Open Angle Glaucoma
Open-angle glaucoma is a silent eye condition that can steal your vision without warning. Understanding this disease and getting early treatment can help protect your sight for years to come.
Table of contents
- What is Open-Angle Glaucoma?
- Symptoms and Vision Changes
- What Causes Open-Angle Glaucoma?
- Who Is at Risk?
- How Is It Diagnosed?
- Treatment Options
- Living With Open-Angle Glaucoma
What is Open-Angle Glaucoma?
Open-angle glaucoma is the most common type of glaucoma, which is a group of eye diseases that damage the optic nerve (the nerve that carries visual information from your eye to your brain)[1]. It accounts for more than 90 percent of glaucoma cases in the United States[6].
In open-angle glaucoma, your eye’s drainage system starts to back up, usually so slowly that you don’t notice[1]. This prevents fluid from draining normally from your eye. As the fluid builds up, pressure inside your eye increases. This condition is called ocular hypertension (high pressure inside the eye)[1].
The increased pressure damages your optic nerve over time. This damage is irreversible and leads to gradual vision loss[1]. Without treatment, open-angle glaucoma can progress to blindness[1].
The condition is called “open-angle” because the drainage angle where fluid should exit the eye appears to be open and looks normal. The problem occurs deeper within the drainage system, in a spongy tissue called the trabecular meshwork[1]. It’s similar to a clogged pipe below a sink drain — the drain opening looks fine, but there’s a blockage further down[4].
Open-angle glaucoma is often called the “silent thief of sight” because it rarely causes symptoms in the early stages[7]. Approximately 3 million Americans have glaucoma, but about half are unaware they have the disease[6].
Symptoms and Vision Changes
Most people don’t notice symptoms until they have significant vision loss[1]. The disease usually affects both eyes, but it’s typically more advanced in one eye. This makes it harder to notice, because the stronger eye compensates for the weaker one[1].
Vision loss from open-angle glaucoma starts at the edges of your visual field (your peripheral vision, or side vision) and slowly closes in toward the center[1]. This pattern of vision loss is often imperceptible because only in moderate to late stages do these side vision deficits become more noticeable[7].
Signs you might notice include:
- Missing a stair when walking downstairs
- Missing some of the letters in a word you’re reading
- Having trouble reading road signs while driving
- Having trouble seeing contrast in low light[1]
During an eye examination, your eye care provider may notice specific visual field defects, such as:
- Nasal step defect: A blind spot on the side of your visual field close to your nose
- Arcuate scotoma: An arc-shaped blind spot on the top or bottom of your visual field
- Paracentral scotoma: A small, roundish blind spot just off the center of your visual field
- Temporal wedge defect: A wedge-shaped dark area on the temple side of your visual field[1]
As open-angle glaucoma advances, it leads to gradually worsening tunnel vision[1]. In advanced stages, central vision can be affected, potentially leading to blindness[2].
Unlike some other forms of glaucoma, open-angle glaucoma typically doesn’t cause eye pain, redness, or other noticeable symptoms[7]. Most patients with primary open-angle glaucoma do not experience symptoms from high eye pressure because the pressure increases gradually over time[7].
What Causes Open-Angle Glaucoma?
Your eyes have a built-in drainage system for the fluid they produce. This clear fluid, called aqueous humor, is produced by a structure called the ciliary body. The fluid passes through the pupil and drains through the trabecular meshwork[6].
Glaucoma happens when something interferes with this drainage system and the fluid builds up inside. As this happens, it raises the pressure inside your eye. If your eye has elevated pressure for a long period of time, it can damage your optic nerve[1].
In open-angle glaucoma, the drainage angle appears to be open and functioning normally, but resistance seems to build up within it. Experts believe the issue is in the trabecular meshwork[1]. In primary open-angle glaucoma, there is an abnormality of material in the part of the trabecular meshwork immediately adjacent to the drainage canal[14].
Importantly, elevated eye pressure is a major risk factor but not a diagnostic factor for open-angle glaucoma[6]. About 15 percent of patients with characteristic glaucomatous nerve damage have consistently normal eye pressure. These patients have normal-pressure glaucoma[6]. Conversely, more than two-thirds of patients with elevated eye pressure do not lose visual field or develop optic nerve damage[6]. These patients are referred to as “glaucoma suspects.”
