Genetic studies, suggest that diabetic retinopathy is an interaction between
environmental factors, especially hyperglycaemia (1,2), and
several genetic factors
associated genes under study are aldose receptor, advanced glycation end products receptor, vascular endothelial growth factor, intercellular adhesion molecule 1, beta3-adrenergic receptor gene, hemochromatosis, and alpha2beta1 integrin (1).
The retinopathy in diabetes result from five fundamental processes (2):
retinal capillary microaneurysms
excessive vascular permeability
vascular occlusion
proliferation of new blood vessels and accompanying fibrous tissue
contraction of fibrovascular proliferations and vitreous.
Duration of diabetes and severity of hyperglycemia are the major risk factors for developing retinopathy (2).
Severity of hyperglycemia is the key alterable risk factor.
Increased retinal blood flow results in microaneurysm formation in capillaries, precapillary arterioles and venules, leading to occlusion and transudation of fluid and lipid.
Hyperglycaemia is the cause of high retinal blood flow.
Other factors include pregnancy and high blood pressure.
Occlusion of capillaries results in retinal ischaemia with compensatory neovascularisation on the retina, iris, and optic disc (proliferative retinopathy).
Ischaemic retina may express an unknown vasoproliferative substance leading to new vessel formation.
Vitreous haemorrhage may occur as a result of bleeding from new vessels.
Fibrous tissue is carried along with the new vessels; there is an increased risk of retinal detachment as a result of retraction of this tissue.
Cotton wool spots occur secondary to occlusion and represent retinal microinfarcts.
Retinal thickening, oedema and hard exudates occur as a result of leakage from capillaries; hard exudates are composed of lipoprotein and lipid filled macrophages.
Flame-shaped haemorrhages occur when rupture of microaneurysms occurs at nerve level.
Blot haemorrhages occur if rupture of microaneurysms occur deep in the retina.
Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.