Corneal Pachymetry by AS-OCT after Descemet's Membrane Endothelial Keratoplasty

TL;DR

This study employs deep learning to automatically delineate corneal interfaces in AS-OCT images post-DMEK, achieving high accuracy in measuring corneal thickness and enabling detailed pachymetry mapping for better postoperative assessment.

Contribution

The paper introduces three deep learning strategies for automatic corneal interface delineation in post-DMEK AS-OCT images, improving measurement accuracy and enabling detailed pachymetry mapping.

Findings

Corneal thickness measurement error less than 16 micrometers.

Achieved less than 3% error relative to average corneal thickness.

Enabled creation of detailed and differential pachymetry maps.

Abstract

Corneal thickness (pachymetry) maps can be used to monitor restoration of corneal endothelial function, for example after Descemet's membrane endothelial keratoplasty (DMEK). Automated delineation of the corneal interfaces in anterior segment optical coherence tomography (AS-OCT) can be challenging for corneas that are irregularly shaped due to pathology, or as a consequence of surgery, leading to incorrect thickness measurements. In this research, deep learning is used to automatically delineate the corneal interfaces and measure corneal thickness with high accuracy in post-DMEK AS-OCT B-scans. Three different deep learning strategies were developed based on 960 B-scans from 50 patients. On an independent test set of 320 B-scans, corneal thickness could be measured with an error of 13.98 to 15.50 micrometer for the central 9 mm range, which is less than 3% of the average corneal thickness. The accurate thickness measurements were used to construct detailed pachymetry maps. Moreover, follow-up scans could be registered based on anatomical landmarks to obtain differential pachymetry maps. These maps may enable a more comprehensive understanding of the restoration of the endothelial function after DMEK, where thickness often varies throughout different regions of the cornea, and subsequently contribute to a standardized postoperative regime.