Proliferative Diabetic Retinopathy

Proliferative Diabetic Retinopathy (PDR): The Imminent Danger to Vision

Proliferative diabetic retinopathy (PDR) is the most advanced and aggressive stage of diabetic retinopathy, where damage from diabetes triggers the growth of abnormal new blood vessels (neovessels) in the retina and vitreous. These vessels are fragile, defective, and prone to bleeding, leading to devastating complications that can cause irreversible vision loss within weeks or months.

Why is PDR So Dangerous?

1. Neovascularization: Vessels That Destroy Instead of Help

Retinal ischemia (lack of oxygen) releases chemical signals (such as VEGF) that stimulate the growth of neovessels.

These vessels do not nourish the retina, but rather:

Bleed into the vitreous (vitreous hemorrhage).

They form fibrous membranes that pull on and detach the retina.

They obstruct aqueous humor drainage, causing neovascular glaucoma.

2. Catastrophic Complications

Vitreous Hemorrhage

Tractional Retinal Detachment

Neovascular Glaucoma

3. Risk of Blindness

Up to 50% of patients with untreated PDR lose useful vision within 5 years (Diabetes Care).

Neovascular glaucoma has a 60% blindness rate despite treatment (Ophthalmology).

How is it Diagnosed?

Fundus with pupillary dilation:

New vessels in the retina, optic disc, or iris.

Vitreous or preretinal hemorrhages ("boat spots").

Fluorescein angiography:

Maps areas of extensive ischemia (dark areas without circulation).

OCT and ocular ultrasound:

Useful if there is dense vitreous hemorrhage that obscures the retina.

Treatment: A Race Against Time

The goal is to destroy the neovessels and reduce ischemia to prevent further damage.

1. Laser Pan Retinal Photocoagulation (PRP)

What it does: Burns peripheral ischemic areas to reduce VEGF production.

Side effects:

Loss of peripheral and night vision.

Pain during the procedure.

Efficacy: Reduces the risk of blindness by 50%.

2. Intravitreal Anti-VEGF Injections

Drugs: Aflibercept (Eylea®), Ranibizumab (Lucentis®).

Benefits:

Reduces neovessels.

Improves associated macular edema.

Limitations:

Requires initial monthly applications.

Does not eliminate background ischemia.

3. Vitrectomy

Indications:

Vitreous hemorrhage that does not resorb within 3-6 months.

Tractional retinal detachment.

Risks: Early cataract, rebleeding postoperatively.

⚠️ Factors That Make Control Difficult

❌ Poorly controlled diabetes (HbA1c >9%): Neovascularization recurs rapidly.

❌ Delayed diagnosis: PDR is already advanced when symptoms appear.

❌ Lack of treatment adherence: Injections must be continuous.

❌ Unmanaged systemic diseases: Hypertension, kidney failure.

Critical Message for Patients

"PDR is a silent emergency": By the time symptoms appear, there is already severe damage.

"Lasers and injections save vision, but they do not restore it": The later treatment is given, the less vision can be preserved.

"Surgery is a last resort": Vitrectomy is complex and does not always restore lost vision.