Neovascular Glaucoma (NVG)

How neovascular glaucoma develops

1. Retinal ischemia: a lack of blood flow to the retina from diabetes, a vein or artery blockage, or carotid disease
2. VEGF release: the starved retina releases vascular endothelial growth factor
3. New vessels: abnormal vessels grow on the iris surface (rubeosis iridis) and into the drainage angle
4. Open-angle stage: a fibrovascular membrane covers the drainage meshwork, raising pressure
5. Closed-angle stage: the membrane contracts, pulling the iris over the angle and sealing it shut, causing very high pressure

Causes

• proliferative diabetic retinopathy: one of the most common causes
• central retinal vein occlusion: especially the ischemic type. NVG classically develops around 3 months after the occlusion ("90-day glaucoma"), though timing varies
• ocular ischemic syndrome from severe carotid artery stenosis
• central retinal artery occlusion
• less common: long-standing retinal detachment, eye tumors, chronic inflammation, radiation

Symptoms

Early neovascularization may cause no symptoms. As pressure rises:

• eye pain and aching around the eye or brow
• redness
• blurred vision and halos around lights (from corneal swelling)
• headache, nausea or vomiting with very high pressure
• light sensitivity
• reduced vision from the underlying retinal disease

Diagnosis

An ophthalmologist will:

• measure eye pressure, often very high (sometimes above 40 to 60 mmHg)
• examine the iris with a slit lamp before dilating drops to spot fine new vessels at the pupil edge
• perform gonioscopy, using a special lens to view the drainage angle
• dilate the pupil and examine the retina
• use imaging: fluorescein angiography and OCT angiography to map areas of poor blood flow
• check for systemic causes: blood sugar control, blood pressure, and carotid ultrasound if ocular ischemic syndrome is suspected

Treatment

Treatment has two goals: stop the drive for new vessels and control eye pressure.

Treat the ischemic retina

• anti-VEGF injections into the eye (bevacizumab, ranibizumab, aflibercept) quickly shrink new vessels, often within days
• panretinal photocoagulation (PRP): laser treatment to the peripheral retina reduces oxygen demand and VEGF production for long-term control

Lower eye pressure

• eye drops: beta blockers, alpha agonists, carbonic anhydrase inhibitors
• oral acetazolamide for very high pressure
• steroid and dilating drops (atropine) to reduce inflammation and pain
• prostaglandin drops may be less effective in active inflammation

Surgery

When medicines are not enough:

• glaucoma drainage devices (tube shunts)
• trabeculectomy with antiscarring medicine, often less successful in NVG
• cyclophotocoagulation: laser to reduce fluid production, especially in eyes with poor visual potential

Comfort care

In eyes with no remaining useful vision, the aim is to relieve pain with drops and, rarely, procedures to reduce fluid production or remove the eye.

Outlook

The visual outcome depends on how early it is caught and how much the retina was damaged by the underlying disease. Many eyes with established NVG lose significant vision. Early detection of new vessels, before the angle closes, offers the best chance of preserving sight.

Prevention

• tight control of blood sugar, blood pressure and cholesterol in diabetes
• yearly dilated eye exams with diabetes
• close follow-up for at least several months after a retinal vein occlusion
• prompt treatment of proliferative diabetic retinopathy

Frequently asked questions

What is neovascular glaucoma?

It is a severe secondary glaucoma in which abnormal new blood vessels grow on the iris and block the eye's drainage channels, causing very high eye pressure. It results from a lack of blood flow to the retina.

What causes neovascular glaucoma?

The most common causes are proliferative diabetic retinopathy and central retinal vein occlusion. Severe carotid artery disease (ocular ischemic syndrome) and retinal artery occlusion are other causes.

What are the symptoms of neovascular glaucoma?

Symptoms include a painful red eye, blurred vision, halos around lights, headache and sometimes nausea. Early stages can be silent, which is why regular eye exams for people with diabetes or a recent vein occlusion matter.

How is neovascular glaucoma treated?

Anti-VEGF injections and laser treatment to the retina stop new vessel growth. Pressure-lowering drops, oral medicine and often surgery, such as a tube shunt or laser to reduce fluid production, control eye pressure.

Can vision be restored after neovascular glaucoma?

Vision lost from optic nerve damage cannot be restored. Prompt treatment can preserve remaining vision and relieve pain. Outcomes depend on how early treatment begins and the health of the retina.