What Is Glaucoma? A Complete Patient Guide

Glaucoma is not a single disease but rather a family of conditions that share the common feature of optic nerve damage. Each type has distinct causes, risk profiles, and treatment approaches.

Open-angle glaucoma is the most common form, accounting for roughly 90 percent of all glaucoma cases. The drainage angle where the iris meets the cornea remains physically open, but the microscopic drainage channels within the trabecular meshwork become less efficient over time. Pressure rises gradually, and vision loss develops slowly over months or years without noticeable symptoms in the early stages.

In angle-closure glaucoma, the drainage angle becomes physically blocked when the iris shifts forward. This can happen slowly (chronic angle closure) or suddenly (acute angle closure). An acute angle-closure attack is a medical emergency that causes severe eye pain, headache, nausea, and sudden blurred vision. If you experience these symptoms, seek immediate care to prevent permanent vision loss. You can learn more about this urgent condition on our angle-closure glaucoma emergency page.

Secondary glaucoma develops as a result of another condition or factor, such as eye trauma, inflammation, certain medications like corticosteroids, or advanced cataracts. The elevated eye pressure in these cases stems from an identifiable cause rather than a primary drainage deficiency. Treatment involves addressing both the underlying cause and managing the increased intraocular pressure to protect the optic nerve.

Some children are born with structural abnormalities in the eye's drainage system that lead to elevated pressure from birth or early childhood. Signs may include excessive tearing, light sensitivity, and an unusually large or cloudy cornea. Early surgical intervention is typically needed to prevent permanent vision loss in these young patients.

Glaucoma typically affects peripheral vision first, creating subtle blind spots that may go unnoticed during everyday activities. As the disease progresses, these gaps widen and can eventually encroach on central vision, making tasks like reading and driving more difficult. Many patients describe the experience as looking through a narrowing tunnel. To better understand how glaucoma may affect your long-term vision, we encourage open conversations with your care team about your individual prognosis.

Genetics play a meaningful role in glaucoma risk, especially for open-angle glaucoma. If a close relative has been diagnosed, your own risk is significantly higher than someone without that family connection. We recommend sharing your family eye health history with your doctor so that screening can begin at the right time, even if you have no current symptoms.

Cataracts involve clouding of the eye's natural lens, causing blurry or hazy vision that can typically be corrected with surgery. Glaucoma damages the optic nerve and causes permanent vision loss that cannot be reversed through any procedure. It is possible to have both conditions at the same time, and in some cases treatment can be coordinated to address both during a single procedure. Visit our glaucoma overview page to learn more about how we approach both of these common conditions.

There is currently no cure for glaucoma, but the disease can be effectively managed to slow or halt further vision loss. Treatment options include prescription eye drops, laser procedures such as selective laser trabeculoplasty, and surgical interventions for more advanced cases. The goal of every treatment plan is to lower eye pressure to a level that prevents additional optic nerve damage. For a deeper look at long-term management strategies, visit our page on whether glaucoma can be cured or reversed.

Without treatment, glaucoma progresses at a variable but steady pace. Peripheral vision continues to narrow, and eventually central vision can be affected, potentially leading to significant visual impairment or blindness. Early and consistent treatment is the most effective way to preserve the vision you have. Even patients diagnosed at a moderate stage can maintain functional, meaningful vision for decades with proper care and regular monitoring.

The American Academy of Ophthalmology recommends a baseline comprehensive eye exam at age 40. Adults without additional risk factors should be screened every two to four years between ages 40 and 54, every one to three years between ages 55 and 64, and every one to two years after age 65. If you have risk factors such as a family history, African American heritage, or elevated eye pressure, more frequent exams may be appropriate. Our team can help determine the right screening schedule based on your individual profile.