40) retinal changes in vascular diseases- atherosclerosis, hypertension and diabetes mellitus.
The eye is the one structure in the body in which the blood vessels are easily visible to the examiner. Changes observed in the retinal vessels mirror changes that are taking place in other parts of the body, particularly those in the brain.
In arteriosclerosis, degenerative changes occur in the walls of arteries that lead to thickening of arterial walls and narrowing of blood vessels and may give rise to complete occlusion (blockage) of a vessel. If the central retinal artery that supplies blood to the inner retina is affected, loss of vision is profound and sudden and, unless the obstruction can be relieved right away, permanent. Occlusion of the retinal veins is more common than arterial occlusion and has dramatic effects caused by the damming up of blood in the eye. Blockage of retinal veins results in the bursting of small vessels, retinal swelling, and multiple haemorrhages scattered over the retina. Some degree of recovery of vision is usual but depends on whether a branch of the central vein or the central vein itself is occluded.
Vascular hypertension, or raised blood pressure, usually occurs in association with arteriosclerosis. Typical changes can be recognized in the small vessels of the fundus (the back portion of the interior of the eyeball). In severe cases, multiple haemorrhages, exudates (leaking proteinaceous fluid), and swelling of the optic disk (the head of the optic nerve) may be present. As with arteriosclerosis, hypertension can lead to vascular occlusions of the retina. The presence of hypertension typically worsens the effects of diabetic eye disease in patients having both afflictions.