Glaucoma is a serious disease of the eye that requires medical treatment. Many people have heard of glaucoma, but they often don’t know much about it. While many textbooks are dedicated exclusively to glaucoma, this article discusses the disease, its causes, symptoms, and other commonly asked questions to demystify glaucoma.
How Does Glaucoma Work?
Glaucoma is a permanent, progressive disease of the eye characterized by thinning of the optic nerve. Your optic nerve is the “cable” that connects the eyes to the brain and is responsible for transmitting visual signals to the portion of the brain that allows us to see.
In the human eye, we all have fluid (called aqueous humor) that naturally circulates and then drains through the “angle” of the eye. When this fluid does not drain properly, the eye’s pressure can increase.
Why is this increased eye pressure a problem? In general, increased pressure in the body, like elevated blood pressure, is a sign of concern. In this case, an increase in eye pressure can lead to optic nerve damage, potentially leading to blindness. However, there are several causes and still many unknowns about the disease.
Not all patients with glaucoma have high eye pressure; however, eye pressure can be managed with medication and surgical procedures, so it is an essential part of treatment.
What are the types of Glaucoma?
There are several classifications and forms of glaucoma, but the more common types will be discussed below.
Open-angle glaucoma is the most common form of glaucoma in the United States, and 2.7 million Americans have been diagnosed with this form. In this type of glaucoma, the eye’s drainage angle is considered “open.” An open angle means the natural anatomy of the eye does not obstruct it. However, the aqueous still does not properly flow through the eye, leading to the symptoms discussed below.
In closed-angle glaucoma, the eye’s drainage angle is narrow, leading to an increase in eye pressure. This can be thought of as similar to a sink with smaller pipes; the natural anatomy (narrower angle) leads to poor drainage. As you know from your physics class in high school, if the same volume tries to pass through a smaller opening, the pressure will increase to compensate. The same thing happens here.
In this form of glaucoma, the pressure of the eye is relatively normal (below 21 mmHg), but glaucomatous damage to the optic nerve is still seen. While this is thought to occur due to issues with blood flow to the optic nerve, more research is still being done to pinpoint the exact cause.
Pigment dispersion glaucoma
In this less common form of glaucoma, pigment from the iris gets rubbed off and clogs the drainage angle of the eye. This can be thought of like small chunks of your sink chipping off and slowly clogging it and causing poor drainage.
The structures in and around the eye are microscopic, so even small portions of pigment can clog the drainage system and cause poor drainage and increased pressure.
This form of glaucoma occurs due to trauma to the eye that damages the drainage angle of the eye. You can think of automobile accidents, blunt force trauma, or other blows to the head.
Neovascular glaucoma occurs when blood vessels grow over the drainage angle of the eye, blocking it. The blood vessels are always secondary to pathologies like diabetes or high blood pressure. This essentially means that our bodies essentially triage and prioritize which ailments to fight first, even if it may be to the detriment of our eyes.
What are the symptoms of Glaucoma?
Glaucoma earned its nickname as the “silent blinder” because of the devastating effects it can have over extended periods. Most patients experience slow, incremental, painless vision loss. More specifically, glaucoma usually causes a reduction in the side (“peripheral”) vision of a patient.
Eventually, in severe cases, a patient will experience total blindness or tunnel vision – where only a small amount of central vision remains. To stimulate tunnel vision, look through a paper towel roll to understand how much vision is left in end-stage glaucoma.
The lack of significant symptoms in the early stages is part of what makes glaucoma so serious and what makes early intervention critical. Unlike other diseases that may present uncomfortable symptoms like pain or shortness of breath, glaucoma starts with minimal signs.
Some patients with closed-angle glaucoma, however, will experience more noticeable symptoms. Acute angle-closure occurs when the eye’s drainage angle suddenly becomes backed up (usually due to the iris), and the pressure of the eye increases very quickly. These symptoms include headache, eye pain, blurry vision, nausea, rainbows around lights, and vomiting. Immediate presentation to your eye care provider is warranted if you are experiencing any of these symptoms.
Patients with pigment dispersion glaucoma may also experience symptoms of blurry vision more noticeable after working out, as it is thought that vigorous exercise causes more pigment to rub off the iris.
How is glaucoma diagnosed?
Diagnosis of glaucoma often takes several visits to your optometrist or ophthalmologist unless there is significant optic nerve damage.
There are several components that go into a test to diagnose glaucoma. Your eye doctor will take your eye pressure and dilate you and take a careful look at your optic nerve to assess it for any thinning. They will also use a specialized instrument to take a photo of the optic nerve to take a quantitative measurement of the amount of tissue remaining in the nerve. This is very useful for tracking the progression of glaucoma as well. Your doctor may also measure the thickness of your cornea (the clear front part of the eye) because patients with thicker corneas have higher eye pressures.
