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.

Maculopathy:

Macular disease has three causes in diabetic
patients—exudative maculopathy, retinal oedema, and
ischaemia. Deterioration of vision in these situations is often
insidious, it can to some extent be prevented 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 very difficult to
treat.
Cataract:

Lens 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

 
The presence of retinopathy must be actively sought by
physicians because, if detected early enough, blindness can be
prevented in many cases by treatment with laser
photocoagulation.

The indications for laser treatment are:

• NVD or NVE; advanced pre-proliferative changes
• clinically significant macular oedema as defined above
• encroachment of hard exudates towards the fovea.
 

Chronic vitreous haemorrhage which precludes a view of
the retina can be treated by vitrectomy and endolaser.
Tractional retinal detachment can be managed by vitrectomy
with the use of heavy liquids and silicone oil. 

Restoration ofvisual acuity can be impressive, but is dependent on the
underlying condition of the retina itself.