Chronic Glaucoma (Primary Open-Angle Glaucoma)

What happens in open-angle glaucoma

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, located in the "angle" where the iris meets the cornea. In open-angle glaucoma, the angle is open, but the drain works less efficiently, so pressure inside the eye (intraocular pressure, IOP) slowly rises.

Raised pressure, combined with how vulnerable an individual's optic nerve is, damages the nerve fibers that carry visual signals to the brain. Damage starts in the mid-peripheral vision and spreads slowly. The brain fills in gaps, so people rarely notice until a large part of the field is gone.

Normal IOP is about 10 to 21 mmHg. Some people develop glaucoma with normal pressure (normal-tension glaucoma), and some have high pressure without damage (ocular hypertension), which is monitored and sometimes treated.

Chronic vs acute glaucoma

See acute glaucoma for the emergency form, and glaucoma for an overview of all types.

Symptoms

• Early: none. Vision is clear, the eye is not painful or red.
• Moderate: patchy blind spots in side vision, usually not noticed.
• Advanced: tunnel vision, bumping into objects, trouble with steps, curbs and driving.
• End stage: loss of central vision and blindness.

Risk factors

• age: risk rises steadily after 40 and especially after 60
• ethnicity: Black adults have several times higher risk and earlier onset; Hispanic and Latino adults also have higher risk with age
• family history: a parent or sibling with glaucoma
• raised eye pressure
• thin central cornea
• high myopia (nearsightedness)
• diabetes, high blood pressure and very low blood pressure at night
• long-term corticosteroid use, especially steroid eye drops
• previous eye injury

Diagnosis

Glaucoma is found through a comprehensive eye exam by an optometrist or ophthalmologist, including:

• tonometry: measures eye pressure
• ophthalmoscopy: examines the optic nerve for "cupping" (enlargement of the central cup)
• visual field testing: maps side vision to detect blind spots
• optical coherence tomography (OCT): measures the thickness of the nerve fiber layer
• gonioscopy: checks that the drainage angle is open
• pachymetry: measures corneal thickness

The American Academy of Ophthalmology advises a baseline exam at 40 and regular exams after, more often with risk factors.

Treatment

The aim is to lower eye pressure enough to stop further damage. A target pressure is set for each person.

Eye drops

Usually the first treatment. Used every day for life:

• prostaglandin analogs (latanoprost, bimatoprost, travoprost): once daily, often first choice. They can darken the iris and lengthen lashes.
• beta blockers (timolol): can affect the heart and lungs; avoid with asthma.
• alpha agonists (brimonidine)
• carbonic anhydrase inhibitors (dorzolamide, brinzolamide)
• Rho kinase inhibitors (netarsudil)

Tips: close the eye and press gently on the inner corner for 1 to 2 minutes after each drop to reduce absorption into the body, and wait 5 minutes between different drops.

Laser

Selective laser trabeculoplasty (SLT) improves drainage through the trabecular meshwork. It is a quick outpatient procedure and is now an accepted first-line treatment, reducing or avoiding the need for drops in many people. The effect can wear off over years and may be repeated.

Surgery

For glaucoma that progresses despite drops and laser:

• minimally invasive glaucoma surgery (MIGS): tiny stents or devices, often combined with cataract surgery
• trabeculectomy: creates a new drainage channel
• tube shunts: drainage devices

Living with glaucoma

• Use drops exactly as prescribed; skipping doses is the most common reason for progression.
• Keep all follow-up appointments, typically every 3 to 12 months.
• Tell all your doctors you have glaucoma; some medicines, especially steroids and some anticholinergics, can affect eye pressure.
• Regular exercise is safe and may modestly lower eye pressure. Avoid prolonged head-down positions.
• Check whether you meet vision standards for driving.

Frequently asked questions

What is chronic glaucoma?

Chronic glaucoma, usually primary open-angle glaucoma, is a slowly progressive condition in which the optic nerve is damaged, typically due to raised eye pressure from inefficient fluid drainage. It causes gradual, painless loss of side vision.

What are the first signs of open-angle glaucoma?

There usually are none. Early open-angle glaucoma has no pain and no noticeable vision change. It is detected through eye exams that measure pressure, look at the optic nerve and test side vision. That is why regular exams matter.

Can glaucoma be cured?

No, but it can be controlled. Eye drops, laser and surgery lower eye pressure and usually stop or slow further damage. Vision already lost cannot be restored, so early detection and consistent treatment are key.

Will I go blind from glaucoma?

Most people with treated glaucoma keep useful vision for life. Blindness is much more likely when glaucoma is diagnosed late or treatment is not followed. Using drops consistently and attending checkups greatly reduce the risk.