We compared the human lens documented, using the Scheimpflug densitometry, with the light microscopic changes in the epithelium of the anterior central lens in patients with age-related cataract and diabetes mellitus type II and verified the findings on the control tissue of the clear eye lens. We wanted to determine the relevance of the lens epithelium in cataract formation in type II diabetics compared to non-diabetics. One hundred fifty central lens capsules (138 cataract and 12 clear lenses) of type II diabetics (n=77, 45 female, 32 male) and non-diabetics (n=73, 41 female, 32 male) were examined by light microscope, regarding defined histomorphological parameters. Further criteria were duration of diabetes, diabetic retinopathy, cataract (PENTACAM, scheimpflug densitometric definition), protein content in the aqueous humour (laser flare meter 500 KOWA, tyndallometry), different blood parameters and glucose content in the aqueous humour. The mean cell density in the cataractous lens in type II diabetics was 3,951 +/- 528 cells/mm(2) and in non-diabetics 4,329 +/- 580 cells/mm(2) (P < 0.001); in the clear lens it corresponded to 4,593 +/- 409 cells/mm(2) (type II diabetics) and 4,894 +/- 333 cells/mm(2)(non-diabetics, P=0.207). The cell density of the cataractous lens in type II diabetics (P=0.005) and in non-diabetics (P=0.035) is smaller than that of the clear lens. The cell area of the lens epithelium in the cataractous diabetic lens is larger (P < 0.001) and the nucleus-plasma ratio is lower (P < 0.001) than those of the clear non-diabetic lens. The increase in damage of the lens epithelium correlates with the decrease of cell density (P < 0.001), the increase of nucleus area and volume (P < 0.001), and the decrease of nucleus-plasma ratio (P < 0.001). Risk factors for the decrease of cell density are advanced age (P=0.015), type II diabetes (P=0.01), increase in glucose content in the aqueous humour (P=0.014), increase in blood sugar (P=0.003) and increase in glycosylated haemoglobin (P=0.039). The lens epithelium is primarily damaged in type II diabetics who develop age-related cataract. This might play an important role in cataract formation.
