Abstract
Background:
Ocular biometrics, such as corneal curvature, axial length, anterior chamber depth, and lens thickness, play a significant role in the development of refractive error and are essential in many clinical and research applications.
Objective:
To determine means and ranges for corneal curvature, axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and their intercorrelations with refractive error in Saudi adults.
Methods:
A total of 120 eyes of 60 hyperopic and 60 myopic subjects aged 19-26 years old were enrolled in this comparative cross-sectional study. Axial Length (AL), Anterior Chamber Depth (ACD), Lens Thickness (LT), and Vitreous Chamber Depth (VCD) were measured by the SONOMED ultrasound E-Z SCAN AB5500+, A-scan, with a contact technique. An ophthalmometer measured the refractive status objectively by auto-refraction and the corneal radius of curvature.
Results:
The findings showed that the myopic eyes had a deeper ACD(3.70 +/- 0.27mm) than hyperopic eyes ( 3.28 +/- 0.32mm), P=0.0001. However, the hyperopic eyes had a thicker LT (3.84 +/- 0.24mm) than the myopic eyes (3.81 +/- 0.19mm), P=0.640. The mean of the corneal radius of curvature for the myopic eyes was slightly more curved (7.87 +/- 0.23mm) than for the hyperopic eyes (7.95 +/- 0.27mm), P=0.602. The myopic eyes had a higher axial length/ corneal radius AL/CR ratio (3.12 +/- 0.11) than hyperopic eyes (2.89 +/- 0.06), with P=0.0001. Myopic spherical equivalent (SPH) positively correlated with VCD and AL/CR ratio, P=0.0001. Vitreous chamber depth/Axial length ratio (VCD/AL) in the myopic eyes was higher (0.693 +/- 0.041) than in the hyperopic eyes (0.677 +/- 0.018), P=0.000. Hyperopic SPH was positively associated with the VCD/AL ratio, P=0.0001.
Conclusion:
Myopic eyes had a deeper VCD than hyperopic eyes; there was a strong positive correlation between VCD and myopic SPH. There was a strong positive correlation between the AL/CR ratio and myopic SPH and a VCD/AL ratio and the hyperopic SPH. Thus, the study suggests the possible utility of the AL/CR ratio while assessing the development of myopic refractive error and the VCD/AL ratio when evaluating hyperopic eyes and their associated complications.