Key points
- A narrow angle means the iris sits close to the eye's drain.
- Laser iridotomy helps, but the benefit is modest if the angle is only narrow.
- Lens surgery can work better when pressure is high.
- Sudden pain, redness, halos and nausea need emergency care now.
What a narrow angle is
Fluid leaves the eye through a drain in the angle where the iris meets the cornea. In some eyes, often farsighted ones, the iris sits close to that drain. Doctors call this a narrow angle, or a primary angle-closure suspect.[1]
Angle-closure disease ranges from a narrow angle with a healthy eye, to angle closure with raised pressure or scarring, to angle-closure glaucoma with nerve damage.[2]
How it's diagnosed
The key test is gonioscopy in a dim room, using a contact lens with mirrors to see the drain. Anterior segment OCT or ultrasound can add detail.[2]
When a laser helps
Laser peripheral iridotomy makes a tiny opening in the iris so the angle can open. In the ZAP trial of 889 people with narrow angles in both eyes, the laser roughly halved the rate of angle-closure events, but those events were uncommon in both treated and untreated eyes. The researchers advised against routine laser for everyone with narrow angles.[3]
Current guidance calls for a shared decision based on your own risk.[2] Laser is more clearly worthwhile if you've had an attack in the other eye. About half of those fellow eyes can have an attack within five years without treatment.[2]
When lens surgery is better
For people with angle closure and raised pressure, or angle-closure glaucoma, removing the eye's natural lens can open the angle more fully. In the EAGLE trial, early lens extraction gave better pressure control and quality of life than laser iridotomy plus drops, and was cost-effective.[4]
The emergency to know
If the angle closes suddenly, pressure can rise very fast. Signs are sudden eye pain and redness, blurred vision, halos around lights, headache, and nausea or vomiting.[5] This is an emergency. Go to an emergency department now. Treatment lowers the pressure with medicines, then opens the angle with laser.[2]
When to see a doctor
Go to an emergency department now for sudden eye pain and redness with blurred vision, halos, headache, nausea or vomiting.
Emergency: If you have sudden eye pain with redness, blurred vision, halos around lights, headache, nausea or vomiting, or sudden vision loss or a curtain over your vision, go to an emergency department now or call 911.
Sources and references
- Wright C, Tawfik MA, Waisbourd M, Katz LJ. Primary angle-closure glaucoma: an update. Acta Ophthalmol. 2016;94(3):217-225. View source (opens in a new tab)
- Gedde SJ, Chopra V, Vinod K, et al; American Academy of Ophthalmology Preferred Practice Pattern Glaucoma Committee. Primary Angle-Closure Disease Preferred Practice Pattern. Ophthalmology. 2026;133(4):P153-P201. doi:10.1016/j.ophtha.2025.12.030 View source (opens in a new tab)
- He M, Jiang Y, Huang S, et al. Laser peripheral iridotomy for the prevention of angle closure: a single-centre, randomised controlled trial. Lancet. 2019;393(10181):1609-1618. View source (opens in a new tab)
- Azuara-Blanco A, Burr J, Ramsay C, et al. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet. 2016;388(10052):1389-1397. View source (opens in a new tab)
- National Eye Institute. Glaucoma. National Institutes of Health. View source (opens in a new tab)
This article is general education for adults and is not a substitute for personal medical advice.