Anatomically narrow angle (or narrow angle) is a relatively common finding on ophthalmic examination. Narrow angles become increasingly common as we age and can be diagnosed with gonioscopy in which a small contact lens is used to examine the eye.
The fluid drains from the eye at a location termed the "angle". The angle is the junction of the cornea (the clear front part of the eye) and the iris (the colored part of the eye).
As we age, the lens inside of our eye grows. The lens sits behind the iris and, because of the growth of the lens inside the eye, the angle tends to narrow as we age. This becomes important when the angle becomes narrow enough to allow the iris to actually touch the drain. Repeated touching can lead to scar tissue, which can lead to elevated intraocular pressure and predispose to glaucoma. This scenario is most common in people with hyperopia (farsightedness) because they have a slightly shorter than average eye leading to crowding of the structures inside the eye, however, it can occur in people with myopia (nearsightedness) as well.
Treatment generally includes placement of a microscopic hole in the iris using a laser in the office called laser iridotomy. Laser iridotomy is relatively painless and takes approximately 20 seconds to complete. The presence of this tiny laser hole allows fluid to circulate normally in the eye, thereby opening the angle and preventing scar tissue and elevation of intraocular pressure that can lead to glaucoma. In some cases additional laser is necessary to complete the opening of the angle.
Many patients with narrow angles discover the condition when they are undergoing a routine eye examination. They are often understandably alarmed and concerned with the diagnosis, particularly because they usually have no symptoms or complaints. Remember that a diagnosis of narrow angles is not the same as a diagnosis of glaucoma. Many people with narrow angles do not have elevated intraocular pressure with damage to their optic nerve consistent with glaucoma. While narrow angles can eventually lead to glaucoma, the early treatment and diagnosis of narrow angles can help prevent glaucoma, and treatment by a trained physician is relatively straightforward.
This article was written by Glaucoma Specialist Shani Reich M.D.
Park SB, et al. Assessment of narrow angles by gonioscopy, Van Herick method and anterior segment optical coherence tomography. Jpn J Ophthalmol. 2011.
This article reviews the use of gonioscopy (using a contact lens on the eye) to detect narrow angles and the need for laser iridotomy
Liebmann JM, Ritch R. Laser surgery for angle closure glaucoma. Semin Ophthalmol. 2002;17:84–91.
This article reviews the indications and techniques for laser iridotomy and laser iridoplasty in clinical practice.
In the picture here, you can see the laser is directed at the iris very close to the ciliary body. The purpose of applying the laser in this area is to allow for the fluid made by the ciliary body to have direct access to the trabecular meshwork where it drains from the eye. In the picture, you can see that the angle is still narrow but draining is occurring. In reality there is a change in the fluid flow and dynamics of the eye such that after laser the iris will actually move away from the cornea after laser, in most all cases.
The first step of having a laser is preparation. The patient will be consented for the procedure and then a drop will be placed in the surgical eye that will make the pupil very small. This medicine is called Pilocarpine. You may required only one drop or several over time to make the pupil fully small. The most common side effect of Pilocarpine is a mild headache above the eye being lasered. The vision will be slightly blurry due to making the pupil small. After the patient is ready, you will put your head into to the same slit lamp machine you do in the office during the regular visit. A laser will be focused on the iris and one or several shots of laser will be used to make the small hole. Most all patients feel nothing or minimal discomfort during the laser. Afterwards, the patient will be given prescription drops to take home and a follow up appointment to dilate the eye and check the laser. If the second eye is requiring laser then the second eye will be lasered, and a follow up appointment given afterwards.
In the picture here, you can see there are 3 different shapes to the eye. In the first picture, the angle is shown to be 45 degrees. What this means is that the angle formed between the cornea above and iris below is 45 degrees. In the second picture, the space is 20 degrees and in the 3rd its 10 degrees. The normal space has an angle of 40-45 degrees.
Let me first say that in my practice of 16 years, this is one of the number one reasons patients come to me for second opinions. The first thing I hear is that I didn't understand why I was getting the laser and the second part is "do I really need it?"
Let me first state that every physician has a different threshold for treating narrow angles with laser. I rarely ever see a patient that comes to me for a second opinion where lasering would be outright negligence, although sometimes I disagree with the need for it.
Here is how I look at it. After examining the angle of the eye if the angle is narrow to about 15 degrees or less, then I feel most all patients need the laser. There are a lot more things I look at when making my decision but for layman's terms, this is a good guide. There are tests that can be done to determine if angle closure will occur prior to laser. One such test is called the provocative test where we try to provoke a mild angle closure attack by placing the patient in a specified position or by using certain drops, or both. We can also ultrasound the eye's anterior segment.
For me this has gone by the wayside a bit because laying face down and getting a dilating drop will never occur in real life...like when in your life will you have a dilating drop placed into your eye and you just happen to be laying face down at the same time. For one you will almost never have a dilating drop handy in your home and there is no reason you would be taking it anyways.
So whom do you laser?
I laser anyone with an angle less than 16 degrees and also there are certain anatomical features in the eye to determine if the patient will more than likely go into angle closure.
My decision to laser is based on the aforementioned rule of less than 16 degrees. Also, I look at the patient's lifestyle. I also determine if the patient is planning to have cataract surgery in the near future and family history of narrow angles or angle closure glaucoma. Based on these factors, I'll determine if a patient needs a laser. Angle Closure never occurs when you're in the doctor's office, at this amazingly convenient time to occur. It happens when you're flying in an airplane and have no medical treatments available, while watching a movie and, or on a vacation and imbibing on your favorite liquor, or after taking a cold or allergy medicine. The reasons is that in all these events, the iris is drawn towards the cornea and slightly dilates the pupil making then angle closure event occur.
