Ocular biometric characteristics in young Saudi adults across varying degrees of myopia

High myopia significantly increases the risk of serious ocular complications. The purpose of this study was to characterize ocular biometric variations across different degrees of myopia in young Saudi adults and to identify biometric parameters most strongly influenced by refractive severity.

In this cross-sectional study, 163 eyes from individuals aged 18-31 years with myopia ranging from -1.00 to -11.00 D were evaluated at the university medical clinics. Anterior segment parameters such as white-to-white (WTW) corneal diameter, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured using the Pentacam, axial length (AXL) was assessed with the IOL Master. Intraocular pressure (IOP) was measured with a non-contact tonometer. Finally, AXL, anterior chamber parameters, WTW, CCT and IOP were compared among the low, moderate, and high myopic groups.

Myopia severity showed a statistically significant positive correlation with AXL, WTW corneal diameter, ACD, ACV, CCT, and IOP (p < 0.05). AXL demonstrated a strong, statistically significant positive correlation with spherical equivalent (r = 0.70, p < 0.01). In contrast, ACA remained relatively stable across myopia groups. Multivariate analysis of covariance revealed that myopia severity significantly influenced AXL (F(2,156) = 8.52, p < 0.01), WTW corneal diameter (F(2,156) = 5.22, p < 0.01), ACV (F(2,156) = 7.94, p < 0.01), CCT (F(2,156) = 15.84, p < 0.01), and IOP (F(2,156) = 12.83, p < 0.01) after adjusting for age and gender. ACD showed modest increases across myopia groups with a borderline non-significant association after adjustment (F(2,156) = 2.93, p = 0.06), whereas ACA remained relatively stable and was not significantly affected by myopia severity (F(2,156) = 0.62, p = 0.54).

Myopia severity in young adults is associated with significant structural changes, primarily AXL elongation and only minimal enlargement of anterior segment dimensions particularly the ACD and ACA, suggesting that posterior expansion predominates over anterior. These biometric patterns have important implications for refractive surgery planning, glaucoma risk assessment, and monitoring of myopia progression.