This article is best viewed in a PDF Format
|
|
Non-proliferative diabetic retinopathy (NPDR) consists of a range of clinical signs that confirm the onset of diabetes-associated retinal damage.
Although most patients with NPDR do not require specific ocular treatment, regular review is required to allow prompt detection and/or treatment of proliferative diabetic retinopathy (PDR), thought to result from retinal ischaemia, or diabetic macular oedema (DME), related to leaking retinal vessels.
Symptoms
NPDR is usually asymptomatic.
Signs
The International Clinical Diabetic Retinopathy Disease Severity Scale grades NPDR as follows (see Diabetes - introduction to retinopathy, for explanation of terms):
No apparent DR: no abnormalities visible
Mild NPDR: microaneurysms only
Moderate NPDR: more than 'mild', but less than 'severe'
Severe NPDR: any of the following ('the 4:2:1 rule'): 20 or more intraretinal haemor-rhages in all four quadrants venous beading in two or more quadrants or prominent IRMAs in at least one quadrant.
Prevalence
NPDR is present in up to 20 per cent of patients at the time of diagnosis of Type 2 diabetes, and develops in up to 90 per cent of patients over the next 20 to 30 years (although estimates vary).
Significance
The severity of NPDR reflects the risk of progression to PDR over subsequent years. For example, approximately 8 per cent of patients with moderate NPDR progress to PDR each year. This may increase to approximately 17 per cent a year with severe NPDR these patients may benefit from laser treatment.
See also
Diabetes - Introduction to retinopathy Diabetes - Proliferative retinopathy Diabetes - Macular oedema.
Management
Ocular tests, imaging investigations
Intravenous fluorescein angiography informs decision-making regarding appropriate review intervals and indications for laser treatment. It is also valuable in differentiating severe NPDR from PDR: fluorescein does not leak from IRMAs, but leaks profusely from areas of neovascularisation. Capillary non-perfusion is confirmed in areas of the retina containing cotton-wool spots on clinical examination.
Advice
The physician overseeing the management of the patient's diabetes must be notified of the presence of diabetic retinopathy, since it strongly suggests the presence of microvascular disease in other organs (particularly the kidneys).
The Diabetes Control and Complications Trial (DCCT) and UK Prospective Diabetes Study (UKPDS) established the value of intensive glycaemic control in reducing the risk of onset and progression of diabetic retinopathy and other microvascular complications of diabetes.
Other measures - including physical exercise, smoking cessation and management of hypertension and dyslipidaemia - may delay or prevent diabetes-related complications (such as PDR, renal failure, myocardial infarction and stroke).
Review and Laser
Review at six-month intervals is appropriate for mild NPDR, and more frequently for moderate or severe NPDR. If diabetic retinopathy threatens to affect central vision, a decision needs to be made whether laser or other treatment is indicated.