Neovascular Glaucoma
An aggressive, sight-threatening form of glaucoma caused by abnormal new blood vessel growth on the iris and drainage angle, most often driven by diabetes, retinal vein occlusion, or other causes of retinal blood flow loss.
Overview
Neovascular glaucoma develops when parts of the retina become starved of oxygen (ischemic), prompting the eye to release a signaling protein called VEGF (vascular endothelial growth factor) that stimulates abnormal new blood vessel growth. These fragile new vessels can grow across the iris and into the drainage angle, physically blocking fluid outflow and, over time, forming a membrane that can scar the angle shut.
It is considered one of the most aggressive and difficult-to-treat forms of glaucoma, and successful management depends on treating the underlying retinal blood flow problem, not just the eye pressure.
Symptoms
- Eye pain and redness, sometimes severe
- Rapidly decreasing vision
- Light sensitivity
- In advanced cases, a very hard, painful eye
How Common Is It?
Neovascular glaucoma develops in a meaningful proportion of eyes with significant retinal ischemia. Estimates vary by underlying cause: it has been reported in roughly a third of eyes with ischemic central retinal vein occlusion, a smaller but significant share of eyes with advanced proliferative diabetic retinopathy, and is also seen with ocular ischemic syndrome (from severe carotid artery disease) and, less commonly, central retinal artery occlusion.
Because it is driven by an underlying retinal or vascular disease process, its overall frequency closely tracks the prevalence and control of diabetes and vascular disease in the population.
Genetics & Risk Factors
Risk is driven by the severity and control of the underlying vascular condition rather than an inherited pattern specific to glaucoma. Poorly controlled diabetes, longer duration of diabetes, uncontrolled blood pressure, and significant carotid artery disease all raise risk.
A history of central retinal vein or artery occlusion in either eye, or known severe diabetic retinopathy, should prompt closer monitoring for early signs of neovascularization.
Ocular Findings on Exam
The earliest and most important exam finding is rubeosis iridis: fine, abnormal new blood vessels visible on the surface of the iris, typically starting at the pupil border and progressing outward.
As the disease advances, gonioscopy may reveal new vessels growing across the drainage angle itself, and eventually a fibrovascular membrane that can physically close the angle and cause very high, difficult-to-control eye pressure.
Testing & Diagnosis
- Careful slit-lamp exam of the iris surface for rubeosis, ideally before pupil dilation
- Gonioscopy to look for new vessels or scarring in the drainage angle
- Dilated fundus exam to assess the retina for ischemia and diabetic or vein-occlusion changes
- Fluorescein angiography or OCT-angiography to map areas of retinal non-perfusion
- Carotid artery imaging (such as carotid Doppler ultrasound) when ocular ischemic syndrome is suspected
- Coordination with a retina specialist, who is typically involved from the outset
Treatment Options
Anti-VEGF Injection
An injectable medication that blocks the VEGF signal driving new vessel growth, often causing rapid regression of iris and angle neovascularization and serving as an important early or adjunctive treatment.
Panretinal Photocoagulation (PRP)
Laser treatment applied to the peripheral, oxygen-starved retina to reduce the ischemic drive for new vessel growth — a cornerstone of long-term control, usually performed by a retina specialist.
Eye Pressure-Lowering Treatment
Aqueous suppressant drops are used to help control pressure, though the angle blockage often makes medical therapy alone insufficient once significant neovascularization has occurred.
Glaucoma Surgery
Tube shunt implants are generally preferred over traditional trabeculectomy, since the abnormal blood vessels increase the risk of bleeding and scarring with trabeculectomy. In severe, blind, and painful eyes that can't be otherwise controlled, cyclophotocoagulation (a laser treatment that reduces fluid production) may be used.
How This Differs From Other Glaucomas
Neovascular glaucoma is unusual because the eye pressure problem is really a downstream consequence of a retinal blood flow emergency, so effective treatment must address the underlying retinal ischemia (with anti-VEGF injection and panretinal laser) alongside, or even before, the eye pressure itself — simply lowering pressure with drops rarely controls the disease on its own.
It also carries a more guarded visual prognosis than most other glaucomas on this page, and standard trabeculectomy surgery is less successful here due to the risk of bleeding and scarring from the abnormal vessels, which is why tube shunt surgery is typically favored when surgery is needed.
Frequently Asked Questions
Why does diabetes cause this?
Poorly controlled or long-standing diabetes can damage the small blood vessels of the retina (diabetic retinopathy), and when enough retina becomes starved of oxygen, the eye releases signals (VEGF) that stimulate abnormal new vessel growth, including on the iris and drainage angle.
Is this an emergency?
Yes. Neovascular glaucoma can progress rapidly and cause severe, sometimes irreversible vision loss and pain, so prompt treatment of both the eye pressure and the underlying retinal ischemia is important.
What is rubeosis iridis?
It's the medical term for abnormal new blood vessels visible on the surface of the iris, usually starting at the pupil border. It's often the first visible sign of neovascular glaucoma and a signal for urgent evaluation.
Can this be prevented?
Good control of diabetes and blood pressure, along with regular dilated eye exams, allows retinal blood vessel damage to be caught and treated (often with laser or anti-VEGF injections) before it progresses to neovascular glaucoma.
See a glaucoma specialist. Dr. Robert Gunzenhauser is Harvard-educated and UCLA fellowship-trained in glaucoma, providing expert diagnosis and treatment for Neovascular Glaucoma at Inland Glaucoma Center in Upland, CA.