Comparing the Different Types of Glaucoma
Primary Open-Angle Glaucoma
Primary open-angle glaucoma is the most common form of the disease, accounting for the vast majority of glaucoma cases. Because it rarely causes noticeable symptoms in its early stages, it is often called the silent thief of sight, and regular eye exams are the most reliable way to catch it before serious damage occurs.
This type develops when fluid inside the eye, called aqueous humor, drains too slowly through the eye's natural drainage system. Even though the drainage angle looks open and unobstructed, microscopic blockages prevent fluid from flowing out properly. Pressure gradually builds inside the eye, slowly damaging the optic nerve over months or years.
Certain factors make a person significantly more likely to develop primary open-angle glaucoma.
- Adults over 40, with risk increasing with each decade
- Family history of glaucoma in a parent or sibling
- African American, Hispanic, or Asian ancestry
- Elevated eye pressure, also called ocular hypertension
- Thin corneas or a large cup-to-disc ratio in the optic nerve
- Diabetes, high blood pressure, or cardiovascular disease
- Severe nearsightedness, also called myopia
Most people have no symptoms at all in the early stages of this condition. As it progresses, side vision begins to narrow, and you may notice difficulty seeing in low light or trouble judging distances. By the time these changes become obvious, meaningful vision loss may have already taken place, which is why proactive screening matters so much.
Our team uses a thorough set of diagnostic tests to detect and track this condition over time.
- Tonometry to measure the pressure inside your eye
- Gonioscopy to closely examine the eye's drainage angle
- Automated visual field testing to map peripheral vision
- Color stereoscopic optic-nerve photography to document the nerve's appearance
- Optical coherence tomography (OCT) to measure the thickness of nerve fiber layers
Treatment focuses on lowering eye pressure to protect the optic nerve from further damage. The approach is always tailored to the individual patient by their eye doctor.
- Prescription eye drops, such as prostaglandin analogs, beta-blockers, or alpha agonists, to reduce fluid production or improve drainage
- Selective Laser Trabeculoplasty (SLT), a laser procedure that improves fluid outflow through the drainage system
- Minimally Invasive Glaucoma Surgery (MIGS), including micro-stent implants, for mild to moderate cases
- Trabeculectomy or tube shunt surgery for more advanced disease
Most people with well-controlled primary open-angle glaucoma continue to live full, active lives. Staying consistent with eye drops, attending all follow-up appointments, and reporting any changes in your vision are the pillars of successful long-term management.
Angle-Closure Glaucoma
Angle-closure glaucoma occurs when the iris, the colored part of the eye, shifts forward and physically blocks the eye's drainage angle. This blockage can happen gradually over time or suddenly, and the sudden form is a true medical emergency.
In angle-closure glaucoma, the drainage angle between the iris and the cornea becomes narrowed or completely blocked. When fluid cannot exit the eye, pressure rises sharply. Acute attacks can cause irreversible vision damage within hours if not treated immediately. The chronic form builds slowly, often without dramatic warning signs.
Certain anatomical features and personal characteristics raise the risk of angle-closure glaucoma.
- Adults of Asian, Inuit, or Hispanic descent
- Women, who are affected more often than men
- Adults over 55
- Farsighted individuals, whose eyes tend to be smaller and more crowded
- People with a family history of angle-closure glaucoma
- Those with cataracts causing lens swelling
- People taking certain medications that dilate the pupil, such as some antidepressants or decongestants
An acute angle-closure attack is a medical emergency. If you experience any of the following, seek care immediately rather than waiting for a scheduled appointment.
- Sudden, intense eye pain
- Severe headache
- Rapid blurring or loss of vision
- Halos or rainbow rings around lights
- Red, watery eyes
- Nausea or vomiting
Acute attacks are treated urgently with medications to lower eye pressure quickly, followed by laser iridotomy, a procedure that creates a small opening in the iris to restore normal fluid flow. The unaffected eye is typically treated as well, since it is at risk for a future attack. In some situations, surgery such as trabeculectomy or lens extraction is needed when laser treatment alone is not sufficient.
If you have a narrow drainage angle but have not had an attack, your eye doctor may recommend preventive laser iridotomy before an emergency can occur. Routine monitoring allows our team to detect gradual angle narrowing and intervene early, which is far preferable to treating an acute crisis.
Normal-Tension Glaucoma
Normal-tension glaucoma is a form of open-angle glaucoma in which the optic nerve sustains damage even though eye pressure stays within the range considered statistically normal. This type can be more difficult to identify and requires a comprehensive evaluation beyond simple pressure measurements.
In most forms of glaucoma, elevated eye pressure is the primary driver of nerve damage. In normal-tension glaucoma, pressure readings fall below 21 mmHg, the conventional upper boundary of normal, yet the optic nerve still deteriorates. Researchers believe that factors such as reduced blood flow to the optic nerve or increased nerve sensitivity may play an important role.
Some populations and health conditions appear to be associated with a higher likelihood of developing this condition.
- Individuals of Japanese ancestry, where this type is especially prevalent
- Women, particularly after menopause
- Those with a family history of normal-tension or low-pressure glaucoma
- People with low blood pressure, especially during nighttime hours
- Those with vasospastic conditions such as migraines or Raynaud's phenomenon
- People with sleep apnea or other conditions affecting blood oxygen levels
Because eye pressure appears normal, this type can be overlooked if only a pressure check is performed. A complete evaluation of the optic nerve using OCT imaging, optic-nerve photography, and automated visual field testing is essential to diagnose and track this condition accurately. Our team uses this full range of diagnostics during every glaucoma assessment.
