Glaucoma refers to a group of eye disorders that can result in the progressive damage of the nerve that connects the brain and eye. This nerve is known as the optic nerve. Individuals with this particular eye condition can lose their vision as a result of lost nerve tissue.
The optic nerve is actually a cluster of roughly one million individual nerve fibers that transfers visual signals to the brain from the eye. Primary open-angle glaucoma, which is the most common type of glaucoma, consists of an increase of fluid pressure within the eye. The boost in pressure can result in the loss of nerve fibers and progressive harm to the optic nerve. Blindness can also occur with advanced glaucoma.
All individuals with increased eye pressure will not necessarily end up developing glaucoma, and some individual with normal pressure in the eye will develop glaucoma. Once this pressure builds up too high within the eye for a specific optic nerve, regardless of what hat pressure management could be, glaucoma could develop.
Glaucoma is known as the second-leading cause of blindness in the United States. Generally, it occurs in individuals who are over 40 years of age, although there is an infant type of glaucoma that exists. Individuals with a family history of this eye disorder, African Americans over 40 years of age, and Hispanics over 60 years of age are more at risk of developing the eye condition. Some additional risk factors include chronic eye inflammation, corneas that are thinner, and taking drugs that could increase eye pressure.
Primary open-angle glaucoma, which is the most common type of glaucoma, tends to develop at a slow pace and often with no symptoms. Many individuals aren’t aware that they even have the eye condition until they end up with substantial vision loss. At first, glaucoma impacts peripheral (aka side vision), though it is possible for it to advance to the loss of central vision. If it is left unaddressed, glaucoma can result in substantial loss of vision in both of the eyes and could even result in blindness.
Acute angle-closure glaucoma, which is a lesson common form of glaucoma, tends to occur suddenly as a result of a quick increase in eye pressure. The condition’s symptoms can include nausea, eye redness, serious eye pain, seeing colored rings or halos around lights, as well as blurred vision. It is an emergency condition of which severe loss of vision may occur rapidly; therefore, it is imperative that you immediately see your optometrist.
Currently there is not a cure for glaucoma. However, if glaucoma is diagnosed and treated early on, it can typically be controlled. Medication and/or surgery can be used to slow down or prevent further loss of vision.
However, if vision has already been lost as a result of glaucoma, it is unable to be restored. For that reason, the American Optometric Association (AOA) recommends that individuals who are at risk for developing glaucoma undergo a dilated eye examination once per year. In some cases, it may be recommended for you to undergo more frequent examinations.
What Exactly Causes Glaucoma?
There are a number of theories out there about what causes glaucoma, but the actual cause is still unknown. While the disease itself has been linked to increase fluid pressure within the eye, there are other theories that include lack of blood supply to the optic nerve. Here are a few types of glaucoma and the possible causes:
- Primary Open-Angle Glaucoma – This is the most common kind of glaucoma, and with it, the damage that occurs to the optic nerve is painless and slow. Individuals who are impacted can lose a significant portion of their vision before any symptoms present themselves. One theory about the way this type of glaucoma develops is that the drain system of the eye becomes inefficient over a period of time, and as a result, an increase in fluid and buildup of pressure occurs inside the eye. An additional theory about this type of glaucoma is that there is inadequate blood flow to the optic nerve. Of course, there are other theories as well.
- Angle-Closure Glaucoma – This is a lesson common type of glaucoma, but it is considered a medical emergency that can result in loss of vision within just a single day of onset. This type of glaucoma tends to occur once the angle of drainage within the eye becomes blocked or closes. Many individuals who develop angle-closure glaucoma have incredibly narrow drainage angle. With age, the eye lens gets larger, which pushes the iris forward, narrowing the space between the cornea and iris. With the narrowing of the angle, the eye fluid is blocked from draining properly. As a result, there is a buildup of fluid and an increase in eye pressure. This type of glaucoma can be acute (which means that it suddenly appears) or chronic (which means is gradually progresses). The acute kind occurs when fluid drainage is blocked completely by the iris. When an individual has a narrow drainage angle and gets their pupils dilated, the angle could close and result in a sudden increase in their eye pressure. While an acute attack generally only impacts one eye, there is a chance that the other eye could be at risk as well.
- Secondary Glaucoma – This form of glaucoma occurs as a result of another eye disease or an injury. It can be caused by many medical conditions, drugs, eye abnormalities, and physical injuries. Rarely, surgical intervention can result in a secondary glaucoma.
- Normal-Tension or Low-Tension Glaucoma – With this particular type of glaucoma, pressure within the eye remains “normal,” though the optic nerve remains damage. Currently, there is no explanation for this. Maybe individuals with low-tension glaucoma have an optic nerve that is abnormally sensitive, or they have could have a reduced supply of blood to the optic nerve that is a result of a condition known as atherosclerosis, which is the hardening of the arteries. Under circumstances like this, even normal pressure on the nerve could result in damage.
Glaucoma Risk Factors
There are certain factors that an increase one’s overall risk for developing glaucoma, such as the following:
- Age – Individuals who are over 60 years of age are at an increased risk of glaucoma. However, African Americans find themselves at this increased risk after 40 years of age. With each year, the risk of developing this disease slightly increases.
- Race – African Americans are much more likely to develop glaucoma than Caucasians as well as being significantly more likely to sustain permanent loss of vision. Individuals of Asian descent as well as Native Alaskans are at an increased risk of angle-closure glaucoma. Individuals of Japanese descent are at an increased risk of developing low-tension glaucoma.
- Family History of the Disease – If you have a family history of the disease, you are at an increasing risk of developing it.
