Description,Symptoms, SIGNS – see previous condition
Incidence
Approximately one-third of diabetic patients have diabetic retinopathy (DR); of these, one third have vision-threatening retinopathy. The duration of diabetes is the best predictor of DR. Other factors associated with rapid progression of DR include unstable diabetes, uncontrolled systemic hypertension, hyperlipidaemia, renal disease, pregnancy and indigenous heritage.
Significance
Diabetic retinopathy is a potentially blinding condition. In certain settings, treatments are available which improve the visual prognosis in the vast majority of patients.
Differential Diagnosis
Hypertensive Retinopathy, Central or Branch Retinal Vein Occlusion, Ocular Ischemic Syndrome, Radiation Retinopathy, Systemic Lupus Erythematosis.
Management
Any signs of diabetic retinopathy should be recorded as carefully as possible, ideally with photographs. The patient’s general practitioner and endocrinologist should also be informed.
Ocular tests
The indications for fluorescein angiography include:
- DR close to the macula – to assess the risk of visual loss and determine the appropriate review interval.
- Moderate to severe non-proliferative retinopathy, PDR or macular edema – to assess the degree of retinal ischemia and determine whether laser or other treatment is indicated.
- Recurrent vitreous hemorrhage after laser treatment.
- Visual loss, when clinical examination cannot account for the change.
Review
Diabetic adults should receive an initial dilated and comprehensive eye examination upon diagnosis. If there are no signs of DR and no risk factors for rapid progression are present, the review interval may be one to two years. Otherwise, follow-up is outlined in subsequent chapters.
Advice
Strict glycemic control (often monitored by patient diaries and HbA1c measurement) has been shown to reduce the incidence of diabetic retinopathy. This may entail lifestyle adjustments and medical therapy. When treatment for diabetes mellitus is commenced, altered blood sugar levels alter the osmotic load within the lens, which may alter its refractive index. For this reason, new spectacles should not be prescribed until stable glycemic control has been achieved.
Laser, Surgery
Laser treatment is used in the treatment of PDR and macular edema. Surgical removal of the vitreous (vitrectomy) is also performed in patients with PDR in certain settings.
Figure 1.
Coarsening of capillary network with closure of network between disc & macula; multiple intraretinal microvascular anastomoses; sheathed retinal arterioles; cotton wool spots inferiorly.
Figure 2.
Fluorescein angiogram. Leakage from disc & vessels around the disc; distal complete capillary occlusion.