The exact cause of why the drainage system malfunctions in most cases of open-angle glaucoma isn’t clear[5]. Known causative risk factors include elevated eye pressure and insults to the eye, including trauma, inflammation, and steroid therapy[6].
Who Is at Risk?
Your chances of developing open-angle glaucoma increase based on several factors:
Age: Open-angle glaucoma mostly affects people over age 50, and your risk rises as you get older[5]. Patients at increased risk include whites older than 65 years[6].
Race and ethnicity: African-Americans and Hispanics get open-angle glaucoma more often than whites[5]. Black race increases the prevalence of glaucoma by a factor of four[6]. In Black people, glaucoma is more severe, develops at an earlier age (those older than 40 years are at increased risk), and blindness is 6 to 8 times more likely[14]. Glaucoma is the leading cause of legal blindness among blacks in the United States[6].
Family history: You’re more likely to get open-angle glaucoma if other family members have it[5]. A positive family history is a significant risk factor[14].
Medical conditions: Certain health conditions raise your odds, including:
Eye characteristics: Having a thin cornea (the clear front surface of the eye) is a risk factor[5]. Thinner central corneal thickness is associated with increased risk[14].
Steroid use: While steroid therapy of any kind may contribute to elevated eye pressure, topical eye and periocular (around the eye) steroids seem most likely to increase pressure[6].
How Is It Diagnosed?
Open-angle glaucoma usually is discovered during an adult eye evaluation performed for other indications[6]. An eye care professional will review your medical history and perform a comprehensive eye exam[3].
Several tests may be performed to diagnose open-angle glaucoma:
Measuring intraocular pressure (also called tonometry): This test measures the pressure inside your eye[3]. However, routine measurement of eye pressure by primary care physicians to screen patients for glaucoma is not recommended[6].
Testing for optic nerve damage: This involves a dilated eye exam where the doctor examines your optic nerve, and imaging tests that can detect characteristic changes[3]. Findings include increased cup-to-disk ratio (particularly an increasing ratio over time), thinning of the neurosensory rim, pitting or notching of the rim, and nerve fiber layer hemorrhages[14].
Checking for areas of vision loss (visual field test): Formal visual field testing, also called perimetry, is a mainstay of glaucoma diagnosis and management[6]. This test detects blind spots in your peripheral and central vision.
Measuring corneal thickness (an exam called pachymetry): This test measures how thick your cornea is[3].
Inspecting the drainage angle (a procedure called gonioscopy): This examination allows the doctor to see whether the angle where fluid drains from your eye is open or closed[3]. In open-angle glaucoma, the angle is unobstructed and open[14].
Final diagnosis and treatment typically occur in collaboration with ophthalmologists and optometrists[6]. As a newly diagnosed person with glaucoma, you may need to have your eye pressure checked every week or month until it is under control. Even when your eye pressure is at a safe level, you may need to see your doctor several times a year for checkups[17].
Treatment Options
The damage caused by glaucoma can’t be reversed. But treatment and regular checkups can help slow or prevent vision loss, especially if the disease is found in its early stages[3]. Treatment focuses on improving drainage and reducing the pressure in your eyes to stop the condition from progressing[1].
All current treatments for open-angle glaucoma are designed to lower eye pressure[9]. Treatment options include medications (usually eye drops), laser treatment, and surgery[9].
Medications (Eye Drops)
Eye drops are often the first choice for treating patients with open-angle glaucoma[5]. These medications decrease eye pressure by helping the eye’s fluid drain better or by decreasing the amount of fluid made by the eye[4]. For many people, a combination of medications and laser treatment can safely control eye pressure for years[15].
Common types of eye drops include:
Prostaglandins: These increase the outflow of fluid from the eye, helping to reduce eye pressure. Medicines in this category include latanoprost, travoprost, tafluprost, bimatoprost, and latanoprostene bunod. They are prescribed for once-a-day use. Possible side effects include mild reddening and stinging of the eyes, darkening of the iris, darkening of the pigment of the eyelashes or eyelid skin, and blurred vision[10].