- Medical Conditions – There are studies that show certain medical conditions like high blood pressure, heart disease, and diabetes may increase the overall risk of glaucoma development.
- Physical Eye Injuries – Severe trauma like getting hit in the eye can cause an immediate increase of pressure in the eye. Internal eye damage can result in future pressure increases as well. In addition, eye injuries can cause the lens to dislocate, which can result in the drainage angle closing and increasing pressure.
- Other Eye-Related Factors of Risk – Certain eye anatomy features, specifically sensitivity of the optic nerve and thinner corneas, can be indicative of a higher risk for glaucoma development. Conditions like eye inflammations, eye tumors, and retinal detachments could potentially trigger glaucoma. There have been some studies that suggest higher amounts of nearsightedness could be a potential risk factor for the disease.
- Corticosteroid Use – The use of corticosteroids like hydrocortisone, prednisone, and cortisone for prolonged time periods may put some individuals at a higher risk of developing secondary glaucoma.
How Can Glaucoma Be Diagnosed?
A comprehensive eye exam is used to diagnose glaucoma. Due to the fact that glaucoma is a progressive eye disease, which means that it gets worse over time, an altercation in the optic nerve’s appearance, a loss of the nerve tissue, and a loss of vision can be enough confirmation of the diagnosis of glaucoma. Some of the optic nerves could resemble nerves with the disease, but individuals may not have any other signs or risk factors of glaucoma. These individuals need to undergo comprehensive eye exams for close monitoring of changes. Testing of glaucoma includes the following:
- Patient History – This is used to determine the symptoms that are being experienced and whether there are general health concerns and if family history that could be contributing to the issue.
- Visual Acuity Measurements – This is used to determine whether vision is being impacted.
- Tonometry – This is used to measure the eye pressure to detect any increased risk factors for the disease.
- Pachymetry – This is used to measure the thickness of the cornea. Individuals with thinner corneas are at a higher risk of developing the disease.
- Visual Field Testing – Also known as perimetry, this is used to determine whether the field of vision has been impacted by the disease. The test measures the central and peripheral (side) vision by either determining sensitivity to targets besides light or the dimmest amount of light that can be perceived in multiple locations of vision.
- Evaluation of the Eye’s Retina – This is used to monitor changes over a period of time and can include scans or photographs of the optic nerve.
- Supplemental Testing – Possibly including gonioscopy, providing a view of the angle anatomy, where the fluid drainage of the eye occurs. Serial tonometry is another test option and is used to obtain multiple measurements of pressure over a period of time looking for eye pressure changes. Also, devices are often used to measure the thickness of the nerve fiber and look for loss of tissue on certain areas of the nerve fiber layer.
How Can Glaucoma Be Treated?
Treatment of glaucoma is focused on reducing eye pressure. The most common form of treatment is prescription eye drops, and this is usually the first method of treatment. In some cases, systemic medications or laser treatment may be necessary. Currently, there is not a cure for the disease, but eyesight can be preserved with early diagnosis and regular treatment.
- Medications – Currently, there are many different types of medications that can be used to treat glaucoma. Generally, medications can help reduce the increased pressure within the eye. One medication or a combination of them can be prescribed. The type of medication can be changed if it is not reducing the pressure in the eye enough or if the individual is experiencing adverse side effects.
- Surgery – Surgical procedures may include laser treatment, inserting a drainage valve, creating a drainage flap, and destroying the tissue that is responsible for creating fluid within the eye. All of these surgical procedures work to minimize the pressure within the eye when medication is not doing the trick. Keep in mind, though, that surgery is unable to reverse loss of vision.
- Laser Surgery – Laser trabeculoplasty assists with the drainage of fluid from the eye. A high-beam laser stimulates the structure that is responsible for draining the fluid from within the eye, helping the fluid drain better. The results can sometimes be temporary, and subsequent procedures may be necessary down the road.
- Conventional Surgery – If prescription eye drops and laser surgery do not work, a trabeculectomy may be necessary. This microsurgery produces a drainage flap, which allows fluid to percolate in the flap and then drain into the vascular system.
- Drainage Implants – This type of surgery is often an option for adult individual who have uncontrolled or secondary glaucoma or for children with the disease. With this surgery, a small silicone tube is implanted into the eye to assist with the fluid drainage.
Acute Angle-Closure Glaucoma Treatment
This type of glaucoma is considered a medical emergency. Individuals who are impacted by this type of glaucoma can take medication to help minimize the pressure within the eye as quickly as possible; however, it is likely that they will need to undergo a laser surgery known as laser peripheral iridotomy as well. With this procedure, a laser beam produces a small hole within the iris so that fluid can flow much more freely toward the front chamber of the eye, which is where it will then be able to drain.
As previously mentioned, there is no current cure for glaucoma. Individuals who have the disease will need to continue to undergo treatment for the remainder of their lives. Due to the fact that the disease can change or progress with no warning, it is important to comply with eye medications and undergo routine eye exams. It is also possible that treatment may require periodic adjustment.
Maintaining control of eye pressure can help to slow or even stop harm to the optic nerve and continued vision loss. Your eye doctor may aim to lower eye pressure to a specific level that is least likely to create further damage to the optic nerve. This level is generally referred to as the target pressure and is generally a range as opposed to a single number. Now, the target pressure is different for every individual, and it depends on a number of factors, including the extent of the damage. Over time, it is possible for the target pressure range to change. New medications are continuously being developed to help combat glaucoma.
Early detection, quick treatment, and continuous monitoring continue to be the best ways to control glaucoma and minimize the changes for loss of vision.