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I would agree with Mr Dowler’s assessment of this patient with type 2 diabetes and very severe non-proliferative diabetic retinopathy in his right eye. Although the macular oedema is difficult to detect in non-stereoscopic fundus photographs of the macula, the presence of retinal hard exudates strongly suggests the presence of macular oedema. It is possible that this patient may have clinically significant macular oedema, although the retinal hard exudate is located a distance from the centre of fovea. His decreased visual acuity would also suggest the involvement of the fovea, either with macular oedema or possibly foveal ischaemia. It would be prudent to conduct a detailed funduscopy with biomicroscopy to view the macula stereoscopically and to perform a fluorescein angiogram. Optical coherence tomography (OCT) of the macula may be helpful. His systemic risk factors include the poor glycaemic control and dyslipidaemia. The management of this patient with diabetic retinopathy consists of both medical treatment of the systemic conditions and local laser therapy for the ocular disease.
Because of the probability of macular oedema, fluorescein angiography is usually performed. Treatment with laser photocoagulation, using the focal and grid techniques advocated in the Early Treatment Diabetic Retinopathy Study (ETDRS), is recommended if clinically significant macular oedema is present. Treatment should be accomplished in a timely manner as this eye has very severe non-proliferative diabetic retinopathy. The risks, as Dowler has nicely pointed out, of developing proliferative and possibly high risk proliferative retinopathy, are high in such eyes. Scatter (panretinal) photocoagulation given to eyes without prior focal treatment for macular oedema may cause increased macular oedema and visual acuity decrease that may be difficult to recover. If focal areas of fluorescein leakage can be identified, it would be ideal to treat with focal laser photocoagulation first. When the retinal thickening has responded to the focal treatment with nearly complete resolution, scatter photocoagulation should be considered because he has type 2 diabetes. In addition, his left eye has signs of severe non-proliferative retinopathy, which is a stage that may have increased risk of developing proliferative diabetic retinopathy within the year. I would favour treating his right eye which has the more severe level of diabetic retinopathy at least with early scatter photocoagulation. Assuming a favourable response to treatment of the right eye, I would also consider scatter treatment in his fellow eye. I usually do not wait for high risk proliferative retinopathy to develop. Often, a vitreous haemorrhage may be the presenting sign of such disease, making it much more difficult to apply in the scatter laser. Patients with type 2 diabetes in the ETDRS clearly had a 50% reduction in severe vision loss when early scatter photocoagulation was given at the severe non-proliferative diabetic retinopathy stage.
Series editors: Susan Lightman and Peter McCluskey
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