They may also perform a visual field, which is a test to determine the extent of your peripheral vision. This can help determine the stage of glaucoma and how much damage there is to the side vision. Usually, loss of vision occurs after significant optic nerve damage has already begun.
Another test done to diagnose glaucoma is a procedure called gonioscopy. This involves placing a small lens on the eye to assess the drainage angle of the eye. This is more helpful in classifying the type of glaucoma a patient may have.
How is glaucoma treated?
Treatment of glaucoma depends on the form of glaucoma the patient has, but pressure-lowering drops are the most common first-line treatment for open-angle and pigment dispersion glaucoma.
Your doctor will prescribe these drops to be used one to three times a day. Some of these drops cause side effects like burning, changes in eye color, changes in the heart rate, and blurry vision. Talk to your doctor if these become intolerable so that modifications can be made. It is important to take all medication as directed because vision loss from glaucoma is irreversible. Non-compliance with taking drops for glaucoma is a leading cause for quicker worsening of the disease.
In cases where drops are not lowering the pressure quick enough, a laser procedure or surgery may be recommended to help further open the drainage structure of the eye and lower the eye pressure. “There have been many recent advances in glaucoma surgery with safer, less invasive procedures available to lower the pressure of the eye. It is important for patients to discuss with their ophthalmologist to find out which procedure would be most beneficial for them,” says Dr. Lindsay Dawson, a glaucoma surgeon at Washington Eye Physicians and Surgeons.
For neovascular glaucoma, treatment of the underlying systemic cause and injections of a medication that stops the signals for new blood vessel growth may be used.
There is currently no cure for glaucoma, only treatment methods aimed at slowing down vision loss and preserving usable vision for as long as possible. However, the management of glaucoma has improved dramatically over the past several decades, and advances continue to be made.
What are the risk factors for glaucoma?
Patients who are at risk for glaucoma are those who are
- Older (over 50)
- African-American, Native American, Hispanic or Asian
- Have a family history of glaucoma
- Have a history of steroid use
- A history of injuries to the eye
- Have a history of surgery that resulted in massive blood loss
- Have high eye pressure
- Large optic nerves
- Have thin corneas
- Have systemic issues like diabetes or high blood pressure
Unfortunately, most of these risk factors cannot be prevented, but staying healthy and avoiding steroid use are some ways to reduce your risk for glaucoma.
Frequently Asked Questions
Does glaucoma cause blindness?
If not treated, glaucoma causes irreversible vision loss and (in severe stages) blindness. Glaucoma is the leading cause of irreversible blindness in the United States.
Said differently, yes, you can go blind from glaucoma. Roughly 15% of people who suffer from glaucoma will become blind in at least one eye.
Can children have glaucoma?
In very rare cases, children can have glaucoma. This is due to improper development of the drainage structure of the eye, and symptoms include large, bulging cloudy eyes. Fortunately, the incidence of infantile glaucoma is exceedingly low, and it is easily detected in a pediatric eye exam. Glaucoma in childhood is almost always treated with surgery.
Is it possible for dogs to have glaucoma?
Just like humans, dogs can also have glaucoma. It is more prevalent in certain breeds, and the dog’s eye will look cloudy and have a watery discharge. Go to your veterinarian if you suspect your dog is having issues with their eyes, as the condition can be painful in dogs.
Do glasses help with glaucoma?
Sunglasses and glasses help to physically protect the eyes of patients. This is especially important if they only have one functioning eye. In addition, some people who suffer from glaucoma are more sensitive to light or aren’t able to adjust as easily between light and dark settings so sunglasses can help them adjust.
Does weed help improve glaucoma?
Contrary to popular belief, weed or marijuana is not an acceptable treatment for glaucoma. Weed has been proven to lower the pressure of the eye, but only temporarily (for a few hours). The amount needed to sustain a lower eye pressure would be damaging to the lungs and heart.
In short, marijuana for glaucoma does lower the pressure, but only for a very short period, so it’s not a sustainable/recommended treatment.
In conclusion, glaucoma is a complicated condition with many causes and treatments. Patients with glaucoma are at risk for permanent vision loss and should follow their doctor’s treatment plans and stay consistent with their follow-ups. This condition is being researched every day, and new information is constantly being discovered. Perhaps one day, the poor prognosis can be reversed, but for now: use your eye drops!
Dr. Morgan Jones is a Doctor of Optometry (O.D.) completing a residency in ocular disease. She has experience in diabetic research, along with several years of clinical research. Along with being a community outreach leader and an avid mentor and tutor, she enjoys educating outside of clinic. Dr. Jones has a B.A. in Biology from Texas A&M University.