Vascular disease of the retina. Retinopathy of prematurity.
- Diabetic retinopathy
- a pathological change in the retinal vessels due to the microangiopathy that occurs in diabetes mellitus
Pathpgenesis:
- DR is microangiopathy primarily affecting the pre-capillary arterioles, capillaries and post-capillary venules.
- Microvascular occlusion:
- capillary changes
- consist of loss of pericytes, thickening of the basement membrane and damage and proliferation of endothelial cells
- haemathological changes
- deformation of red blood cells and increased platelet stickiness and aggregation, leading to decreased oxygen transport.
The consequence of retinal capillary non-perfusion is retinal ischemia leading to neovascularization
- Microvascuar leakage
- Breakdown of the inner blood-retinal barrier leads to leakage of plasma into the retina. Physical weakening of the capillary walls results in to microaneurysms, which may leak or become thrombosed
- Consequence of the increased vascular permeability include the development of intraretinal haemorrhages and edema (diffuse or localized)
Classification:
- NPDR Non-proliferative diabetic retinopathy) is subdivided into:
- Mild NPDR: micro-aneurysms only
- Moderate NPDR: more than just microaneurysms but less than severe
- Severe NPDR: consisting of any of the following intra-retinal hemorrhage in each of the four quadrants, venous beading in two or more quadrants, or intraretinal microvascular abnormalities (IRMAs) in one or more quadrants AND no signs of proliferative retinopathy
- PDR (proliferative diabetic retinopathy)is defined as neovascularization at the optic disc (NVD) or elsewhere (NVE)
Symptoms of diabetic retiopathy:
- Progressive decrease of vision up to blindness
- NPDR
- Microaneurisms-tiny, round, red dots
- Hard exudates -waxy, yellow lesions with relatively distinct margins
- Retinal edema- retinal thickening
- Haemorrhages – “dot-blot” configuration or flame-shaped
- PDR:
- Cotton wool spots – small, whitish, fluffy superficial lesions that represent focal infarcts of the retinal nerve fiber layer, due to occlusion of pre-capillary arterioles
- Intraretinal microvascular abnormalities (IRMA)- represent shunts that run from retinal arterioles to venules, looks like fine red lines
- Venous changes -dilatation, looping and “sausage-like” segmentation
- Arterial changes- narrowing, silver-wiring and obliteration
- Dark blot haemorrhages -represent haemorrhagic retinal infarcts
Ophthalmoscopic Findings and Classification
- Non-proliferative retinopathy (mild, moderate, severe)
- Microaneurysms
- Light intraretinal microvascular anomalies (IRMA)
- Intraretinal bleeding
- Hard exudates
- Retinal edema
- Caliber variations of the veins ("bead-like")
- Cotton wool spots
- Proliferative retinopathy: Preretinal neovascularization (neoplasm of blood vessels) defines the transition to the proliferative form, possible findings are:
- Fibrovascular membranes
- Vitreous hemorrhage, if necessary with Traktionsamotio
- Rubeosis iridis → secondary glaucoma, additional changes as in non-proliferative retinopathy
- Diabetic maculopathy
- Clinically significant macular edema
- Retinal edema
- Hard exudate in the area of the macula
- Ischemic maculopathy