Glaucoma is an insidious eye disease because of its gradual onset without really causing any visual disturbance to the patient. The term Glaucoma describes a number of eye conditions that result in permanent damage to the optic nerve. Generally, Glaucoma is thought of as a higher than “normal” Intraocular Pressure (IOP). Although a high Intraocular Pressure is often a major cause of Glaucoma, it is not the only cause of Glaucoma. In fact, there are many different types and causes of Glaucoma. Regardless of the type or cause of Glaucoma, if it is left untreated, Glaucoma will cause permanent vision loss and possibly even blindness.
There are approximately 35 million people Worldwide who have been diagnosed with Glaucoma and another 15 million who probably have Glaucoma, but have not yet been diagnosed because they do not have access to eye care or even Glaucoma screenings. In the Western World Glaucoma is considered the second leading cause of blindness.
Glaucoma is so threatening because of its slow and progressive onset that does not cause patients to experience any visual symptoms or discomfort. Patients can walk around and not know that they are gradually losing their vision.
Glaucoma is best found and diagnosed during routine comprehensive eye examinations. However, Glaucoma can usually be detected by screening eye examinations. At a minimum, anyone over the age of 50 years old should be screened for Glaucoma every two years. If there is any family history of others having Glaucoma, patients should be screened every year beginning at 40. According to the Nottingham Glaucoma Study (http://bjo.bmjjournals.com/cgi/content/abstract/90/1/59), siblings of Glaucoma patients are at particularly high risk for developing Glaucoma by the age of 70 and should be repeatedly screened on an annual basis.
Causes & Types of Glaucoma
The ciliary body- a structure located inside your eye behind the colored part (the iris) produces a constant supply of a clear fluid. This fluid-the aqueous humor-supplies oxygen and nutrients to the tissues in the eye. Normally, the aqueous humour is drained through a meshwork of tissue that is located at the base of the iris. In most normal patients, the amount of fluid produced is equal to the amount of fluid drained. This equilibrium of aqueous humour fluid is what creates the “normal” pressure in the eye.
Primary Open Angle Glaucoma
The most common type of Glaucoma is called Primary Open Angle Glaucoma (POAG). With Primary Open Angle Glaucoma, patients have an elevated Intraocular Pressure (IOP) measurement that may result in damage to the optic nerve if left untreated. The higher than normal intraocular pressure usually occurs because the rate of drainage of fluid through the meshwork is insufficient. Unfortunately they eye continues to produce fluid and overfills the closed space of the anterior chamber of the eye resulting in the elevated pressure. It is this raised pressure (IOP) that can cause permanent changes and even damage to the optic nerve. The optic nerve is the critical communication pathway between the back of the eye and the brain and is responsible for transmitting signals and images. Once the optic nerve is damaged, it is not capable of regenerating, resulting in vision loss. Thus, it is important to monitor intraocular pressure regularly in order to detect and control elevated intraocular pressure as if left untreated, a high intraocular pressure (IOP) can, over time, lead to slow progressive, permanent damage to the optic nerve that can result in blindness.
Angle Closure Glaucoma
A much less common, but significant type of Glaucoma, is called Angle Closure Glaucoma. Angle Closure Glaucoma is characterized by closure or blockage of the drainage structure of the eye-the trabecular meshwork. The trabecular meshwork is really similar to a fine filter. If the filter becomes blocked by anything such as changes in the shape or structure of the trabecular meshwork, the pressure can rise significantly. If the filter becomes closed suddenly, it will cause an acute rise in the intraocular pressure (IOP). This can cause pain, redness, blurred vision and if left untreated permanent loss of vision. There are several different causes of Angle Closure Glaucoma but the most common is Acute Angle Closure Glaucoma due to anatomic variations of the structures within one's eye. This is much more common in far-sighted eyes and is most prevalent between ages of 45 and 60. If our Ophthalmologists/Optometrists detect a narrowed angle during your routine eye examination, they may perform a special examination called a gonioscopy to evaluate your risk for Angle Closure Glaucoma.
Acute Angle Closure Glaucoma is most effectively treated with a Laser in order to create a small hole in the peripheral iris tissue to redirect the aqueous fluid and prevent the trabecular meshwork from becoming blocked.
