New algorithm for corneal densitometry assessment based on anterior segment optical coherence tomography

Abstract

Purpose: To describe a new algorithm to measure corneal densitometry based on images obtained by swept source anterior segment ocular coherence tomography (SS-AS-OCT) and establish standard densitometry values in a group of normal eyes. Methods: A total of 111 healthy participants (195 eyes) were enrolled in this study. Using a MATLAB designed algorithm, the cornea was segmented into three layers: anterior, posterior and mid-stroma, and it was divided into two concentric areas, 0–2 and 2–4 mm, resulting in nine areas for the analysis. The mean corneal densitometry values were calculated and expressed as grayscale units (GSU). Results: The mean age was 57 years (range 22–87), with 100 (51.3%) right eyes and 95 (48.7%) left eyes. The total corneal densitometry was 86.9 ± 12.1 GSU. The mid-stroma layer had the highest densitometry values, 87.4 ± 12.1 GSU, and the anterior layer had the lowest values, 81.9 ± 14.2 GSU. Densitometry differences between the anterior layer and the mid-stroma layer (P < 0.001), as well as the anterior layer and the posterior layer (P < 0.05) were statistically significant. The 0–2 mm concentric area had higher mean densitometry values, 97.8 ± 12.7 GSU, and the differences were significant compared to the 2–4 mm concentric area (P < 0.001). No correlation was found between the corneal densitometry values and gender or age. Conclusions: The new MATLAB segmentation algorithm for the analysis of corneal SS-AS-OCT images is capable to objectively assess corneal densitometry. We provide standard and normal data for better clinical and research approach.