal of the epithelium were also mapped with Pentacam (Oculus Optikgeräte, Wetzlar, Germany), and the surface aberrations with ray tracing were computed.

RESULTS

The agreement of OCT curvatures before and after removal of the epithelium was excellent (intraclass correlation coefficient [ICC] = 0.9). A similar trend was seen between OCT and Pentacam after removal of the epithelium. The agreement of surface wavefront aberrations of the Bowman's layer before and after removal of the epithelium was excellent (ICC = 0.9) between the devices for keratoconic eyes. However, this agreement was relatively inferior in normal eyes (ICC < 0.5).

CONCLUSIONS

The virtual OCT curvature and aberrations of the Bowman's layer agreed well with its actual magnitudes on removal of the epithelium in the keratoconic eyes. In normal eyes, the agreement was inferior for aberrations but not for curvature. [J Refract Surg. 2020;36(3):193-198.].