Dr Simon Barnard Phd BSc FCOptom FAAO DCLP
Most tissues are pervaded by blood vessels and lymphatic vessels. Nutrition, respiration and other metabolic activities rely on proper local vascular supply.
Interference with movement of blood, lymph and tissue fluid are frequently discussed under the following headings:-
Obstructive diseases of the arteries
Diminution of arterial blood supply leads to ischaemia ® necrosis ® atrophy ® degeneration ® replacement fibrosis.
Such diseases that may affect the retina include:
Local affects of arterial obstruction depend on the size of artery, importance of tissue supplied, speed of occlusion, and whether there is any collateral circulation.
The central retinal artery is an "end artery".
This is an abnormal dilatation of an artery. Aneurysms may produce
Venous obstruction may be the result of
The effects will depend on the degree and speed of obstruction. If the obstruction occurs gradually there may be time for collateral vessels to be established. If not, then congestion, oedema, and haemorrhages may result (e.g. CRV occlusion).
Effects of vascular disease on the retinal blood vessels
all can be observed by the clinician by ophthalmoscopy.
Such disease include
Arteriosclerosis may be divided into the following categories based upon aetiology:
Arteriosclerosis first effects the blood vessel walls and only in the late stages will produce the haemorrhages and exudates which is then termed a retinopathy.
Although purely hypertensive retinopathy can occur in chronic hypertension, the condition will be invariably be accompanied by arteriosclerosis.
Effects of arteriosclerosis/hypertension on the retina
There may be an observable change in "a/v" ratio from the "normal" 2:3.
Pathological changes include:
Apart from vascular hypertension and arteriosclerosis, other conditions/associations which may affect the retinal vascular tree include:
Alexander L. (1995) Primary Care of the Posterior Segment. Appleton & Lang,
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