Proliferative Diabetic Retinopathy

What’s going on?

The retinal ischaemia caused by the diabetic microvasculopathy results in release of vasoproliferative factors, which causes new blood vessels to form. These new vessels do not have the normal blood-retinal barrier function. They leak therefore and are highly prone to haemorrhage with consequent severe visual loss.

If I examine the patient, what will I find?

There may be fine new blood vessels at the optic disc or elsewhere within the retina. If the new vessels have already ruptured, there will be a vitreous haemorrhage and the view of the fundus will be obscured. If patients have had previous laser treatment, there will be scattered chorioretinal scars (white areas of retinal atrophy with pigmentary proliferation) throughout the retina.

What if I’ve diagnosed it?

Referral should be urgent via letter.

What will the hospital do?

The ischaemic retina that is producing the factors driving the neovascularisation process must be obliterated. Argon laser burns are applied to the peripheral retina destroying retinal tissue. This is known as pan-retinal photocoagulation (PRP). Once the biochemical drive is removed, the new blood vessels will regress.

What do I need to do?

Diabetic and blood pressure control is vital to minimise further progression of diabetic retinopathy.

What to tell the patient

They are at significant risk of visual loss and will require laser treatment and close follow-up at the hospital. Strict diabetic control is vital.

Problems that may arise and how to deal with them

Despite PRP laser treatment, the patient may develop further neovascularisation requiring even more laser treatment, obliterating the remaining peripheral retina (called fill-in PRP).

This sometimes affects peripheral vision enough to prevent the patient being able to drive.