Diabetic Retinopathy describes the retinal changes that occur in patients with diabetes mellitus. These changes affect the small blood vessels of the retina and may lead to vision loss through several different mechanisms. The main types of diabetic retinopathy are non-proliferative and proliferative diabetic retinopathy. The main distinguishing feature between these two categories is the presence (proliferative) or absence (non-proliferative) of abnormal new (neovascular) blood vessels (retinal neovascularization).
The central retina area which is located between the main branches (superior and inferior arcades) of the central retinal vessels (central retinal artery and central retinal vein) is the area which can develop abnormal findings in diabetic retinopathy. These findings can be present in the non-proliferative or the proliferative forms of the disease. These changes in the macula include the presence of abnormally dilated small vessels, retinal bleeding (retinal hemorrhages) and yellow lipid and protein deposits (hard exudates). The macula can get thicker than normal- referred to as macular edema.
Diagnostic procedures used in diabetic retinopathy may include fluorescein angiography to determine the degree of ischemia or the presence of retinal vascular abnormalities. Ocular coherence tomography (OCT) is useful to determine the retinal thickness measurements. The OCT can be used longitudinally to determine whether the macular thickening is responding (swelling/ edema is decreasing) to treatment.
Non-proliferative retinopathy can be classified into mild, moderate or severe stages based upon the presence or absence of retinal bleeding, abnormal venous beading of the vessel wall (venous beading) or abnormal vascular findings.
Proliferative retinopathy is progressive and requires treatment to prevent bleeding and scar tissue formation.
Treatment of macular edema is usually needed in order to prevent loss of vision or to try to improve vision. Treatment includes the use of lasers or injection of drugs that cause the swelling (from leaking blood vessels) to resolve. Patients are typically seen monthly if being treated by injections or every three months if they have received laser for macular edema.
Treatment of proliferative diabetic retinopathy may involve laser photocoagulation of the peripheral retina. The laser is used to create scars on the peripheral retina. If successful, bleeding and scarring is averted. Sometimes the proliferative disease is advanced and there is bleeding filling the eye (and preventing laser to be done) or scar tissue that wrinkles the retina or causes areas of detachment. In these situations, surgery may be necessary.