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Proliferative Diabetic Retinopathy (PDR)

Advanced diabetic eye disease where fragile new retinal blood vessels grow, bleed, scar, and can lead to severe vision loss.

9 min read

PDR is the advanced stage of diabetic retinopathy in which poor retinal blood flow stimulates abnormal new blood vessel growth on the retinal surface or optic nerve. These vessels are fragile and can bleed, form scar tissue, and pull on the retina. Major complications include vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma. Prompt treatment aims to prevent these complications before vision is severely damaged.

Proliferative diabetic retinopathy retina diagram showing ischemia-driven neovascularization, fragile bleeding vessels, traction scar tissue, and PRP laser treatment
Proliferative diabetic retinopathy grows fragile new vessels that can bleed and create traction scar tissue.

Key Takeaways

  • PDR is advanced diabetic retinopathy, driven by poor retinal blood flow
  • Fragile new vessels grow on the retina or optic nerve, then bleed and scar easily
  • Vision can drop suddenly from vitreous hemorrhage or more slowly from traction and macular damage
  • Laser and anti-VEGF injections can prevent blindness, especially before major bleeding or detachment
  • Major complications include vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma
  • Prompt treatment matters; this is not the stage to miss appointments

What Happens in PDR

Why New Vessels Grow

When the retina becomes severely oxygen-deprived (ischemic):

  • Retinal cells release growth factors (especially VEGF)
  • These factors stimulate new blood vessel growth
  • The body is trying to resupply blood to ischemic areas
  • But these new vessels are abnormal and cause problems

The Problem with Neovascularization

The new blood vessels are fragile and poorly formed:

  • Thin walls prone to leaking and bleeding
  • Grow into the vitreous cavity (should stay in retina)
  • Cause bleeding into the vitreous (vitreous hemorrhage)
  • Develop scar tissue that contracts
  • Pull on the retina (tractional retinal detachment)
  • Can grow on the iris (neovascular glaucoma)

Types of Neovascularization

Neovascularization of the Disc (NVD)

  • New vessels growing on or near the optic nerve head
  • High-risk feature
  • Greater risk of severe vision loss

Neovascularization Elsewhere (NVE)

  • New vessels growing on the retina away from the disc
  • Also dangerous but slightly less than NVD
  • Can still cause severe complications

Neovascularization of the Iris (NVI)

  • New vessels on the iris
  • Can block the drainage angle
  • Causes neovascular glaucoma
  • Requires urgent treatment

High-Risk Characteristics

Symptoms

When New Vessels Haven't Bled

  • May have no symptoms
  • Vision may still be good
  • Detected on routine exam

When Bleeding Occurs (Vitreous Hemorrhage)

  • Sudden onset of floaters
  • Shower of floaters
  • Cobweb or veil in vision
  • Vision may become very cloudy or red
  • May see only light (if dense hemorrhage)

With Retinal Detachment

Complications

Vitreous Hemorrhage

What Happens:

  • Fragile new vessels bleed into the vitreous cavity
  • Blood clouds the normally clear vitreous
  • Light can't reach the retina

Symptoms:

  • Sudden floaters, often a shower of them
  • Cloudy or hazy vision
  • May see only light

Treatment:

  • May clear on its own (over weeks to months)
  • Anti-VEGF injections speed clearing
  • Vitrectomy surgery if doesn't clear

Tractional Retinal Detachment

What Happens:

  • Scar tissue forms along new vessels
  • Scar tissue contracts
  • Pulls the retina away from its normal position

Types:

  • Extramacular: doesn't involve central vision-may observe
  • Macular: involves macula-needs surgery
  • Combined tractional-rhegmatogenous: needs urgent surgery

Treatment:

  • Vitrectomy surgery to remove scar tissue and reattach retina

Neovascular Glaucoma

Diagnosis

Clinical Examination

  • Dilated fundus exam
  • Look for new vessels on disc and retina
  • Assess vitreous for hemorrhage
  • Check for retinal detachment
  • Examine iris for neovascularization
  • Check eye pressure

Imaging

Fluorescein Angiography:

  • Shows leaking new vessels
  • Defines extent of ischemia
  • Essential for treatment planning

OCT:

  • Detects macular edema
  • Shows vitreoretinal interface
  • May show early tractional changes

Ultrasound:

  • If vitreous hemorrhage blocks view
  • Assesses whether retina is attached

Treatment

Anti-VEGF Injections

Anti-VEGF injections are often first-line for PDR:

  • Aflibercept (Eylea)
  • Ranibizumab (Lucentis)
  • Bevacizumab (Avastin, off-label)

