What Does it Mean to have Narrow Angles and How is it Treated?
Friday, June 28th, 2019, 2:35 pm
Being told you have narrow angles at your doctor’s visit can be quite confusing, especially if this is the first time you’ve heard of it. Narrow angles is a term used to describe the anatomy of the eyes in certain people that is different from what we determine to be normal. The area between the front, clear part of your eye called the cornea and the colored part inside your eye called the iris is the anterior chamber angle. Fluid known as aqueous humor is constantly produced in the eye and this fluid flows around the pupil into the anterior chamber of the eye. The fluid is drained out of the eye at the “angle” through drainage channels called the trabecular meshwork.
Certain people have a slightly different eye anatomy in which the iris is located very close to the drainage channels of the eye causing the angle to be narrow. Narrow angles tend to be more common in people who are farsighted because they have shorter eyes than those who are nearsighted or don’t need glasses at all. Having shorter eyes means that there is less room in the front of the eyes to contain both the lens and the iris. Because things are more crowded in the area, the iris gets pushed forward and causes the angle to narrow. It is also more common in people over 60 as the anatomy of the anterior chamber of your eyes changes with age, particularly through narrowing of the angles. Women tend to more commonly have narrow angles than men and also people of East Asian or Eskimo descent in comparison to other ethnicities. Narrow angles also run in the family so if you are found to have narrow angles, it is likely someone in your family also does.
Everytime you attend an eye doctor’s appointment, the ophthalmic technician that first examines you is trained to check if you appear to have narrow angles. This is important to do before we put in drops in your eyes to dilate your pupils, as people with narrow angles should not undergo pupil dilation before the narrow angles are corrected. Dilating the pupils further closes the space in the anterior chamber angle and could potentially completely close the angle. At your eye appointment at Skouras Eye and Cosmetic Centre, if the ophthalmic technician, after doing your initial examination, suspects you may have narrow angles, he/she will forego the dilation drops and make sure you are seen by Dr. Skouras regarding this concern. Dr.
Skouras will then take another look at your eyes and perform a test called a gonioscopy to confirm whether you do indeed have narrow angles and whether a laser procedure will be
necessary to correct this. A gonioscopy test involves positioning your head in the slit lamp and having your eyes examined under light from the other end by the ophthalmologist, as you normally do at eye examinations. However, for this test, Dr. Skouras will also use a special contact lens prism covered in an anaesthetic gel to make sure you don’t feel any discomfort. The prism is placed directly on your eye and a small beam of light is used to illuminate and visualize your eyes in more detail, particularly the anterior chamber angle and drainage system. While your eyelids may feel some pressure from the lens, it is typically a painless test and only takes a few minutes to do. This test allows Dr. Skouras to: 1) confirm whether you have narrow
angles and 2) judge whether treatment will be necessary.
People with narrow angles are at risk of angle closure which would prevent fluid from draining normally and cause pressure to build up in the eye. This can cause damage to the optic nerve and ultimately vision loss. Angle closure can either occur gradually over time or suddenly. Angle closure that occurs gradually causes the eye pressure to build up slowly over time, known as chronic angle closure glaucoma. This does not present with any symptoms, so you wouldn’t know you had it until you had your eyes examined, but it is still damaging to your vision if left undetected. If angle closure occurs suddenly, the pressure in the eye can rise to dangerous levels within hours. The increased pressure causes the iris to be pushed forward and block the drainage system completely. This is known as acute angle closure glaucoma, which is a medical emergency. It can present with sudden, severe eye pain, headache, blurred vision, red eye, nausea and vomiting and/or halos around lights. If the pressure is not relieved within a few hours, there may be permanent vision loss. Acute angle closure glaucoma is treated with an emergency laser procedure called a Laser Peripheral Iridotomy.
A Laser Peripheral Iridotomy is also performed as a preventive treatment in people with eyes at risk for angle closure glaucoma i.e. people with narrow angles. Not all people with narrow angles need to be treated as not everyone will get acute angle closure glaucoma. At Skouras Eye and Cosmetic Centre, we provide patients with a comprehensive eye examination and advanced tests and imaging to assess your risk for acute angle closure glaucoma. If you have narrow angles but are at low risk of acute angle closure glaucoma, you will likely be monitored over time to follow the progression of the anterior chamber angle. For those patients deemed to be high risk, Dr. Skouras performs laser peripheral iridotomies at the earliest convenience as an outpatient procedure within the clinic. The procedure involves using a laser beam to create a small hole in the iris of the eye. The hole is not visible to you or other people, except for your eye doctor upon examining your eyes under the slit lamp. The purpose of this hole is to create a permanent passage for fluid to flow into the anterior chamber of the eye, pushing the iris backward and thus widening the angle and unblocking the drainage channels. The procedure is safe, relatively painless except for the sensation of a zap or sting, and only takes a few minutes. The main risks of the procedure are that it may cause a small blood vessel in the iris to bleed which usually resolves on its own, or inflammation of the eye which may require the use of steroid drops for a few days after the procedure. Occasionally, the eye pressure may rise immediately after this procedure which is easily managed with eye drops for a few days to bring the pressure back down. Also, in certain cases where the iris may be difficult to penetrate, usually in people with dark brown eyes, it may require more than one treatment. A small number of patients report seeing flashes due to extra light entering through the new opening which may be distracting at first but eventually, it is not noticeable.
In addition to a detailed examination and gonioscopy, Dr. Skouras recommends that patients with narrow angles undergo anterior segment optical coherence tomography (AS-OCT)
imaging. AS-OCT imaging allows us take detailed cross-sectional images of the anterior segment of your eyes and precisely measure parameters such as the width of the angle,thickness of the iris and anterior chamber depth. These measurements are repeated in different lighting conditions allowing us to visualize dynamic changes in the anterior segment anatomy. The AS-OCT does not involve any direct contact with your eyes and takes approximately 10 minutes to complete. The procedure requires you to focus on a target light in both light and dark conditions while a technician takes measurements of the angle. Dr. Skouras will then compare the images and measurements taken before and after the laser iridotomy to evaluate the extent and effectiveness of the treatment in widening your anterior chamber angles. The AS-OCT is a useful adjunct in the diagnosis and treatment of narrow angles.
Tags: eye exam, glaucoma, ophthalmology
Category: General Eye Care