Diabetic retinopathy

Diabetic retinopathy

The incidence of diabetic retinopathy is related more to the duration of D.M than to any other factor .the diabetic patient diagnosed before age of 30 years. 50%will have D.R after 10 years and 90% will have D.R after 30 years.
Pathogenesis:
It is essentially a micro angiopathy affecting the retinal arterioles, capillaries and the venules however larger vessels may also become involved. D.R has features of both
A- Micro vascular occlusion:
Consequences:
A-Micro vascular occlusion:
cause retinal ischemia which cause----retinal hypoxia and the main effect of retinal hypoxia is neovascularization which is thought to be due to vaso-formative substance released by hypoxic retinal tissue in order to re-vascularise the hypoxic areas of the retina
B- leakage:
In diabetic patients, there is reduction in the number of pericytes which thought to be responsible for the structural integrity of the vessel wall, so reduction in the number of pericytes is thought to be responsible for the distension of the capillary wall and disruption of blood- retinal barrier leading to leakage of plasma constituents into the retina that result in retinal edema, hemorrhage, exudates
Micro –aneurysms are saccular pouches which may form as a result of local distention of the capillaries
Classification of D.R.:
Background D.R.
Maculopathy which include
Focal b- diffuse c- ischemic
3-Pre-proliferative D.R.
4-Proliferative D.R.
5- Advanced diabetic eye diseases which include:
Persistent vitreous hemorrhage b- retinal detachment
Neovascular glaucoma
Clinical features of background D.R.:
1-Microaneurysms: which are the first clinically detectable lesions of D.R appear as small round red dots
2- Hemorrhage: the clinical appearance of retinal hemorrhage depend on its location within the retina e.g. dot and blot hemorrhage located within the middle layers of the retina , flame shape hemorrhages located in the nerve fiber layer of the retina
3-Hard exudates: composed of lipo- proteins and lipid laden macrophages. Hard exudates have a yellow waxy appearance with relatively distinct margins and are distributed in circinate pattern peripheral to areas of chronic focal leakage. The centre of the ring of the hard exudates usually contain micro aneurysms
4-Retinal edema: this is due to increase permeability of retinal capillaries and it is characterized by retinal thickening
O.E/ the thickened edematous retina obscure the visualization of the underlying retinal pigment epithelium and the choroid
Management:
1-good metabolic control: it is suggested that good initial control of D.M retard but not prevent the development of D.R
2-hypertension:strict control of systemic hypertension is important in diabetic patients in order to prevent detrimental effects to the retinal circulation
3-correction of anemia
4-aspirin or Dipyridamole (persantin) to decrease platelets stickness