What Is Glaucoma?
Glaucoma is a progressive eye disease that can cause vision loss. Currently affecting around 2% of the U.S. population, glaucoma is the leading cause of blindness among African Americans and the third leading cause among Caucasians. Glaucoma in its various forms causes higher than normal intraocular pressure, created by the intraocular fluid (also known as aqueous humor) filling the inside of the eye. The body continuously produces this fluid essential to eye function and health, while the eye’s natural drainage system normally removes any excess fluid buildup at about an equal rate. If the eye’s natural drains become blocked, however, the buildup of excess fluid leads to an increase in pressure that could over time permanently damage the optic nerve.
Types of Glaucoma:
There are different types of glaucoma:
This is the most common type of glaucoma, and is usually related to an inherited trait in which the eye’s drainage canals tend to become clogged. Patients with open angle glaucoma usually have little to no symptoms in the early stages of the disease. As it advances, though, a patient may begin noticing vision problems, beginning first with restricted sight in their peripheral or “side” field, a halo effect around bright lights, and a mild aching around the eyes.
Acute Angle Closure Glaucoma
This is caused by structural flaws within the eye (such as a shorter eye length that leaves less space between the iris and the drainage canal) or from the development of cataracts. In these cases, the iris or other structures can become pressed against a drain and block it off. Unlike open angle glaucoma, this type of glaucoma can result in a very rapid pressure increase that often causes severe pain.
In addition, there are secondary forms of glaucoma caused by other health conditions like diabetes or eye inflammation. Injury to the eye could also damage the natural drainage structures.
Any glaucoma-related vision loss is permanent, so it’s critical to detect elevated intraocular pressure early and take measures to control it for the remainder of a person’s life. Although a patient may not know they have elevated eye pressure, an ophthalmologist or optometrist can perform a simple test during a regular eye exam to detect it.
We recommend everyone over the age of 35 undergo an annual eye exam not only for overall vision health but to detect elevated eye pressure if present. We also encourage exams at any age for patients at high risk for glaucoma, including those with diabetes, extreme near-sightedness, a family history of glaucoma, or who are of African descent.
Glaucoma Treatment and Management:
Managing glaucoma requires keeping intraocular pressure at a normal level for the rest of a patient’s life. The most common way and often the first treatment choice is with medicated drops a patient applies to their eyes daily. Depending on the active ingredients, these drops either help the eye drain excess fluid or decrease fluid production.
Eye drops are non-invasive, easy to use and can effectively control pressure for many years. Some patients, however, can develop allergies to the medication, or the drops become less effective over time, leading us to consider other procedures to lower eye pressure. One such common procedure is a trabeculectomy or filter surgery. During this procedure the surgeon removes tissue in the eye interfering with drainage, including part of the eye’s drainage system called the trabecular meshwork, to improve fluid removal. More recently we’ve seen the emergence of minimally (or micro) invasive glaucoma surgeries (MIGS). This new group of procedures include microscopic surgical techniques and specialized medical devices (like iStent®) that help increase fluid drainage, while running a lower risk of scar tissue development than a traditional trabeculectomy. Another new procedure in glaucoma treatment is selective laser trabeculoplasty (SLT) in which an eye surgeon directs laser energy at the eye’s drainage system. It is believed the quick beam stimulates the release of enzymes to that area of the eye that subsequently improves drainage.
Frequently Asked Questions:
What are the cause(s) for glaucoma?
In most cases, the principle cause for glaucoma is abnormally high pressure in the eye from intraocular fluid (intraocular pressure). Although we’re not sure about the exact reason for elevated pressure, it’s believed in most cases to be an inherited condition or related to certain environmental factors or systemic diseases like diabetes.
There are also different forms of glaucoma that may relate to its cause in an individual. Open angle glaucoma is the most common of these forms, and it usually stems from an inherited trait.
Angle closure glaucoma is usually caused by a defect in the eye such as a thickened cataract (a clouded eye lens) that may push the iris to block off the natural drain, possibly exacerbated by a shorter eye length. This can create an acute rise in pressure that may cause extreme pain, a differing experience from the usually painless open angle glaucoma.
There are also secondary forms of glaucoma triggered by other disease such as diabetes or eye inflammation. And some eye injuries could result in damage to the natural drain of the eye.
