Diabetes mellitus is a hereditary illness caused by an alteration in sugar metabolism: diabetes causes alteration of blood vessels throughout the body, in particular, small vessels (capillaries), which carry blood to the tissues and exchange oxygen with for nourishment. Diabetic retinopathy is a localized manifestation of diabetes. Although every eye structure may be affected by the disease, the retina, rich in capillary vessels, is particularly affected by it. In the event that the blood hemorrhage extends to the vitreous body, the light rays can no longer pass through and reach the retina as is done under normal conditions, thus causes sudden loss of sight.
The retinal detachment caused by diabetic retinopathy is said to be traumatic: the neovasculars grow from the eye retina in the scaffold provided by the vitreous body. During this growth, membranes stick to the retina. Diabetic retinopathy usually affects the peripheral areas of the retina, but if the macula is affected, it may be possible, even at early stages, to obscure and reduce vision. Sudden vision loss may be due to intraocular hemorrhage or occlusion of a large vessel (thrombosis), which blocks the blood flow to the retina more or less completely.
In addition to the retinal fluoroangiography examination that allows for a detailed study of the retina and choroid blood circulation, the OCT (optical coherence tomography) is irreplaceable to complete the information provided by the former.