April 28, 2003
ABC of diabetes : Clinical review (2)
BMJ 2003;326:924-926 ( 26 April )
Blindness in diabetic patients
vision threatening retinopathy is usually due mainly to neovascularisation in type 1 diabetes and maculopathy in type 2 diabetes. In North America, 3.6% of patients with type 1 diabetes and 1.6% of patients with type 2 diabetes are legally blind. In England and Wales, about 1000 diabetic patients are registered as blind or partially sighted each year, with diabetic retinopathy being the commonest cause of blindness in the working population.
Vitreous haemorrhage occurs suddenly and painlessly. The blood usually clears over the following weeks, but the underlying proliferative retinopathy causes repeated haemorrhages and progressive visual loss in most cases if it is not treated. Retinal detachment resulting from contracting fibrous bonds sometimes causes blindness.
MaculopathyMacular disease has three causes in diabetic patients: exudative maculopathy, retinal oedema, and ischaemia. Deterioration of vision in these situations is often insidious. Deterioration can be prevented to some extent by appropriate laser treatment, but once vision has been lost it cannot be restored. Ischaemic maculopathy due to loss of perifoveal capillaries may cause severe visual loss and is difficult to treat.
CataractLens opacities or cataract develop earlier in diabetic patients and often progress more rapidly.
Primary open angle glaucoma has an increased prevalence in diabetic patients compared with the general population.
Prevention of blindness
Physicians must actively seek retinopathy in diabetic patients as laser photocoagulation can often prevent blindness if the condition is detected early enough. The indications for laser treatment are:
1-New vessels on disc or elsewhere in retina; advanced pre-proliferative changes 2- Clinically significant macular oedema (see above) 3- Encroachment of hard exudates on the fovea.
Chronic vitreous haemorrhage that precludes a view of the retina can be treated by vitrectomy and endolaser. Tractional retinal detachment can be managed by vitrectomy. Restoration of visual acuity can be impressive, but it is dependent on the underlying condition of the retina.
Posted by mehdi khanlari at April 28, 2003 05:47 AM