Beta blockers: These reduce the production of fluid in the eye, helping to lower eye pressure[10]. Eye drops, commonly nonspecific beta-blocker or prostaglandin analog drops, generally are the first-line treatment to reduce eye pressure[6].
Medications must be taken daily to keep eye pressure at a safe level[15]. It is normal for your medication prescriptions to change over time, and changing medications does not necessarily mean that your condition is worsening[15].
Laser Treatment
Selective Laser Trabeculoplasty (SLT) is a laser procedure used for open-angle glaucoma. A recent randomized clinical trial demonstrated that laser therapy can be effective as first-line treatment[9]. It can also be effective in patients already on eye drops[15].
SLT uses low levels of laser light to improve drainage of fluid through the natural drainage pathway out of the eye[15]. The procedure targets the trabecular meshwork to enhance fluid outflow[9].
Surgery
Laser treatment and surgery usually are reserved for patients in whom medical treatment has failed[6]. When other treatments do not lower eye pressure to the desired level, your doctor may recommend some form of surgery[15].
Conventional or incisional surgery is done in a hospital or surgery center, using a microscope and microsurgery instruments, and includes making a cut (incision) in the eye[15]. These procedures lower eye pressure by creating an opening in the wall of the eye so fluid can easily escape[9]. Another surgical approach is to implant a tube called a shunt to channel fluid out of the eye[9].
There are also minimally invasive glaucoma surgeries (MIGS) available[1]. Your treatment plan will depend on the type of glaucoma you have, how far it has advanced, and your general health[9].
Living With Open-Angle Glaucoma
A diagnosis of glaucoma doesn’t have to limit your life. You can continue with what you were doing before glaucoma was diagnosed, make new plans, and start new ventures[17]. However, some daily activities such as driving or playing certain sports may become more challenging[17].
Managing Your Medications
Try to schedule time for taking medication around daily routines such as waking, mealtimes, and bedtime. In this way, your medications will become a natural part of your day[17].
Lifestyle Modifications
While lifestyle changes cannot prevent open-angle glaucoma, certain habits may help support eye health and overall well-being[20].
Physical activity: Patients with glaucoma should strive to keep their head above their heart and avoid sustained forceful exhalation against a closed airway (Valsalva maneuvers)[18]. Aerobic exercise such as walking, jogging, biking, or tennis is advisable[18]. Moderate exercise can help reduce eye pressure[16]. Cardiovascular exercises enhance general eye health and vision[16].
Patients with glaucoma should avoid exercises during which their head is below their heart, such as certain yoga poses and headstands[18]. They should also avoid lifting heavy weights or playing wind instruments[18].
Diet and nutrition: A well-rounded diet rich in dark, leafy greens and omega-3 fatty acids may have a positive effect on eye health[19]. Foods high in antioxidants, like leafy greens and colorful fruits, are particularly beneficial[16]. Flavonoids found in berries, red onions, legumes, and dark chocolate have been shown to increase blood flow to the optic nerve[18]. Consider limiting coffee to under three cups a day, as high caffeine intake may raise eye pressure[20].
Stress management: Excessive stress may worsen glaucoma by increasing eye pressure. Managing stress effectively is essential[16]. Recent studies have pointed to meditation as a helpful tool to combat high eye pressure. Research found that 75 percent of patients who practiced meditation daily had more than a 25 percent drop in eye pressure after three weeks[19]. Mindfulness is low-risk and has the potential to have many benefits[19].
Sleep: Eye pressure can increase overnight due to head and body positions during sleep. To minimize this effect, patients with rapid visual field progression can try to keep their heads elevated when sleeping by either stacking pillows or elevating the head of the bed[18].
Emotional Support
In addition to taking care of your physical health, it’s equally important to pay attention to the emotional and psychological aspects of having this disease. Be sure to share your feelings, especially in the beginning. Confide in your spouse, a relative, a close friend, or a member of the clergy. You may also want to talk with other people who have glaucoma. Sharing ideas and feelings about living with a chronic health condition can be useful and comforting[17].
Regular Monitoring
A good working relationship with your eye doctor is the key to effective glaucoma care[17]. Regular checkups are essential to monitor the disease and adjust treatment as needed. If you do not feel confident and comfortable with your doctor, remember, you always have the right to seek a second opinion[17].