Benefits:

  • Rapid regression of new vessels
  • Help clear vitreous hemorrhage
  • Reduce macular edema if present
  • Can be done immediately

Limitations:

  • Effect is temporary (needs repeat injections)
  • May need laser as well

Panretinal Photocoagulation (PRP)

The Mainstay of Treatment:

  • Laser applied to peripheral retina
  • 1,000-2,000 or more laser spots
  • Destroys ischemic retina
  • Reduces oxygen demand
  • Reduces VEGF production
  • Causes new vessels to regress

Side Effects:

  • Reduced peripheral vision
  • Reduced night vision
  • Usually well tolerated given the alternative (blindness)

Effectiveness:

  • Reduces severe vision loss by ~50%
  • Proven benefit in landmark clinical trials
  • Remains essential treatment

Vitrectomy Surgery

Indications:

  • Non-clearing vitreous hemorrhage
  • Tractional retinal detachment involving or threatening the macula
  • Combined tractional-rhegmatogenous detachment

What's Done:

  • Small instruments enter the eye
  • Vitreous gel is removed
  • Blood is cleared
  • Scar tissue is removed
  • Retina is reattached if needed
  • Laser is applied during surgery
  • Gas or silicone oil may be placed

Outcomes:

  • Many patients improve, but visual recovery depends on retinal damage and timing
  • Better outcomes with earlier surgery
  • Some patients need multiple surgeries

Treatment Approach

Modern management often combines:

  1. Anti-VEGF injection first (quick effect)
  2. PRP laser (longer-lasting prevention)
  3. Vitrectomy if complications occur
  4. Ongoing treatment of macular edema

Prognosis

With Treatment

  • Severe vision loss reduced by ~50% or more
  • Many patients maintain useful vision
  • Better outcomes with earlier treatment
  • Better outcomes with good systemic control

Without Treatment

  • Approximately 50% develop severe vision loss within 2 years
  • PDR is a leading cause of blindness

Factors Affecting Outcome

  • Severity at diagnosis
  • Presence of complications
  • Response to treatment
  • Systemic control (blood sugar, blood pressure)
  • Adherence to follow-up

Living with PDR

What You Can Do

Systemic Control:

  • Blood sugar management remains important
  • Blood pressure control - both diabetes and high blood pressure damage retinal vessels, and understanding how each contributes to your eye changes can help guide management
  • These affect progression and treatment response

Adhere to Treatment:

  • Keep all appointments
  • Get scheduled injections
  • Complete laser treatment
  • Don't delay surgery if recommended

Know Warning Signs:

  • New floaters (may indicate bleeding)
  • Sudden vision loss
  • Shadow or curtain over vision
  • Seek immediate care for these symptoms

Emotional Support

  • PDR diagnosis can be frightening
  • Vision loss can change work, driving, reading, and independence
  • Support groups can help
  • Counseling may be beneficial
  • Low vision services if needed

Prevention

Preventing PDR (If You Have NPDR)

  • Excellent blood sugar control
  • Blood pressure control
  • Regular eye exams
  • Treat severe NPDR before it progresses

For Those with Diabetes

  • Annual dilated eye exams
  • Work with your diabetes care team
  • Don't smoke
  • Control all risk factors

Frequently Asked Questions

Will I go blind?

With timely treatment, systemic control, and reliable follow-up, many patients avoid severe vision loss. However, PDR is serious and requires prompt treatment. The key is getting treatment early and following through with all recommended care.

Is laser treatment painful?

You may feel some discomfort during PRP laser treatment. Anesthetic drops and sometimes injections are used. Discomfort is usually tolerable and temporary. The treatment is done to prevent blindness.

How many treatments will I need?

This varies. You may need multiple laser sessions to complete PRP. You may need ongoing anti-VEGF injections, especially if you have macular edema. Some patients need treatment for years.

Can the new blood vessels go away?

Yes. Anti-VEGF injections can cause rapid regression of new vessels. Laser treatment can provide more durable reduction in ischemic drive, but recurrence or progression can still occur if the underlying ischemia persists.

What if my eye bleeds?

Vitreous hemorrhage (bleeding) is common in PDR. It often clears on its own over weeks to months. Anti-VEGF injections can speed clearing. Surgery (vitrectomy) can remove blood if it doesn't clear. Many patients improve, but recovery depends on macular ischemia, traction, baseline vision, and timing.

Can I still drive?

This depends on your vision level. Some patients with PDR maintain excellent vision; others have significant loss. You'll be evaluated to determine if you meet legal requirements for driving. The goal of treatment is to preserve as much vision as possible.

References

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