Detecting Subclinical Corneal Edema Using Corneal Thickness Mapping in Patients Presenting Fuchs Endothelial Corneal Dystrophy

To determine whether local corneal thickness changes observed with optical coherence tomography (OCT) can detect subclinical corneal edema in Fuchs endothelial corneal dystrophy (FECD).Retrospective cohort study.A series of patients presenting FECD who underwent cataract surgery alone (45 eyes) or with concomitant Descemet membrane endothelial keratoplasty (triple procedure; 117 eyes). The study reviewed medical records, collected the preoperative corneal thickness map and calculated the differences and ratio of corneal thickness measured at 5, 7, and 9 mm from the central corneal thickness. Area under the receiver operating characteristic curves (AUCs) were calculated and thresholds were selected to obtain a specificity of 90%.The median difference between 5- and 2-mm corneal thickness in the supra-nasal quadrant (∆5-2mmSN) was 38 µm (interquartile range 34-46) in the cataract group and 17 µm (2-38) in the triple procedure group (P < .001). The corneal thickness ratios of supra-nasal 5- to 2-mm (R5/2mmSN) and 7- to 2-mm (R7/2mmSN) were 1.07 (1.06-1.08) and 1.15 (1.13-1.17)] in the cataract group and 1.03 (1.00-1.06) and 1.09 (1.06-1.14) in the triple procedure group (P < .001). The probability of corneal edema was increased 7-fold with ∆5-2mm SN < 27 µm (AUC = 0.76) and 9.4- and 7.4-fold with R5/2mmSN and R7/2mmSN < 1.045 (AUC = 0.77) and 1.118 (AUC = 0.76), respectively.Local changes in corneal thickness may be useful in detecting preclinical corneal edema, especially in patients with FECD undergoing cataract surgery.