Glaucoma is an ocular disease affecting the optic nerve in the back of the eye. The optic nerve carries the visual information from the retina of the eye to the vision center in the posterior area of the brain. If not detected, glaucoma will lead to permanent blindness. Glaucoma’s nickname is the “thief in the night”.
Most types of glaucoma do not cause any recognizable symptoms. In over forty years of practicing ophthalmology, no one has ever come into my office and complained that they were losing their side vision and may have glaucoma. I have seen many people with vision loss from glaucoma, but none came into my office complaining of vision loss. Until the end stage of glaucoma, it does not cause any blurred vision. Glaucoma slowly takes away the side vision over months and years of time. If you lose some side vision slowly, you adjust to the loss without knowing. You turn your eyes and head more to compensate for any side vision loss. In most cases, glaucoma does not blur the vision until the end.
Glaucoma is the second leading cause of permanent blindness in the world. Glaucoma most often impacts people over the age of sixty. One out of every 10,000 babies born in the United States has congenital glaucoma. Several famous people have been born with congenital glaucomas, such as Stevie Wonder, Ray Charles, and Andrea Bocelli, to name a few. Approximately three million people have glaucoma in the United States.
Glaucoma does have a genetic component. Several genes for developing glaucoma have been identified. African Americans are six to eight times more likely to develop glaucoma. More than sixty-five million people in the world have glaucoma.
Glaucoma does not have a cure. It can be managed with medications, laser surgery, and traditional surgery. It is vital that a person with glaucoma be monitored closely. Any vision loss from glaucoma is lost forever.
Anyone with a family history of glaucoma must be checked to see if they have it. If they are over age forty, they should have their eyes checked on a yearly basis.
What is Glaucoma?
Glaucoma is a multifactorial disease of the optic nerve caused by a combination of genetic factors, vascular risks, anatomical structure, and immune responses. Risk factors for developing glaucoma are being over sixty years of age, family history, race, a thin corneal thickness of fewer than 500 microns, diabetes, myopia, steroid use, and a prior history of an eye injury. There is a new association of glaucoma related to sleep apnea.
There are two major categories of glaucoma: primary glaucoma and secondary glaucoma.
Primary glaucoma or idiopathic glaucoma has no identifiable cause. It is divided into two groups, which are open-angle glaucoma and closed-angle glaucoma.
Open-angle glaucoma is classified into primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG).
In primary open-angle glaucoma, the intraocular pressure is elevated, causing damage to the optic nerve.
In normal-tension glaucoma, the eye pressure is not elevated, but there is still progressive damage to the optic nerve.
Angle-closure glaucoma is divided into two types: acute primary closed-angle glaucoma and chronic angle-closure glaucoma.
In acute angle-closure glaucoma, the angle and space between the iris and the cornea are narrow. At the end of the angle is the trabecular meshwork which the fluid produced in the eye must use to flow from the eye. If there is no space or channel for the fluid, the eye pressure will suddenly rise to a very high level. This high pressure can damage the eye very quickly.
In chronic angle-closure glaucoma, the angles close intermittently with temporary elevations of the eye pressure. Over time, scarring in the angle develops, leading to peripheral anterior synechiae. This further blocks the outflow of fluid from the eye.
Secondary glaucoma has an identifiable cause for the development of glaucoma. These causes may be secondary to medications, injuries, and eye diseases.
Symptoms of Glaucoma
In the early stages of the most common type of glaucoma, there are no symptoms. As glaucoma advances, symptoms include loss of side vision, dim vision, eye fatigue, glare, tunnel vision, eye discomfort, and blurred vision.
In acute angle-closure glaucoma, symptoms include pain that can be severe in and around the eye, blurred vision, fixed and mid-dilated pupil, nausea and vomiting secondary to the severe pain, and a red, inflamed eye.
What Causes Glaucoma?
In open-angle glaucoma, the trabecular meshwork inside the eye, which the fluid produced in the eye must travel through to exit the eye, becomes partially clogged. The fluid has difficulty exiting from the eye into a vein in the eye. The elevation of eye pressure from the backed-up fluid damages the optic nerve in the back of the eye over time. The higher the eye pressure, the faster there will be vision loss.
