Decreased epithelial to corneal thickness ratio in healthy fellow eyes of patients with unilateral bullous keratopathy

Abstract

Purpose: To study the relationship between epithelial thickness (ET) and corneal thickness (CT) in healthy fellow eyes of patients with unilateral bullous keratopathy (BKP) and healthy subjects.

Methods: Seventeen BKP patients (nine males, eight females, 73.2±10.4 years) and 40 healthy individuals (20 males, 20 females, 69.5±9.8 years) were included. All participants received anterior segment optical coherence tomography and specular microscopy with calculation of endothelial cell density. ET, CT, stromal thickness and ET-to-CT ratio were defined automatically (within 2 mm central area). Central epithelial thickness (CET) and central corneal thickness (CCT) were measured manually at the corneal centre and stromal thickness and CET-to-CCT ratio were calculated.

Results: In healthy fellow eyes of BKP patients compared with eyes of healthy individuals ET was statistically significantly lower (p<0.001) while CT was statistically significantly higher (by 28.9 and 30.9 µm in 2 mm zone and corneal centre, respectively). Both 2 mm ET-to-CT ratio (0.091±0.01 and 0.10±0.004, respectively [p<0.001]) and CET-to-CCT ratio (0.083±0.006 and 0.97±0.005, respectively [p<0.0001]) were statistically significantly lower in healthy fellow eyes of BKP patients compared with eyes of healthy individuals. To identify healthy fellow eyes of BKP patients, area under curve for CET-to-CCT ratio and CET was 0.94 and 0.80, respectively (p=0.01), and for 2 mm ET-to-CT ratio and 2 mm ET was 0.91 and 0.80, respectively (p=0.03).

Conclusion: Decreased СET-to-СCT ratio resulting from simultaneous epithelial thinning and stromal thickening without significant corneal thickening indicates subclinical dysfunction of corneal endothelium in healthy fellow eyes in unilateral BKP patients.

Keywords: anterior segment optical coherence tomography; bullous keratopathy; corneal endothelium; corneal epithelium thickness; corneal thickness; fuchs endothelial dystrophy.