Narrow angle glaucoma, also known as angle closure glaucoma, is a type of glaucoma caused by a narrowing or closure of the anterior chamber angle in the eye. The anterior chamber is the fluid-filled space between the cornea and the iris. The angle refers to the area between the iris and the cornea where aqueous humor drains from the anterior chamber.
In narrow angle glaucoma, the flow of aqueous humor becomes blocked at the anterior chamber angle, causing a rapid rise in intraocular pressure. This results in permanent damage to the optic nerve and vision loss if not treated promptly.
Some key points about narrow angle glaucoma:
- It is caused by a narrow or obstructed anterior chamber angle, often due to shallow anterior chambers or bulky lens. This prevents aqueous humor from draining properly.
- It can occur gradually or as an acute attack. The acute attack is a medical emergency and causes sudden vision loss.
- Risk factors include being hyperopic, older age, and of East Asian descent. Shallow anterior chamber and narrow angles are more common in these groups.
- Pupil dilation can trigger or worsen an acute angle closure attack by further narrowing the angle. Drugs like benperidol that cause pupillary dilation are therefore contraindicated in narrow angle glaucoma.
- Treatment often starts with laser iridotomy to create an opening in the iris and relieve pressure. Laser iridoplasty or lens extraction may also be done. Acute attacks also require immediate medical therapy to lower pressure.
- Features include narrow or occludable anterior chamber angles, high intraocular pressure, redness, vision loss, headache, nausea, and eye pain during acute attacks.
- Diagnosis is by slit lamp examination to view the anterior chamber angle, gonioscopy, visual field testing, tonometry to measure eye pressure, and ophthalmoscopy to assess optic nerve damage.
- Prognosis depends on the timeliness of treatment and the amount of permanent vision loss before treatment. Early diagnosis and treatment provide the best outcomes.
In summary, narrow angle glaucoma is a type of glaucoma caused by a narrowed or closed anterior chamber angle in the eye, preventing drainage of aqueous humor. Prompt treatment is needed to prevent optic nerve damage and permanent vision loss. Drugs that cause pupillary dilatation, like benperidol, must be avoided. Alternative agents should be used instead in patients with narrow angle glaucoma.« Back to Glossary Index