In my 16 years of experience, and likely performing or seeing patients with laser more than 1000's of times, I have found this procedure to have almost no complications. The most common effect from the laser is seeing a small shadow through the laser hole. Its rare for patients to see it and when they do most are not bothered by it. If they are bothered by it we have solutions. Retinal detachment is almost never seen. Inflammations after laser is almost 100% and that is why drops are given to resolve it. The inflammation is short lived and not bothersome to most patient's. Rarely the inflammation may persist for a long period of time. This is very rare.
If you are at risk and you don't treat, you may go into angle closure and have a full blown attack. This typically takes a normal eye pressure around 16 up to about 50-70. At these very high eye pressures blood can barely get into the eye and as a result you may lose enough blood flow to cause permanent vision loss. Full blown attacks are severely painful so much so that patients' will often vomit profusely.
On examination, I'll see the iris muscles become a lot weaker after an attack and we also see permanent vision loss if a fix doesn't happen right away. Remember this, that when the attack occurs, if you're in a plane you'll have to wait until you land to then first find someone that can treat you. This will be a disaster. In a foreign country or on a cruise ship, this may result in a very bad outcome.
Typically, this is what I see. A patient will develop severe pain in one eye, start vomiting or feeling very nauseous. Patient's may think or be told its a migraine. Uncertain of the problem, and usually with some delay the patient will eventually get to the emergency room. There it will take from as short as 20 minutes to as long as 4 hours before you are seen by a doctor and if they have eye pressure measuring equipment you might get a proper diagnosis. At that time, the ophthalmologist will be called if there is one on staff there and sometime 4-8 hours after the attack, that you will get a full treatment. As you can see this is a medical disaster first because the patient doesn't know what is happening and second because its not always easy to diagnose and treat this.
So when I weigh whom to treat, even though patients with narrow angles have a low probability of having a full blown angle closure attack, in general, the risk to the patient is too high to go on chance that it doesn't occur. I lean towards treatment even with a negative provocative test if the angle is less than 16 degrees because the risk of having treatment is minimal in good hands and someone experienced in laser, and the risk of not having it is a very painful and long and harsh experience if angle closure occurs and the patient could become permanently blind. Each patient I see we will have a full discussion tailored to them and we will make a decision together.
How long will I take the post laser drops?
Typically one week. There is usually two kinds given, but there are exceptions to this.
Will I see a shadow after the laser?
This can occur but is rare and very easy to treat in most circumstances.
Will I need to come back after laser?
Yes. Always schedule an appointment afterwards within a few weeks.
Where is the best placement for the laser on the iris?
Most physicians typically place them between 10-1 or 3 or 9 o'clock. All 3 areas have great success. We've found that placing them around 3 or 9 o'clock leads to less glare or shadows being seen. The goals is to get a clean laser, and the doctor will specifically look for the best place to laser, and the placement is secondary.
Can it come back even after the laser?
Yes. While the laser is the best non-surgical treatment, it can. In that case you would need to have your natural human lens removed for a definitive treatment.
Can anything else cause narrow angles besides aging and being hyperopic?
There are many drugs when taken orally or IV can cause the iris to move forwards toward the cornea. Make sure you have a full list of medicines that you take when discussing your eye conditions with your doctor. I recommend you hand them a full written list when coming in and not going by memory.
If I'm at risk of angle closure what's my chances of having a full blown attack?
In reality, the risk is relatively small and that's why I get so many patient's coming to me for a second opinion. My decision making is based on the anatomy of the eye and what would happen if it occurs in this patient balanced against the risk of the laser. Realize the risk of the laser is very small and so I'm mostly leaning towards laser over not, controversial cases.
Which way to do you lean when deciding to do the laser?
Remember, that if a doctor can't put into writing that something won't occur then that means their confidence is not so high. When I look at any condition I look at two things, the outcome of a false negative versus a false positive. What does this mean?
What it means is that if you have a false positive, you did not have the condition, or in this case would not go into angle closure, but was treated anyways.
In a false negative, you had the condition or went into angle closure but were not treated.
So what does this all mean? Simply, if you have something that could harm you seriously if you don't treat and the treatment is low risk, you treat. If you have something that can't harm you then you don't treat.
Doctor, I still don't understand. Explain it to me like I'm 10 years old.
Sure. Let's say you have a cataract and 5 doctors tell you to operate and 5 tell you not to. What do I recommend? I recommend not to...Why? Because cataracts can be fixed at any time, they don't ever cause permanent vision loss and if you're not bothered by them, and your vision is good, there really isn't much to worry about. It can always be removed at a later time.
Let's take Narrow Angle Glaucoma or Glaucoma, in general. Its can cause permanent vision loss, failure to treat timely can result in a painful and horrible experience in the case of narrow angles, and the risk of treatment is very low. 5 doctors say you have it and 5 don't. I treat because the risks from treating is low and the risk of not treating is very high. Its great to be academic in your practice of medicine but medicine is just as much an art as it is a science and you can't just go by the "studies", and we're not so brilliant at predicting the future. Good doctors, when making decisions, must use a bit of practicality and tincture of discretion, and a spoonful of experience.