Glaucoma Risk Factors
There are a number of factors that may put patients at higher risk for developing Glaucoma. Some of these factors are more significant than others, and some are highly predictive.
Increased Intraocular Pressure-if you have been found to have an elevated intraocular pressure during a routine eye examination or Glaucoma screening, you are considered to be at greater risk for developing Glaucoma.
Age-the likelihood of developing Glaucoma tends to increase with age, and in particular when you are above 40-50.
Race -certain genetic factors seem to predispose African-Americans to a higher likelihood of developing Glaucoma.
Myopia-the nearsighted eye has anatomical features that can increase the risk of Glaucoma.
Hypertension-patients who are being treated for high blood pressure are at greater risk for Glaucoma.
Diabetes-as with hypertension, those being treated for diabetes are considered to be at greater risk for Glaucoma.
Family History-if others in your family have been diagnosed with Glaucoma, your risk of developing Glaucoma increases considerably. This is particularly true for siblings of Glaucoma patients, who according to the Nottingham Glaucoma Study, as previously referenced, have a 5-fold increase in risk for developing Glaucoma.
Treatment of Glaucoma
Fortunately today we have many excellent options for treating Glaucoma. For purposes of this discussion we will limit our treatments to those used for treating Primary Open Angle Glaucoma, as it is the most common type of Glaucoma.
Primary Open Angle Glaucoma is treated by three different approaches depending on the severity of the disease and the ability of each treatment option to adequately the disease progression.
Medical Treatment of Glaucoma
By far the most common form of treatment for Glaucoma is the use of eyedrops. In fact 80% of patients diagnosed with Glaucoma can be successfully treated with one or more of a large list of prescription medications. These medications work by either decreasing the amount of fluid being produced inside the eye or by increasing the rate of drainage of fluid from the eye. In the vast majority of cases, by using the eye drops as prescribed-1-2 times per day it is possible to effectively control the intraocular pressure and the progression of the disease. Some patients may experience side effects or have reactions to these eyedrops that make them a poor treatment option. Also, some patients just do not respond well to the eye drops and thus are unable to achieve adequate control with eye drops alone.
Laser Treatment of Glaucoma
For those patients who can not be successfully treated with eye drops, today there are a number of types of Lasers that can be used to help control the intraocular pressure (IOP). In fact, today laser treatment for Glaucoma is widely used to help those prevent vision loss and is becoming a Glaucoma treatment of choice for many patients who have problems with eye drops or are unable to instill them properly.
Argon Laser Trabeculoplasty (ALT) is a glaucoma laser treatment that helps to reduce the intraocular pressure by causing more effective drainage of fluid from the eye. It has been used successfully for many years. However, for some patients, the effect of ALT seems to diminish over time. This is troubling, as ALT cannot be repeated. Another type of laser treatment for Glaucoma is called Selective Laser Trabeculoplasty (SLT). This type of laser treatment is growing rapidly as a treatment method for Glaucoma because it seems to be a bit gentler on the eye, and more importantly, should the effect be diminished over time, SLT can be repeated several times in order to control the disease and prevent vision loss. SLT is becoming and important treatment option not only for Glaucoma patients who are unable to use eye drops or are not responsive to eye drops, but as a primary treatment method to possible help Glaucoma patients avoid the need for eye drops altogether.
Surgical Treatment of Glaucoma
Finally, in the event that patients are unable to achieve satisfactory results with either eye drops or laser treatment for Glaucoma, there are surgical procedures that Our Ophthalmologists may perform in order to help reduce and stabilize the intraocular pressure (IOP) and prevent vision loss. These include procedures such as trabeculoplasty whereby the trabecular meshwork is dissected in order to help fluid drain more effectively from the eye.
As you can see, Glaucoma is a complex eye disease, but is successfully treated when found early in its course. The Cheshire Consulting Centre and it’s staff, under the medical direction of oure experts provide the full scope of diagnostic testing and treatment options as well as the patient education necessary in order to get the best possible outcomes for their patients. If you or a family member or friend have not had a recent screening and examination for Glaucoma, please take a moment to request an appointment so that you can be sure your eyes are healthy.
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Glaucoma
