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 μm vs. 535.1 ± 31.4 μm for central corneal thickness, 541.0 ± 32.6 μm vs. 531.9 ± 31.5 μm for minimum corneal thickness, 571.7 ± 43.2 μm vs. 558.1 ± 42.3 μm for apical thickness, and 58.1 ± 4.2 vs. 57.3 ± 4.3 mm³ 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 mm³) 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.