A type of secondary glaucoma, neovascular glaucoma is the result of the angle of the eye being closed off by new blood vessels. This “angle” is that which is located between the iris, or colored part of the eye, and the cornea, or the clear protective shield that makes up the front eye. If left untreated, the condition can cause additional damage and lead to severe chronic pain, so it is important to discuss any new developments or eye concerns with your doctor.
What Is Neovascular Glaucoma?
Neovascularization of the anterior peripheral synechiae and trabecular meshwork. (Image Source: InTechOpen)
If the eye system is healthy, the iris and drainage angle where the meshwork lies in the corner of the eye have normal, healthy vessels functioning in them. However, in an eye with neovascular glaucoma, abnormal vessels may begin growing in these areas. The abnormal vessels alter the function of the spongy tissue in the area, often causing leaking and inflammation at the corner of the eye.
If the condition progresses, the new blood vessels may actually grow over and close off the drainage angle. This process, which involves scarring and narrowing, increases eye pressure because the fluid cannot be released from the eye effectively. In these cases, the eye generally becomes very inflamed and painful. Vision is usually altered as well.
Symptoms of Neovascular Glaucoma
The symptoms of this type of glaucoma depend on the severity of the blockage. Some individuals my experience vision loss, while others maintain their good vision. Retinal diseases like this one are generally found after a patient has experienced vision loss and begins seeking care. Others may be diagnosed during a routine annual examination.
The condition typically occurs in stages. Each stage has varying degrees of potential impact. While some my experience some minor annoyance, others undergo severe pain, redness, and vision loss. The common stages of the condition include:
- Rubsosis iridis. Symptoms in this stage are minor to nonexistent and may include mild redness, pain, and photophobia.
- Secondary open-angle glaucoma. This is the second stage of the condition. Symptoms in this stage may include redness, pain, light sensitivity, and headache.
- Secondary angle closure glaucoma. This is the most severe form of the condition. If you are in this stage, you will likely experience severe pain, headache, photophobia, and nausea or vomiting.
It is common for the pupils to be poorly reactive or even distorted or dilated in each of the stages.
Late rubeosis with mid-peripheral neovascularization (Image Source: InTechOpen)
Causes of Neovascular Glaucoma
The new blood vessel growth causes pressure to increase in the eye, leading to the pain and inflammation characteristic of the condition. There are several different factors that affect this new blood vessel growth.
If retinal vein blockage or diabetic eye disease is the issue, the retina does not have the right amount of oxygen moving to it. The retina naturally begins releasing chemicals to counter the issue, including vascular endothelial growth factor (VEGF).
The newly formed vessels could in reality bring more oxygen to the sick retina, but since the retina is diseased, the new vessels are malformed and leaky. In some cases, the malformation is so severe that it causes bleeding of the abnormal vessels, which can cause hemorrhaging.
As the retina continues to release VEGF into the eye, the growth hormone migrates to the front of the eye. This migration causes new blood vessel formation on the iris as well as the drainage angle.
Risk Factors
The condition is most common in older individuals. Likewise, several preexisting factors place you at a higher risk for contracting the condition, including:
- Retinal ischemia;
- Irradiation;
- Tumors;
- Ocular inflammatory disease;
- Surgery;
- Vascular disorders;
- Diabetes.
Treatments for Neovascular Glaucoma
Treatment of the condition is very important. It can also be quite effective, particularly if the condition is caught in its earlier stages. As such, treatment is generally differentiated by stage.
Early Treatment
The condition is considered in its early stage if there is some new blood vessel develop in the drainage angle, partially obstructing the meshwork and increasing internal pressure. In this stage one of the most important therapies includes atropine applied topically at a 1% concentration to reduce congestion of the eye. This regimen also includes the application of tropical steroids to decrease inflammation. Depending on the current state of your eyes and vision, you doctor may suggest additional treatment options as well.
Advanced Treatment
This stage of the condition is typically denoted by the closure of the angle. In this stage, your doctor will likely suggest panretinal photocoagulation (PRP) or cryophototherapy to prevent further closure of the drainage angle. In many cases, surgery is also required in advanced stage neovascular glaucoma. To prepare for surgery, your doctor will prescribe a regimen of topical atropine and steroids to control inflammation and pressure.
End Treatment
You are considered in end-stage of the condition if the angle has been completely closed, and you have no remaining useful vision. In this case, the primary goal is pain management. Therapy typically continues with atropine and steroids applied topically. Likewise, if decomposition of the cornea occurs, you may need a bandage contact lens. In rare cases, cyclodestructive procedures are used to provide symptom relief if other therapies have failed.
Prevention
At any rate, prevention is the most effective treatment. This measure of treatment aims at preventing any of the most common causes of the condition, including vein blockage and diabetic retinopathy. Other risk factors to note include high blood pressure and heart disease.
Effectively controlling blood pressure is an important measure of treatment, so you should work with your ophthalmologist as well as your primary care team to meet this goal. Likewise, keeping blood sugar levels in check is important to prevent diabetic retinopathy. Also be sure to have a yearly dilated exam under the age of 65 and a comprehensive eye exam every 1 to 2 years after 65.
Final Thoughts
While neovascular glaucoma is a progressive disease, it can typically be well-treated if the condition is caught early and if necessary treatment measures are taken. If caught in its early stages, the condition can be managed to reduce vision loss and discomfort. Several factors do complicate the issue and its treatment, however, so it is important to work closely with your care providers to achieve the best results.
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