The vessels, when undergoing structural alterations, dilate and cease to be watertight, causing bleeding and exudation of liquid. Edema and bleeding appear in the retina (retinopathy). Vision may or may not be affected depending on the extent and location of the lesions, and the lesions affecting the central portion (macula) are more severe. 

The deficient oxygenation of the retina stimulates the development of new, weaker vessels, which are the source of new haemorrhages and exudations. Diabetes affects about 1 million Portuguese.

Diabetes Type 1:
It comprises 10% of the cases and manifests itself in childhood or adolescence and must be treated with insulin.

Diabetes Type 2:
It covers 90% of cases, manifests itself from the age of 45 and can be controlled with diet, exercise and oral medication, resulting in many in also needing insulin.

The eyes are among the most affected organs, with diabetes being a major cause of blindness in the developed world. When diagnosed with diabetes it should be carried out a, strict, effective and systematic monitoring of blood glucose leves, blood pressure and cholesterol. The practice of exercise is fundamental.

Early intervention through the patient's commitment and modern medicines and treatments, before a decrease in vision, allows to control the ocular disease and the consequent partial or total irreversible vision loss.