Continuing from our previous discussion about glaucoma, we will now focus on closed angle glaucoma.
What is closed angle glaucoma?
Closed angle glaucoma, or angle-closure glaucoma, is when the angle of the eye is blocked or closed. The angle is the area formed by the iris and the cornea. The iris can be pushed forward to block this angle, which does not allow normal fluid in the eye to move properly. Angle closure can occur suddenly (acute angle-closure) or gradually (chronic angle-closure). Acute is considered a medical emergency. Glaucoma means that there is damage to the optic nerve which causes loss of peripheral vision.
How is closed angle glaucoma different from open angle glaucoma?
In open angle glaucoma, the position of the iris is normal and the angle of the eye is open. With closed angle glaucoma, the iris has moved or bulged forward closing off the angle, which results in more sudden symptoms. Closed angle is more rare than open angle glaucoma.
What puts people at higher risk of developing closed angle glaucoma?
- Older age
- Asian or Inuit background
- Family history
- Female gender
- Hyperopia (farsightedness)
What are the symptoms?
Since the angle is blocked very suddenly, the eye pressure can rise quickly. This can cause headaches, eye pain, blurry vision, and haloes around lights. Patients may also experience nausea and vomiting. Patients who have chronic angle-closure, may experience multiple attacks over time with milder symptoms. Without treatment, glaucoma will eventually lead to blindness.
How is it detected?
A comprehensive exam including checking the vision and the pressure are important if someone is having an attack of angle-closure. Doctors use a lens with mirrors to check if the angle is closed.
A dilated eye exam is important to see the optic nerve. This may be delayed in order to treat an acute episode of angle-closure.
When it is safe to do so, photos are taken to monitor the progression of the disease. This photo shows what a normal optic nerve looks like. The arrow points to the pale circle in the middle which is small in size.
The following photo shows an optic nerve that is damaged by glaucoma. The pale circle is much larger than the normal nerve. The arrows point to the edge of the pale circle.
In addition to monitoring the nerve on exam, doctors take a photo of the nerve to look deeper at the fibers that make up the nerve. As one gets older, it is normal to lose some of these fibers. With glaucoma, the fibers are damaged and lost more quickly. Optical coherence tomography (OCT) shows where the nerve has more damage due to the loss of these fibers. It shows the thickness of the retinal nerve fiber layer (RNFL).
This photo shows a healthy optic nerve. The nerve thickness is normal and is plotted in the green area.
The next photo shows that there has been damage from glaucoma. The nerve thickness is much lower than normal and is plotted in the red area.
Finally, doctors conduct a test to check the peripheral vision of patients to look for damage from glaucoma. When the optic nerve is damaged, the vision loss starts in the periphery and a formal visual field test is done to check this vision.
The next photo is a visual field of someone without glaucoma. The arrow points to the normal blind spot in the vision.
The following is a visual field of someone with vision loss due to glaucoma. The arrow points to the area where the patient is not able to see.
The exam and these tests should be done at least once a year to ensure that the disease is not progressing.
What are the treatments for closed angle glaucoma?
The goals in treating closed angle glaucoma are to keep the angle open, manage the eye pressure, and prevent any optic nerve damage.
Medications: During an acute attack, medicated eye drops are used to decrease the eye pressure and eye pain. There are several types of drops that work in different ways to lower the eye pressure. Some drops also come as a combination of two different medicines in one bottle. Oral medications and occasionally IV medications are needed to lower the pressure if drops are not enough. Some patients may need to continue taking medicated eye drops to control the eye pressures even after an acute attack.
Laser iridotomy: This procedure is the ultimate treatment and is performed in the eye clinic as soon as possible. It consists of making a very small hole in the iris. This allows the iris to stay in place and lets fluid flow naturally without being blocked. It is recommended that patients have this on the unaffected eye as well to lower the risk of an episode of angle-closure.
Surgery: When there is ongoing damage to the eye despite doing other treatments, surgery may be an option for treatment. It requires going to the operating room where the surgeon inserts a tube or valve in the eye to help the fluid flow more easily. This will then lower the eye pressure. In certain cases, cataract surgery is warranted to help open the angle.
Glaucoma can be a complex disease and requires an individualized approach for treatment. Please be sure to discuss with your doctor all options to ensure the best treatment plan for you.
Return next month for our next installment on glaucoma!
- Image courtesy of Nisha Gupta, MD [return]