Glaucoma

How glaucoma damages vision

The front of the eye is filled with a clear fluid (aqueous humor) that is constantly made and drained through a mesh-like channel called the trabecular meshwork, where the iris meets the cornea (the drainage angle). If drainage is too slow, pressure inside the eye (intraocular pressure) rises. Over time, raised pressure and other factors such as poor blood flow damage the nerve fibers of the optic nerve. As fibers are lost, blind spots develop, usually starting in the side (peripheral) vision.

Normal eye pressure is roughly 10 to 21 mmHg. Some people develop glaucoma at normal pressure (normal-tension glaucoma), and others have high pressure without nerve damage (ocular hypertension).

Types of glaucoma

Primary open-angle glaucoma

The most common type in the US. The drainage angle looks open, but drainage is slow. Pressure rises gradually, and vision loss is painless and slow over years. Both eyes are usually affected, often unevenly.

Angle-closure glaucoma

The iris bulges forward and blocks the drainage angle.

• Acute angle-closure: pressure rises suddenly, causing severe eye pain, a red eye, blurred vision, halos around lights, headache, nausea and vomiting. It can cause blindness within hours to days and needs emergency treatment. See acute glaucoma.
• Chronic angle-closure: the angle closes gradually, causing silent damage like open-angle glaucoma.

It is more common in people of East Asian descent, women, older adults and people who are farsighted.

Normal-tension glaucoma

Optic nerve damage occurs with eye pressure in the normal range. Poor blood flow to the nerve may play a role. It is more common in people of Japanese descent and in women.

Secondary glaucoma

Caused by another condition: eye injury, inflammation (uveitis), steroid use, advanced cataract, diabetes-related blood vessel growth (neovascular glaucoma), or pigment or flaky material that clogs the drain (pigmentary and pseudoexfoliation glaucoma).

Childhood glaucoma

Rare. Babies may have large, cloudy eyes, watering and light sensitivity, and need urgent assessment.

Symptoms

Open-angle glaucoma

• no symptoms in the early stages
• gradual loss of peripheral vision, often unnoticed because the other eye compensates
• in advanced stages, tunnel vision and eventually loss of central vision

Acute angle-closure glaucoma

• sudden, severe eye pain
• a red eye
• blurred vision and rainbow-colored halos around lights
• headache, nausea and vomiting
• a mid-sized pupil that does not react well to light

Risk factors

• age over 60 (over 40 in Black adults)
• Black, Hispanic or Latino ancestry, for open-angle glaucoma
• East Asian ancestry, for angle-closure glaucoma
• family history of glaucoma
• high eye pressure
• thin central cornea
• diabetes and high blood pressure
• high nearsightedness (myopia) for open-angle, farsightedness for angle-closure
• long-term steroid use
• previous eye injury or surgery

Diagnosis

A comprehensive dilated eye exam includes:

• Tonometry: measures eye pressure.
• Ophthalmoscopy: examines the optic nerve for "cupping".
• Optical coherence tomography (OCT): a scan that measures the thickness of the nerve fiber layer.
• Visual field test (perimetry): maps your side vision to find blind spots.
• Gonioscopy: a special lens to see whether the drainage angle is open or closed.
• Pachymetry: measures corneal thickness.

Treatment

Treatment aims to lower eye pressure to a target level that prevents further damage.

Eye drops

• Prostaglandin analogs (latanoprost, bimatoprost, travoprost): usually first-line, once a day at night.
• Beta-blockers (timolol): lower fluid production. Can affect asthma and heart rate.
• Alpha agonists (brimonidine) and carbonic anhydrase inhibitors (dorzolamide, brinzolamide).
• Rho kinase inhibitors (netarsudil).

Use drops exactly as prescribed, every day. Closing your eyes and pressing gently on the inner corner for 1 to 2 minutes after each drop increases absorption and reduces side effects.

Laser treatment

• Selective laser trabeculoplasty (SLT): improves drainage in open-angle glaucoma. Often used as a first treatment instead of or alongside drops.
• Laser peripheral iridotomy: makes a tiny hole in the iris to open the angle in angle-closure glaucoma, and to prevent attacks in eyes with narrow angles.

Surgery

• Trabeculectomy: creates a new drainage channel.
• Tube shunts: a small implant drains fluid.
• Minimally invasive glaucoma surgery (MIGS): tiny devices, often placed during cataract surgery.
• Cataract surgery itself can help in angle-closure glaucoma.

Emergency treatment for acute angle-closure

Medicines by drops, mouth and IV rapidly lower pressure, followed by laser iridotomy, usually in both eyes.

Living with glaucoma

• Use drops every day, even when your vision seems fine.
• Keep every follow-up appointment.
• Tell all your doctors you have glaucoma, as some medicines, including some antihistamines and decongestants, can trigger angle closure in people with narrow angles.
• Regular exercise may help lower eye pressure. Avoid head-down yoga positions if advised.
• Low-vision services help people with advanced vision loss.

Frequently asked questions

What are the early signs of glaucoma?

The most common type, open-angle glaucoma, usually has no early signs. Side vision is lost so slowly that most people do not notice until damage is advanced. That is why regular dilated eye exams are essential, especially after 40 or with risk factors.

Can glaucoma be cured?

No, and vision lost to glaucoma cannot be restored. But treatment with eye drops, laser or surgery can stop or greatly slow further damage. Most people who are diagnosed early and stick with treatment keep useful vision for life.

Is glaucoma hereditary?

Family history is a strong risk factor. Having a parent or sibling with glaucoma increases your risk several times. If glaucoma runs in your family, start regular eye exams earlier and tell your eye doctor.

What does acute glaucoma feel like?

Acute angle-closure glaucoma causes sudden, severe eye pain, a red eye, blurred vision, rainbow halos around lights, headache, nausea and vomiting. It is a medical emergency that can cause permanent blindness within hours to days if not treated.

How often should I have my eyes checked for glaucoma?

The American Academy of Ophthalmology suggests a baseline exam at 40, then every 2 to 4 years until 54, every 1 to 3 years from 55 to 64, and every 1 to 2 years from 65. People with risk factors need more frequent checks.