Retinopathy

Diabetic retinopathy is the commonest cause of visual loss amongst working age people in the UK. However, it is almost completely preventable with good glycaemic control and regular retinal screening. Diagnosis is usually made on retinal screening. Management is by laser photocoagulation, good glycaemic control and there is also some role for ACE inhibition and possibly fibrate therapy.

Is there any proteinuria?

Proteinuria is an indicator of nephropathy. Nephropathy and retinopathy tend to cosegregate and therefore the presence of one will tend to increase the odds that the patient will develop the other.

What is the creatinine?

Nephropathy and retinopathy tend to cosegregate and therefore the presence of one will tend to increase the odds that the patient will develop the other. 

What is the HbA1c?

HbA1c is an important prognostic factor for development of microvascular complications.

However, if the HbA1c is very high rapid lowering of this may also increase the risk of sudden worsening of any pre-exisitng retinopathy. Over-exuberant corrections of HbA1c (e.g. 3-4% or ~30-40 mmol/mol SI units reduction in a 2-3 month time frame) should be avoided as much as possible and, if they do occur, should prompt additional retinal screening.

Digital retinal photography

Annual digital retinal photographic screening should already have been performed as part of an accredited retinal screening service and indeed will usually be the means by which retinopathy is detected. It should be performed using a mydriatic agent such as tropicamide 1%.

Fluorescein angiography

Fluorescein angiography will often be performed by the ophthalmologist in a case of suspected diabetic retinopathy. It allows more accurate visualisation of the retinal circulation and specifically whether or not there is any capillary 'leakiness' and neovascularisation.

Floerescein is injected intravenously and retinal photos are then obtained using a blue light to excite the fluorescein and a yellow-green filter to acquire the images. The patient should be warned that the urine will turn a yellow-green colour between 12 and 24 hours after the procedure.

Optical coherence tomography

OCT is a relatively new and highly specialised technique for obtaining cross sectional images of the retina, usually for the purpose of assessing macular oedema in cases of diabetic maculopathy. It utilises near-infra red wavelength light to 'scan' the retina and cross-sectional images are then reconstructed digitally.

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