Purpose To examine the early differences in the thicknesses of the macula and retinal nerve fibre layer (RNFL) by Stratus optical coherence tomography in patients with diabetes mellitus. Methods Thirty-one normal participants without any optic nerve and retinal diseases (control), 45 diabetic patients without diabetic retinopathy (NDR), and 24 diabetic patients with preproliferative diabetic retinopathy (PPDR), who did not have clinically significant macular oedema, were used for the macular thickness measurements. Thirty control participants, 45 patients classified as NDR, and 22 patients classified as PPDR were used for the RNFL thickness measurements. Results In patients with NDR, macula was significantly thinner than that of control eyes. In patients with PPDR, the mean RNFL thickness was significantly thinner but the macula was thicker than that of control eyes. In women with NDR, the macula was significantly thinner than that of men with NDR and that of normal women. In men with PPDR, the RNFL thickness was significantly thinner than that of the control eyes. Conclusions At the early stage of diabetic retinopathy, the maculas and RNFL thicknesses are altered. The macular and RNFL thicknesses are different in men and women.

Diabetes mellitus is a major disease worldwide, and the prevalence of diabetes has risen significantly in the past several decades. Although one of the major complications of diabetic eyes is diabetic retinopathy (DR), corneal diseases can not only develop in diabetic patients but are also difficult to manage. Diabetic neurotrophic keratopathy is a component of diabetic polyneuropathy and is recognized to be the cause of the morbidity of the cornea in diabetic patients. In addition, corneal endothelial cell damage can cause disturbances in the management of proliferative DR before and after surgeries because of endothelial decompensation with bullous keratopathy. However, there have been only a limited number of studies that have focused on the importance of corneal diseases in diabetic patients. This review describes the pathophysiological roles of different factors that have been found to be causative factors of diabetic corneal keratopathy and endothelial cell dysfunction in diabetic patients. In addition, the clinical features of the corneal changes in diabetic patients and recent studies related to the development of therapies for the management of corneal diseases are presented.

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Upregulation of Bax, caspase-9 and -3 expression was associated with neuronal degeneration in diabetic retinopathy. The mitochondria- and caspase-dependent cell-death pathway may be, in part, associated with neuronal degeneration in diabetic retinas.