Age–related changes in the optical and geometric properties of the cornea.

Abstract

Abstract: : Purpose: To analyze the influence of the aging on the optical and geometric properties of the cornea using Orbscan. Methods: Optical properties and geometric characteristics of the cornea were prospectively analyzed with Orbscan in 300 'normal' eyes (apart from eyes with possible ametropia) of 150 patients from 10 to 95 years old. The mean astigmatism and enantiomorphism (mirror–image symmetry) were analyzed using Cartesian coordinates in a 'dioptric plane'. Irregular astigmatism was quantified using semi–meridian data. The optical and biometric corneal parameters were compared in different age groups and were correlated with the age of patient. Results: The pachymetry is correlated with the age (r_s=0.31 p<0.001). The central corneal thickness increases on average to 7 µm for each decade of life. The other corneal geometric parameters (i.e., corneal diameter, corneal radii of curvature, asphericity, localization of the thinnest point...) were not influenced by aging. The axis of regular astigmatism varies according to age group (p<0.001). Cylinder and corneal power are not significantly correlated with age. Enantiomorphism of astigmatism significantly decreases with age (r_s=0.24 p=0.002) whereas irregularity increases with age (r_s=0.26 p<0.001). Conclusions:Aging significantly influences corneal astigmatism (rotation of the axis, decreasing of the regularity and the enantiomorphism) and the thickness of the cornea.

Keywords: astigmatism • aging • cornea: clinical science