Glaucoma is when the optic nerve in the eye becomes damaged. In narrow angle glaucoma, this occurs because the angle between the iris and cornea is too narrow, preventing fluid from draining from the eye.
When fluid cannot drain from the eye as it should, pressure increases inside the eyeball, which can potentially lead to permanent damage if a person does not get treatment.
Narrow angle glaucoma can be acute or chronic. The acute form requires immediate medical attention. For both types, early diagnosis and treatment can help prevent vision loss.
In this article, learn more about narrow angle glaucoma, including its causes, symptoms, diagnosis, and treatment options.
Narrow angle glaucoma is a condition that causes an increase in pressure inside the eye, potentially damaging the optic nerve. This occurs due to changes in the iris, or the colored part of the eye, and the cornea, which is the transparent tissue that sits over the top of it.
The eye constantly produces fluid, which gives the eyeball its shape. Channels around the iris allow the fluid to drain away. If the iris presses forwards, the angle between the iris and cornea narrows.
There are two forms of narrow angle glaucoma: acute and chronic. In the chronic form, the angle remains narrow but not completely blocked. Some fluid can still drain, but not as much.
In the acute form, the iris obstructs the drainage channels, causing a sudden increase in pressure inside the eye. A truly acute narrow-angle closure will not resolve on its own.
However, people can have intermittent angle closures that do resolve on their own, such as while a person is sleeping.
The rates of narrow angle glaucoma vary between ethnicities. Among white people, it is rare, with an estimated prevalence of 3.8% among white people in the United States. It is much more common in people with East Asian heritage, particularly people from Thailand, Myanmar, and China.
Around 9 in 10 glaucoma cases in white people are open angle. In Asian populations, around 9 in 10 of all glaucoma cases are narrow angle.
Narrow angle glaucoma can have a serious impact on vision. Despite being less common than open angle glaucoma, narrow angle is the cause of
If a person does not get treatment, both acute and chronic narrow angle glaucoma can lead to permanent vision loss. The acute form develops quickly, so it can cause vision changes within hours.
The symptoms of narrow angle glaucoma vary depending on whether it is chronic or acute. The acute form causes a sudden onset of symptoms,
- severe one-sided eye pain
- nausea and vomiting
- blurred vision
- rainbow-colored halos around lights
Signs of acute angle-closure glaucoma that a doctor may observe during an eye exam include:
- dilated and fixed pupil
- dilated blood vessels
- cloudy cornea
- increased eye pressure
- swollen optic nerve
The symptoms of chronic narrow angle glaucoma can be less noticeable and
- increase eye pressure
- adhesions on the iris
- damage to the optic nerve
- visual field loss, although there may be no effect on the clarity of a person’s vision
Doctors describe how severe a person’s angle closure is by using a staging system. These stages include:
- Primary angle closure suspect (PACS): This is when the iris is touching the spongy tissue near the cornea, which is known as the trabecular meshwork. Eye pressure is typical, and there are no adhesions between the iris and angle structures and no damage to the optic nerve.
- Primary angle closure (PAC): This means that pressure is elevated, but there is no damage to the optic nerve.
- Primary angle closure glaucoma (PACG): This describes optic nerve damage and raised eye pressure. However, in chronic forms, the pressure can be normal.
Narrow angle glaucoma occurs when fluid cannot drain from the eye as it should.
- Family history: People inherit the features of their eyes from their parents and, therefore, risk of narrow angle glaucoma.
- Older age: Narrow angles are not present in younger people, but because the lens in the eye continues to grow with age, it can push the iris forward over time. This narrows the angle between the iris and cornea.
- Sex: Females develop narrow angle glaucoma more often than males, with an incidence ratio of 4:1. It is unclear why this is the case.
Treatment for narrow angle glaucoma involves reducing pressure in the eye and taking steps to improve fluid drainage.
In acute cases, this involves emergency treatment to stabilize eye pressure via medications, which
- carbonic anhydrase inhibitors
- prostaglandin analogs
When the pressure improves, doctors will perform a procedure to create a drainage channel in the iris. This is known as a peripheral iridotomy. Usually, this procedure is successful and produces long-lasting results.
For chronic narrow angle glaucoma, doctors
Yes, narrow angle glaucoma is curable. The outcome depends on how quickly doctors detect and treat it. Seeking treatment early is crucial for the long-term outcome of the condition.
In people who have not undergone surgery for narrow angle glaucoma, there is a risk that certain activities or medications will cause an acute attack.
For this reason, people with a history of narrow glaucoma should try to avoid dim light, as this can cause the irises to dilate wide open. Eye drops that dilate the eyes can also pose a risk, along with many other medications, including:
- antihistamines such as diphenhydramine (Benadryl), loratadine (Claritin), and cetirizine (Zyrtec)
- certain antidepressants, such as fluoxetine (Prozac), paroxetine (Paxil), amitriptyline (Elavil), and duloxetine (Cymbalta)
- the headache medication sumatriptan (Imitrex)
- sulfa drugs such as topiramate (Topamax), acetazolamide (Diamox), and trimethoprim-sulfamethoxazole (Bactrim)
- Botox injections near the eyes
This is not a comprehensive list. Anyone who has narrow angle glaucoma and has not had an iridotomy needs to check with a doctor before taking any drug or supplement.
There is some concern that exercise may increase eye pressure in people with glaucoma. However, a
Narrow angle glaucoma occurs when fluid cannot drain from the eye due to narrowing between the iris and cornea. This leads to a buildup of fluid and increased pressure in the eye. When this damages the optic nerve, it can affect vision.
This type of glaucoma is relatively rare overall, but it is much more common among people with East Asian and Inuit heritage. The condition can be chronic or acute, with the acute form being a medical emergency.
Treatment involves reducing pressure in the eye via medications, and may also involve procedures to create new drainage channels in the iris.