Narrow Angle Glaucoma

Acute Narrow Angle Glaucoma


About the Author

Melissa Flagg is an ophthalmic technician who has been examining patients on a daily basis for over 20 years.

She has had rigorous training under the supervision of an ophthalmologist and specialized in the cornea, cataracts, and retina as well as how systemic disease affects the eye. She is certified by JCAHPO as an OSC (ophthalmic scribe certified).

Glaucoma is a complicated disease that can lead to permanent loss of the peripheral vision and can eventually lead to permanent blindness. There are several different types of glaucoma:

  • Primary open angle
  • Low-tension
  • Narrow angle
  • Neovascular
  • Pigmentary
  • Inflammatory

Glaucoma is a disease that affects the way the aqueous fluid drains in the eye. Aqueous is a gel-like, clear fluid found in the anterior chamber, which is located between the iris and the cornea.

Aqueous is constantly replenished by the ciliary body located behind the iris next to the lens. The fluid flows from behind the iris through the pupil and then drains through the trabecular meshwork, a spongy tissue that allows the fluid to flow through a system of drainage tubes known as Schlemm’s canal and then out of the eye.

Sometimes the ciliary body produces too much fluid, or the fluid doesn’t drain properly, and this causes the pressure in the eye to rise. When the pressure in the eye rises, the optic nerve becomes damaged.

The optic nerve is a bundle of retinal fibers that exit the eye and travel to the occipital lobe of the brain. Each area of the retina corresponds to a specific section of the optic nerve. Essentially, the retina is one big neuron with a very long axon or tail.

When the pressure in the eye rises, it forces the optic nerve to “cup.” This creates a bowl-like appearance to the optic nerve which results in the loss of peripheral vision because it damages the fibers that create the nerve.

If we think of the optic nerve as a doughnut, the center hole would be the cupping created by the increased pressure and the doughnut would be the rim of the optic nerve. The size of the doughnut hole grows as the pressure in the eye rises, which leads to permanent vision loss (see photo below).

Optic Nerve Cupping


What is Narrow Angle Glaucoma?

Unlike primary open angle glaucoma, narrow angle glaucoma is actually quite rare. But it is much more aggressive. It is the result of a structure in the eye called the angle being too narrow, as its name suggests. The angle is where the trabecular meshwork is found and is the space between the back of the cornea and the front of the iris (see drawing below).

The Structures of the Angle


Important Definitions

Trabecular Meshwork - an area of tissue near the iris that allows the drainage of aqueous humor from the eye through the sclera (white part of the eye).

Aqueous Humor - One of two fluids in the eye that give the eye its shape and stability and provides nutrients to various avascular structures (parts of the eye without blood flow like the cornea).

Ciliary Process - Structure of the eye that produces aqueous humor and provide attachment for the suspensory ligaments that attach to and focus the lens.

In most people, this angle is wide open as in the drawing below. Those of us in ophthalmology describe it as “wide enough to do the backstroke in.” In some patients, however, this structure is very narrow.

Patients who are hyperopic (farsighted) have very short eyes, and this naturally puts them at risk for narrow angles because the structures of the eye are essentially compressed together. Myopic (nearsighted) patients have long eyes, causing the anatomical structures to be spread out.

When the iris dilates, it folds like an accordion. In a patient with open angles there is plenty of room to accommodate the bunched up tissue of the iris, but in a patient with narrow angles, the iris can get stuck in the angle and block the aqueous from draining through the trabecular meshwork. This meshwork is essentially a series of drains that allow the aqueous that is constantly produced to flow out of the eye.

When the iris gets "stuck" in the angle, it causes an extremely rapid rise in pressure. Intraocular pressure readings can reach upwards of 70mmhg. In contrast, normal pressure is between 10 and 20mmhg. The highest I’ve seen in 20 years was over 85mmhg, and the tonometer stops at 88mmhg.

The iris can also be bowed forward either by a cataract, or a buildup of aqueous. When this occurs, the iris occludes, or blocks, the angle and the result is a narrow angle glaucoma attack. In this instance, the occlusion may be progressive and happen slowly, rather than striking suddenly. But once the iris fully blocks the angle, symptoms will occur as in a narrow angle attack and may be more severe since the pressure will already be higher when the attack starts.

