Vision is a key sense that many of us rely on each day to navigate our busy lives. Glaucoma is a progressive eye disease that can damage the optic nerve and can ultimately result in gradual vision loss.
We asked Sarwat Salim, MD, FACS, Director of the Glaucoma and Cataract Service in Ophthalmology at Tufts Medical Center, to provide information about the symptoms, risk factors and prevention of glaucoma. Dr. Salim is also a Professor of Ophthalmology at Tufts University School of Medicine and Vice Chair of Clinical and Academic Affairs at New England Eye Center.
What is glaucoma?
Glaucoma is a progressive eye disease that can damage the optic nerve. The optic nerve is responsible for transmitting information from our eyes to the brain to form an image. Most often, optic nerve damage is caused by increased pressure in the eye, known as intraocular pressure. The front part of the eye fills with a clear fluid called aqueous humor. This process of fluid formation and drainage is a continuous cycle. Anything that slows or blocks the flow of this fluid will cause elevated intraocular pressure.
Glaucoma can result in gradual loss of vision. It is the second most common cause of blindness in the United States and is the leading cause of irreversible blindness in African Americans. At present, approximately 3 million people are afflicted with glaucoma in the United States and about 50% of these individuals may not even know that they have the disease because people don't always present with symptoms.
What are the symptoms of glaucoma?
There are many different types of glaucoma. The two major categories are primary open-angle glaucoma and closed-angle glaucoma. There are also secondary glaucoma, congenital/childhood glaucoma, among other types. In the United States, the most common type of glaucoma is primary open-angle glaucoma.
Open-angle glaucoma is usually painless and has no symptoms because the increase in intraocular pressure happens slowly over time. Most people with open-angle glaucoma do not experience symptoms. Early damage results in loss of peripheral vision.
Closed-angle glaucoma presents with sudden and severe pain in the eye and high intraocular pressure. Patients often experience decreased vision, rainbow-like halos around lights, nausea, or vomiting. Closed-angle glaucoma is considered an ocular emergency and must be addressed immediately.
Secondary glaucoma occurs due to use of corticosteroids, eye injury, diabetes, uveitis, or other eye diseases. Symptoms depend on the underlying problem. Secondary glaucoma may be either open-angle or closed-angle depending on the cause.
Congenital glaucoma occurs in infants and young children. This tends to run in families and is often due to developmental abnormality of the eye, specifically the drainage angle. Babies with glaucoma are often noted to have increased tearing, light sensitivity, and cloudiness of the cornea. Because their eyes are still developing, elevated intraocular pressure causes enlargement of the eye.
What are the risk factors?
The most important and well-studied risk factor is elevated intraocular pressure. Other risk factors include advancing age, family history of glaucoma, African or Latino descent, severe myopia or nearsightedness, and systemic diseases such as hypertension (high blood pressure) or diabetes. Physical injury to the eye can also cause glaucoma. Also, long-term use of steroids (either drops or pills) can also increase intraocular pressure.
How do you diagnose and prevent glaucoma?
The best way to diagnose and prevent glaucoma is by having a complete eye exam. The American Academy of Ophthalmology recommends a complete eye exam by the age of 40. However, if you have other risk factors, you should have a complete eye exam sooner than age 40. Important elements of the examination include visual acuity test, tonometry to measure intraocular pressure, gonioscopy to assess if the drainage angle is open or closed, slit lamp examination to assess the anterior segment of the eye, use of special lenses to examine the optic nerve and posterior segment of the eye, and visual field test to assess the loss of peripheral or central vision.
What treatments can be helpful?
The goal of treatment is to reduce intraocular pressure.
- Open-angle glaucoma is treated with eye drops to reduce the formation of fluid in the eye or increase its outflow from the eye. Sometimes, certain eye drops may not be suitable for a given individual, so systemic medications can be prescribed. Therefore, a thorough medical history is necessary to avoid any side effects.
- Closed-angle glaucoma is an attack and is considered a medical emergency. If left untreated, one can become blind in a few days. We use medical therapy to lower intraocular pressure followed by a laser treatment called iridotomy. This procedure makes an opening in the iris, and this new channel relieves the attack. To help prevent an attack in the other eye, iridotomy is prophylactically done in the other eye as well.
- Secondary glaucoma is treated by identifying the underlying cause and providing a specific treatment plan.
- Congenital glaucoma is almost always treated with surgery with medical therapy playing an adjunctive role.
What if medical therapies fail?
If medical therapies fail, laser can be performed to open the channels where the fluid flows out. When both medical therapy and laser treatment don’t work, incisional surgery in the operating room is necessary. Commonly performed surgical procedures include trabeculectomy and glaucoma drainage devices. While effective in lowering intraocular pressure and slowing progression of disease, each is associated with a unique set of potential complications.
Individualized treatment is very important because depending on type of glaucoma, severity of glaucoma, patient’s age or other comorbidities, it can affect the outcome. It is important to have a detailed conversation with your physician regarding the risks, benefits, and alternatives of any surgical intervention. Unfortunately, there is no cure for glaucoma, but with ongoing surveillance and monitoring it can be controlled.