Treatment aims to lower eye pressure further below its baseline level, even when it is already in the normal range, and to support healthy blood flow to the optic nerve. This may include prescription eye drops, management of related conditions like sleep apnea or low blood pressure, and in some cases, lifestyle adjustments such as regular moderate exercise. Your eye doctor will determine the most appropriate plan based on your overall health picture.
Secondary Glaucoma
Secondary glaucoma develops when an identifiable underlying cause disrupts the eye's normal fluid drainage. Unlike primary forms, this type is directly linked to another eye condition, systemic disease, injury, or medication. Treating the root cause is an important part of managing secondary glaucoma alongside controlling eye pressure.
Any condition that interferes with the eye's drainage system can trigger secondary glaucoma. Our team at Rhode Island Eye Institute has expertise in two particularly common forms, pseudoexfoliative glaucoma, caused by a buildup of protein-like material that clogs the drainage system, and pigmentary glaucoma, in which pigment granules shed from the iris block fluid outflow. Both can cause significant pressure elevation and require targeted management.
A range of conditions and circumstances can cause or contribute to secondary glaucoma.
- Uveitis or other eye inflammation that damages drainage structures
- Prolonged use of corticosteroid (steroid) medications
- Abnormal blood vessel growth in the eye, often associated with diabetes
- Eye trauma or injury that damages drainage tissues
- Advanced cataracts that cause lens swelling or protein leakage
Symptoms vary depending on the underlying cause. Some patients experience gradual, painless vision loss similar to primary open-angle glaucoma, while others develop sudden eye pain, redness, light sensitivity, or halos around lights. A thorough eye exam, including gonioscopy and imaging, helps our team identify the source and guide treatment decisions.
Controlling secondary glaucoma typically requires addressing both the underlying cause and the elevated eye pressure. This may involve treating active inflammation, adjusting or stopping steroid medications when possible, managing systemic conditions like diabetes, and using glaucoma eye drops, laser treatment, or surgery as needed to reduce pressure and protect the optic nerve.
Congenital Glaucoma
Congenital glaucoma is a rare condition present at or shortly after birth, caused by an abnormality in the eye's drainage system that develops before birth. Prompt diagnosis and treatment are critical to protecting a child's developing vision and preventing lasting impairment.
In congenital glaucoma, the drainage structures inside the eye fail to form correctly during fetal development. Fluid accumulates and pressure rises within the eye, which can enlarge the eye abnormally and damage the optic nerve at a stage when vision development is still critical.
Parents and caregivers are often the first to notice that something seems different about a baby's eyes. Common signs that warrant prompt evaluation include the following.
- Eyes that appear unusually large, or that differ noticeably in size
- Cloudy or hazy-looking corneas
- Excessive tearing unrelated to crying
- Sensitivity to light, causing squinting or turning away from light sources
- Frequent eye rubbing or keeping the eyes shut in bright environments
Surgery is the primary treatment for congenital glaucoma, since medications are generally less effective in very young children. Procedures such as goniotomy or trabeculotomy are used to open or reconstruct the blocked drainage pathways. Most children benefit from early intervention and go on to develop functional vision, though they will require ongoing monitoring throughout childhood and into adulthood.
Frequently Asked Questions
These answers address common questions about glaucoma that go beyond the basics covered above.
At this time, there is no cure for glaucoma, and any vision already lost to the disease cannot be restored. However, with consistent treatment, regular monitoring, and timely intervention, most people are able to maintain useful, functional vision for the rest of their lives. The goal of all glaucoma care is to prevent further damage, not to reverse what has already occurred.
Missing an occasional dose is unlikely to cause immediate harm, but consistency is genuinely important with glaucoma medications because they work by maintaining steady, lower pressure around the clock. If you miss a dose, take it as soon as you remember, but do not double up. If remembering to use drops is a recurring challenge, talk with your eye doctor about reminder strategies, medication combinations, or longer-acting treatment options that may be available to you.
You cannot tell on your own whether your glaucoma is being controlled, because the disease is usually painless and vision changes are too gradual to notice day to day. Your eye doctor tracks success through regular pressure measurements, optic nerve imaging, and visual field testing. Stable results over time are the clearest sign that your treatment plan is doing its job, which is why attending every follow-up visit matters even when you feel completely fine.
Lifestyle changes cannot replace medical treatment, but some habits may support eye health alongside your prescribed care. Regular moderate aerobic exercise has been shown to modestly reduce eye pressure in some patients. Avoiding positions that place your head below your heart for extended periods, such as certain yoga inversions, may also be advisable depending on your type of glaucoma. Always discuss activity modifications with your eye doctor before making changes, as guidance can vary based on your specific situation.
Sudden and severe eye pain, rapid vision loss, seeing halos or colored rings around lights, nausea, and headache together are warning signs of an acute angle-closure attack, which is a true ocular emergency. Do not wait for a scheduled appointment if you experience these symptoms. Seek immediate care at an emergency room or urgent eye care provider, as permanent damage can occur within hours without treatment.
Yes. Juvenile open-angle glaucoma can develop in children and teenagers who were born without any drainage abnormality. Children can also develop secondary glaucoma following an eye injury, as a result of certain medications, or in association with other health conditions. Any persistent eye redness, tearing, light sensitivity, or vision concern in a child should be evaluated by an eye doctor promptly rather than being observed at home.
Expert Glaucoma Care at Rhode Island Eye Institute
Rhode Island Eye Institute brings together fellowship-trained glaucoma specialists, advanced diagnostic technology, and a full range of medical and surgical treatment options under one roof. Our team is committed to giving every patient a thorough, individualized evaluation and a clear path forward for protecting their vision. We welcome you to schedule a comprehensive eye exam and experience the depth of subspecialty care our practice provides.