Symptoms of Narrow Angle Glaucoma

Because of the rapid rise in pressure, acute angle closure is extremely painful. “My eye is going to explode” is generally how most patients describe the sensation. The rapid rise in pressure also causes swelling in the cornea, which causes several distinct symptoms including:

  • Rainbows around lights
  • Nausea and/or vomiting
  • Excruciating pain (which can be a sharp pain, or a feeling of extreme pressure that many patients say feels like their eye is going to explode)
  • Extremely red sclera (the white part of the eye becomes very bloodshot)
  • Blurred, foggy or hazy vision (caused by the swelling of the cornea)
  • Pupil dilation (which is typically the cause of the narrow angle attack)

If not treated promptly, permanent vision loss typically occurs within 24 to 48 hours. It's important to seek treatment from an ophthalmologist, NOT AN EMERGENCY ROOM, as soon as these symptoms occur.

Doctors in an emergency room are not equipped to handle a narrow angle glaucoma attack, and waiting in an ER waiting area for diagnosis is a waste of precious time and cause permanent vision loss.

The ER doctors will eventually send you to an ophthalmologist, but it may be too late by then to save the vision. Always see an ophthalmologist for ANY eye problem. It is best to avoid ERs completely if at all possible when it comes to the eye.

Narrow Angle Glaucoma in One Eye

Notice the slight dilation of the patient's right eye which is characteristic of angle closure.
Notice the slight dilation of the patient's right eye which is characteristic of angle closure. | Source

Most narrow angle attacks occur after a patient enters a dark room such as a movie theater and the eye fully dilates, which is usually in about 30 minutes. It can also occur when the eye is dilated artificially with drops such as Mydriacyl® or Cyclogyl®, which is why your technician should perform a slit lamp examination prior to instilling any dilating drops.

YAG Peripheral Iridotomy


Used to constrict the pupil prior to a YAG PI.
Used to constrict the pupil prior to a YAG PI. | Source

Treatments for Narrow Angle Glaucoma

Unlike primary open angle, narrow angle glaucoma has only two treatments:

  • Peripheral Iridotomy
  • Peripheral Iridectomy

The most common of these is an Nd: YAG Peripheral Iridotomy, or YAG PI (it is sometimes also called an LPI or laser peripheral iridotomy).

This procedure involves using an Nd: YAG laser (neodymium – doped yttrium, aluminum and garnet laser) to punch a small hole through the periphery of the iris.

This allows the aqueous to reach the trabecular meshwork. An argon laser can also be used for this purpose; however, the YAG laser is much more common.

The YAG PI is performed in the office after the patient has been given a drop of Pilocarpine. This drop is used to constrict the iris (make the pupil smaller) so that the doctor can find the thinnest part of the peripheral iris to laser.

Because the drop forces the pupil to constrict by stimulating the iris sphincter muscle, it can cause the ciliary muscles to spasm which can cause a headache. This is a very common side effect of the drop and can be alleviated with typical headache remedies such as ibuprofen or acetaminophen.

The procedure only takes about 10 minutes and can be painful. I have seen a number of patients flinch during the procedure when the hole is actually made despite the use of topical anesthetics. But the pain only lasts a few seconds.

It is also not unusual for the doctor to hit a blood vessel in the iris when performing an LPI. If this happens you may notice what looks like a red streak on the iris when you look in the mirror. The body will eventually reabsorb this blood within a week or so, it's nothing to be alarmed about.

Surgical Peripheral Iridectomy

Because the procedure is not invasive, antibiotic eye drops are not necessary. Most doctors will, however, prescribe a steroid eye drop such as Omnipred (generic name Prednisolone Acetate) to prevent any inflammation. Typically, only one eye is done at a time.

The peripheral iridectomy is a surgical procedure performed in a surgery center or hospital that involves cutting out a wedge-shaped section of the peripheral iris. This serves the same purpose as the YAG PI and is usually used after a failed peripheral iridotomy as a last resort.

Life After Treatment

If you are treated for narrow angle glaucoma with a YAG PI it’s important to have regular eye exams to make sure the PI remains patent, or open. Although rare, there is the risk that the PI will become occluded by cellular debris or pigment from the iris. If this occurs, the patient will experience an acute angle closure. For this reason, many doctors put in an extra PI to act as a “safety valve.” If one becomes occluded, it’s highly unlikely both of them will become occluded at the same time.

