Diabetic maculopathy
 

Clinically significant macular oedema. Diabetic maculopathy treated with argon laser.

Note: This is a very popular case, you must demonstrate to the examiner(s) that you know what is meant  by significantly macular oedema (this is done through physical examination and not fluorescein angiography).  The maculopathy may occur in background diabetic retinopathy or in association with preproliferative or  proliferative diabetic retinopathy. The clinical appearance of the maculopathy alone cannot distinguish between  ischaemic from non-ischaemic maculopathy. There are multiple dot and blot haemorrhages, microaneurysms and  hard exudates (which may be circinate and  form around a leaking microaneurysm). The presence of macula oedema is regarded as clinically significant if: a. retinal thickening at or within 500um of the centre of the macula b. hard exudates at or within 500um of the macular centre if associated with thickening of the      adjacent retina c. retinal thickening at least one disc area in extent, any part of which is within one disc diameter of the      macular centre.

Questions:

1. What is the most common cause of visual loss in diabetic retinopathy?

Answer
Macular oedema is the most common cause. Vitreous haemorrhage and tractional retinal detachment are less common though the loss of vision can be more profound.

2. Is fluorescein angiography essential in deciding treatment for diabetic maculopathy?

Answer
Clinical examination is the most important in deciding if the patient had significant diabetic maculopathy. Fluorescein angiography is useful in pinpointing the source of leakage in macular oedema and differentiating between ischaemic and non-ischaemic diabetic maculopathy. However, in most clinical cases clinical examination is sufficient.

3. What are the results of ETDRS (Early Treatment of Diabetic Retinopathy Study) with regard to treatment of clinically significant macular oedema?

Answer
ETDRS showed that macular laser reduced the risk of visual loss in patients with clinically significant macular oedema. In the Study, the risk of doubling the visual angle (for example from 6/9 to 6/18) was reduced from 24% to 12% over a 3-year period for all levels of visual acuity. The resolution of macular oedema usually takes a few months. However, significant visual improvement was uncommon after laser treatment.

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