Pre-proliferative diabetic retinopathy
 

Multiple cotton wool spots in preproliferative diabetic  retinopathy Vascular loop in preproliferative diabetic  retinopathy

In addition to background diabetic retinopathy (dot and blot haemorrhages, microaneurysms and hard exudates). The retina shows signs of ischaemia which may be: venous abnormalities with venous loop, tortuosity and beading multiple cotton wool spots intra-retinal microvascular abnormalities (IRMA, which is caused by dilated retinal capillaries).  Note: this may be confused with neovascularization but appear flat and tend to be between the artery  and the vein. Look for: associated maculopathy neovascularization of the disc and the periphery hypertensive retinal changes

Questions:

1. What are the risk factors for a diabetic patient to develop diabetic retinopathy?

Answer
age of the patient: before puberty diabetic retinopathy is rare
duration of diabetes: 75% of patients have some degrees of retinopathy 10 years after the development of diabetes mellitus
control of diabetes: The Diabetic Control and Complication Trial (CSST) shows that patients with poorly controlled diabetes mellitus are at greater risk of developing retinopathy
renal disease: patients with proteinuria are at greater risk of developing severe retinopathy
systemic hypertension
pregnancy
hyperlipidaemia

2. What are the mechanisms of retinopathy in diabetes mellitus?

Answer
The two mechanisms are :
increased permeability of the blood vessels
ischaemia resulting from capillary closure

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