In angle-closure glaucoma, the angle between the iris and the cornea inside the eye is too narrow and the iris can come in contact with the cornea, totally blocking the drainage system. This is like putting a stopper in a sink and no fluid gets out. The eye pressure rapidly increases to a very high level inside the eye, causing the symptoms related to angle-closure glaucoma. This is a medical emergency related to the eye and needs immediate treatment. There can be extensive permanent vision and damage to the structures inside the eye.
In secondary glaucoma, medications, ocular inflammation, or other eye diseases disrupt the flow of fluid from the eye. The underlying ocular disease needs to be treated along with treating the increased eye pressure. Once the eye problem is treated, the eye pressure may return to normal and not require any treatment.
How is Glaucoma Diagnosed?
Initially, a thoroughly complete eye exam is performed, which includes measuring the intraocular pressure (tonometry) and a slit-lamp (microscope used to closely examine the eye) examination of the front of the eye. The angles are evaluated by gonioscopy using a lens with a prism to look into the angle of the front of the eye to determine its width. The corneal thickness may be measured, which is called pachymetry. After dilating the pupil, the retina and optic nerve are examined.
A description of the optic nerve is recorded, revealing whether there is any damage to the optic nerve from glaucoma. A visual field will be performed using a computerized machine to determine if there is any loss of peripheral vision from glaucoma.
An OCT will be used to evaluate the health of the optic nerve. It is a test that measures the number of nerve fibers entering the optic nerve. Any loss of nerve tissue will be documented by the OCT instrument. Photos of the optic nerve will be taken to monitor changes in the optic nerve from glaucoma.
Glaucoma Treatment Options
Once the diagnosis of open-angle glaucoma has been made, there are multiple treatment options available to successfully manage glaucoma. All of these treatments focus on decreasing intraocular pressure to prevent damage from occurring or stop any further damage that may have already happened. In most cases, the first line of treatment is eye drop medications that will lower eye pressure (IOP). Another option is a laser treatment that will lower the intraocular pressure, called selective laser trabeculoplasty or SLT. People with more advanced levels of glaucoma may need other procedures, such as minimally invasive glaucoma surgery (MIGS), MicroPulse laser therapy (MLT), and traditional glaucoma surgery procedures. Your eye surgeon will discuss the different options and help you decide which is the best treatment for you.
Acute angle-closure glaucoma treatment is surgical. The angle has closed, and no fluid can exit the eye. A laser iridotomy is performed to bypass the closed angle. An iridotomy is a small opening made in the peripheral portion of the iris. This lets the fluid directly enter the trabecular meshwork and open the angle. The laser procedure is very simple and takes only a few minutes to perform with only a numbing drop for anesthesia.
Secondary glaucoma involves treating the elevated eye pressure as well as the underlying disease that is causing the eye pressure to increase. Once the underlying illness is treated, the eye pressure may return to normal and not need treatment.
Glaucoma Diagnosis or Levels
The diagnosis of open-angle glaucoma is made when there is documented damage to the eye from glaucoma. A person may have elevated intraocular pressure but no damage to the optic nerve. In this case, the diagnosis is ocular hypertension. This person may need to lower the eye pressure to prevent any damage from occurring. The eye doctor will determine whether treatment is recommended to lower the eye pressure depending on the risk of damage. Another diagnosis related to glaucoma is open-angle low risk or open-angle high risk. This determination is made based on the number of risk factors an individual may have for developing glaucoma.
Glaucoma Treatment Goals
Based on the level of glaucoma and the risk factors present, the eye doctor will set a pressure or target pressure they believe will be safe for your eye and/or stop any further glaucoma damage. Your eye pressure and glaucoma tests will need to be monitored by your eye doctor. Depending on the severity and how well your glaucoma is being controlled, you will need to be seen by the eye doctor every three to six months. It is extremely important that you use your medications correctly and keep your appointments. Since you cannot feel or sense the level of your eye pressure and there are no symptoms of routine glaucoma, you need to always see your eye doctor when your appointment is scheduled. Any vision that is lost from glaucoma is permanent.
Dr. James E. Croley III is a respected eye surgeon and a Christian. He is the author of two books, Believing is Seeing and The Blinding of America. Order copies for your family and friends today.