Systemic Diseases
Diabetic RetinopathyOne of the most important causes of blindness
Risk factors: 1-Type of diabetes. More common in type I ( insulin dependent, 40 %), than type II (non-insulin dependant, 20%). 2-Duration of diabetes. After 10 years 50% have retinopathy, while after 30 years 90% have retinopathy 3-Poor metabolic control 4-Hypertension 5-Nephropathy 6-Pregnancy 7-Other factors; smoking, obesity, hyperlipidaema.
Pathogenesis: It is a microangiopathy, affecting pre-capillary arterioles, capillaries, and post-capillary venules.
1- Micro-vascular leakage due to loss of pericytes which are responsible for structural integrity of capillaries. There will be saccular out pouching of the capillaries (microaneurysms) and increase leakage of fluids. Chronic retinal edema lead to deposition of hard exudates which compose of lipoproteins. 2- Micro-vascular occlusion due to thickening of the basement membrane, and increase stickiness of platelets. Micro vascular occlusion cause retinal ischemia and secretion of vaso-formative factors which promote abnormal neo-vasculartization on the surface of the retina (NVE) and on the optic disc (NVD).
Classification of diabetic retinopathy;
1-Background (non-proliferative) microaneurysms, Retinal hemorrhages (blot and dots ), and hard exudates.2-Maculopathy, clinical significant macular edema. Microaneurysms, hemorrhages, and hard exudates at the macula. Vision gradually reduced
3-Pre-proliferative. Large retinal hemorrhage, cotton wool spots (infarction in the nerve fiber layer), venous congestion and dilatation.
4-Proliferative retinopathy. Abnormal neo-vasculartization on the surface of the retina (NVE) and on the optic disc (NVD).
5-Advanced retinopathy. Vitreous hemorrhage and tractional retinal detachment.
Management: Early Detection of Diabetic Retinopathy regular ophthalmic examination for detection retinopathy.Treatment : Background; good diabetic control Maculopathy; Laser phototherapy. Laser burns are directed at the sites of leakage ( micro-aneurysms), avoiding the central fovea. Pre-proliferative and Proliferative retinopathy; Laser phototherapy. The entire retina is treated with laser burns except the macula and area adjacent to the optic disc. Pan retinal photocoagulation (PRP) The Laser burns destroy the ischemic retina and prevent release of vaso-formative factors and causing regression of the abnormal vessels.
Advanced retinopathy; Surgery (Pars Plana Vitrectomy). Removal of the vitreous hemorrhage, vitro-retinal bands and endo-laser through small incisions at pars plana (posterior part of the ciliary body).