Biometry of the lens with respect to age and cataract morphology. Evaluation of Scheimpflug photos of the anterior segment

Abstract

Thickness of the lens, cortex and nucleus or nucleus with supranuclear layer, respectively, were determined for 58 controls aged 11-69 years (115 lenses), and for 175 patients aged 30-86 years with different types of cataract (247 lenses). Measurements of the densitograms of Scheimpflug photos (taken along the optical axis, magnified 10-fold) were performed, accurate to 0.5 mm (corresponding to 0.05 mm original size). The cataractous lenses were grouped in 5 morphological classes and 3 degrees of opacification (density according to the Scheimpflug photos). As regards normal lenses, the present authors' findings correspond to earlier findings of Niesel et al. (1976). Deviations from the normal pattern are found in typical cortical cataract (water-cleft and spokes cataract, wedge-shaped cataract) where nucleus and nucleus with supranuclear layer are thinner than the normal lenses, while with nuclear cataracts and mixed types the opposite is the case. In eyes with posterior cortical opacities no increase in the thickness of the anterior cortex is found with aging. With the true nuclear cataracts the increase in the thickness of the anterior cortex is negligible. The degree of opacification is closely related to an increase in the thickness of the nucleus and supranuclear layer, which implies a decrease in the thickness of the anterior cortex. Water-clefts and spokes of larger size cause the anterior cortex to become thinner. In eyes with wedge-shaped cataracts the different degrees of opacification did not affect the parameters measured.