Comparative Evaluation of the Corneal and Anterior Chamber Parameters Derived From Scheimpflug Imaging in Arab and South Asian Normal Eyes

Purpose:To evaluate the differences in the normal corneal and anterior segment Scheimpflug parameters in Arab and South Asian eyes.Methods:This hospital-based study was performed at a cornea and refractive surgery service in Abu Dhabi. A total of 600 consecutive normal candidates of South Asian (group 1, n = 300) and Arab (group 2, n = 300) origins underwent Scheimpflug imaging (Sirius; Costruzione Strumenti Oftalmici, Italy). One eye was randomly selected for evaluation.Results:The age and sex distributions in both groups were comparable. The pachymetric variables were statistically higher in group 2 (group 2 vs. group 1, 544.3 32.2 m vs. 535.1 +/- 31.4 m for central corneal thickness, 541.0 +/- 32.6 m vs. 531.9 +/- 31.5 m for minimum corneal thickness, 571.7 +/- 43.2 m vs. 558.1 +/- 42.3 m for apical thickness, and 58.1 +/- 4.2 vs. 57.3 +/- 4.3 mm(3) for the corneal volume; P < 0.05). The anterior chamber volume (group 2 vs. group 1: 166.4 +/- 16.4 vs. 161.6 +/- 20.5 mm(3)) and angle (group 2 vs. group 1: 44.6 +/- 6.2 vs. 43.5 +/- 5.8 degrees) were also higher for group 2 (P < 0.05). Central corneal curvature and apical corneal curvature (apex K) were higher in group 1 (P < 0.05) with comparable astigmatism. The flat keratometry (K), steep K, and apex K were 43.6 +/- 2.2 diopters (D), 44.9 +/- 1.8 D, and 45.7 +/- 1.8 D for group 1, and 43.1 +/- 2.2 D, 44.5 +/- 2 D, and 45.2 +/- 1.9 D for group 2. The effect size (Cohen d) for significant parameters ranged from 0.2 to 0.3.Conclusions:Normal eyes of Arab ethnicity tend to have statistically thicker and flatter corneas and less-crowded anterior segments than those of the South Asian counterparts. These epidemiological differences have a mild to moderate biological effect size (Cohen d), but they should be considered when evaluating these eyes for anterior segment or corneal procedures.