Remember to see your eye doctor if you suspect you have an eye problem. Seeing the ophthalmologist as quickly as possible can mean the difference between permanent blindness and a lifetime of clear vision. Don’t hesitate to call your ophthalmologist if you think something is wrong. If they won’t see you within 48 hours, it’s time to find a new doctor.

© Copyright 2012 - 2016 by Melissa "Daughter of Maat" Flagg ALL RIGHTS RESERVED

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Comments 9 comments

Pamela99 profile image

Pamela99 3 years ago from United States

This is an interesting article about glaucoma. I don't know of anyone in my family with this problem, so this was mostly new information for me. Very well written article.

Daughter Of Maat profile image

Daughter Of Maat 3 years ago from Rural Central Florida Author

Thank you Pamela, it's a tough topic to write, so for someone who has no experience with the topic to say that I wrote a good article means I did it right! Thank you!!!

ptosis profile image

ptosis 2 years ago from Arizona

OMG! Thank you for writing this!!!!!! I went to the eye doc and in one eye it's 14 & the other eye is 22. I go see the eye surgeon to see if I get the hot poke in the eye. Damn!!! It's gonna hurt?!?!?! I didn't think it would hurt. I thought there were no nerve endings.

Anyway. I starte crying in the eye doc and then I tried to calm myself done saying - it's only one eye, but it looks like they will do two, for good luck. Thanks.

I freaked out thinking about "A ClockWork Orange" with the eye springers and hot pokers warmed over the fire. Arrrrrhggghhh!!.

Thanks. I needed this article.

Daughter Of Maat profile image

Daughter Of Maat 2 years ago from Rural Central Florida Author

A pressure of 22 isn't narrow angle glaucoma. You are most likely going to be treated with Selective Laser Trabeculoplasty or SLT which treats primary open angle glaucoma. The SLT laser doesn't hurt at all normally because it only targets the trabecular meshwork of the eye, not the iris itself. Hope that helps

ptosis profile image

ptosis 2 years ago from Arizona

Thanks for writing back. Still totally freaking out. I asked Doc if constant crying did it and he said no. Worried about being worried.

No symptoms. 52 year old female 20/20 & 20/30 vision

Eye exam Jan 2014 measured eye pressure to be 15 and 22. Feb 2014 it was 14 in both eyes. Planned to have a Yag-Pi in April but canceled it and seeking second opinion advice since a dramatic drop in eye pressure is unusual.

surgeryencyclopedia; "The iridotomy can be a complete failure if don't have pupillary block but plateau iris. Many unnecessary iridotomies result in severe adverse effects of glare, white lines, double vision, permanent inflammation and IOP."

webeye.ophth.uiowa; “Plateau iris syndrome is uncommon but mostly seen in young adults."

On medhelp; “ ... glaucoma attack after the iridotomy, means cut-out iris debris obstructs the trabecular meshwork and often lead to uveitis. It's a surgery that should simply be avoided, because it has so many side effects and very seldom prevents a glaucoma attack. It more often provokes it.”

On ncbi.nlm.nih; “Patients who have LPI are at greater risk of requiring therapy to control IOP, even if they have a successful procedure. ... Yag-pi increases the frequency of having cataracts. .. Exfoliation syndrome, is vastly under-diagnosed and could explain a rise in IOP after an an iridotomy.

Nika 5 months ago

Thank you Melissa for this extremely helpful article. My mom was recently diagnosed with very shallow Anterior Chamber both eyes and recommended cataract surgery to alleviate the same. Eye pressure was 14 and vision is good with glasses. She is 68 yrs, hyperopic, and generally in good health. We are getting one eye cataract surgery done this week. Do you have any words of advice or caution? The diagnosis was a surprise and I feel we panicked and rushed to schedule the surgery. Your input is much appreciated.

Kay 2 months ago

What allergy meds do I avoid with narrow angle glaucoma????

Daughter Of Maat profile image

Daughter Of Maat 2 days ago from Rural Central Florida Author

Your doctor should perform a peripheral iridotomy prior to cataract surgery since the eye needs to be dilated in order to be able to remove the lens. Removing the cataract will open the anterior chamber, but if the chamber is so shallow that dilating the eye will cause an angle closure, a PI (peripheral iridotomy) should be performed first. Hope that helps!

Daughter Of Maat profile image

Daughter Of Maat 2 days ago from Rural Central Florida Author

Anything with pseudophedrine or phenylephrine in it.

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