What are the symptoms of glaucoma?
Glaucoma in most cases is a “silent” disease, especially at the onset. Most patients won’t notice any glaucoma symptoms (unless it’s a specialized form of the disease) until it reaches an advanced stage.
An ophthalmologist or optometrist, however, can detect elevated pressure or other disease-related abnormalities during a routine eye examination. That’s why we recommend annual screenings for adult patients over thirty-five, with a family history of glaucoma or who are of African descent.
How is glaucoma tested?
Glaucoma screening is a normal part of any routine eye exam. Besides assessing overall vision, the eye doctor will measure the level of intraocular pressure with specialized equipment. He or she may also view the optic nerve with an imaging device to assess its health or to detect any abnormalities.
What is intraocular pressure?
Intraocular pressure is the pressure produced by the intraocular fluid within the eye. The eye creates and removes intraocular fluid normally at an equal rate. People with glaucoma, however, have a problem with removing excess fluid through their natural drainage system. This in turn causes the pressure to rise. Incidentally, it’s sometimes mistakenly equated with high blood pressure. But the two pressure measurements are separate and unrelated: in other words, you can have elevated intraocular pressure but not high blood pressure, and vice-versa.
Glaucoma vs. Cataracts
Medically speaking, glaucoma and cataracts are not related. Cataracts are a clouding of the lens that occurs in everyone at some point if they live long enough.
But in a certain subset of patients, a developing cataract can cause the lens to become thicker, which decreases the available space in the eye. This can force the iris to move in front of the drain and block it off, causing an acute pressure rise and severe pain symptomatic of angle closure glaucoma.
There’s also a large patient population who have both developing cataracts and open angle glaucoma. In these cases, removing the cataracts, even a little earlier than usual, might help lower the intraocular pressure. There are also medical devices available that can be installed during a cataract surgery that will further aid pressure reduction.
Are there any natural remedies for glaucoma?
There are no proven natural remedies currently available to treat glaucoma. The treatments that have proven most efficacious in reducing intraocular pressure are eye medicine drops, laser procedures for certain patients, and surgical procedures.
Are there any alternative treatments to medication drops?
We may consider other treatments if a patient can’t tolerate eye drops due to allergies or if the drops are no longer effective in reducing intraocular pressure. At that point we may assess a patient to see if they’re a good candidate for a laser procedure called selective laser trabeculoplasty (SLT), minimally invasive glaucoma surgery (MIGS) procedures, or filtration procedures like trabeculectomy (also known as a filter) or a tube shunt.
What is a trabeculectomy?
A trabeculectomy or filter procedure is a traditional glaucoma surgery used to lower the pressure in the eye. The surgeon creates a small flap on the sclera to remove a piece of the inner wall of the eye. This allows the fluid in the eye to bypass the dysfunctional natural drain and escape through a new pathway.
What is a laser trabeculoplasty?
Selective Laser Trabeculoplasty (SLT) is a non-invasive procedure used to treat open angle glaucoma. We direct laser energy at the natural drain of the eye in order to rejuvenate the system. It can help lower intraocular pressure for up to a few years, and if effective can be repeated.
What is a tube shunt?
A tube shunt is the most commonly performed traditional glaucoma surgery. A small tube is inserted into the eye and allows fluid to escape to a plate that is placed underneath the skin of the eye. The implant tube remains in the eye permanently to reduce pressure.
What are minimally invasive glaucoma surgeries (MIGS)?
MIGS are a new classification of glaucoma surgery. It’s an umbrella term referring to multiple procedures including iStent, CyPass or Kahook Dual Blade. Most of these procedures are done at the time of cataract surgery. They’re less invasive than the traditional glaucoma surgeries and therefore are associated with less severe complications. However, they’re usually not as effective. MIGS are good options for people with mild to moderate disease and have a co-existing cataract.
What is iStent?
iStent is a medical device that’s part of the family of MIGS pressure-reducing procedures. In effect, iStent is a trabecular meshwork bypass stent that’s placed in the natural drain of the eye at the time of cataract surgery. About the size of a letter on a penny, the stent helps reduce intraocular pressure by allowing the fluid to bypass the dysfunctional natural drain.
– Answers provided by: Adam Quinn, M.D.