Glaucoma Risk Factors, Types, Diagnosis & Treatment at The Eye Clinic of texas serving greater Houston in Galveston, Texas City & League City.

By Bernard Milstein, M.D.

The eye doctors at The Eye Clinic of Texas provide examination, diagnosis and treatment of glaucoma for patients from throughout greater Houston and Galveston. Glaucoma is a term that is used to describe a broad range of eye problems that can damage the optic nerve and cause loss of vision. The pressure inside the eye, called Intraocular Pressure (IOP), generally falls within a range that is considered “normal”. Many patients believe that glaucoma is simply due to a high pressure within the eye. While a high intraocular pressure can be one cause of glaucoma, and in fact is the most common cause of glaucoma, a high IOP may not be the only cause of glaucoma. There are a number of possible causes of glaucoma. Regardless of the cause, the various types of glaucoma share a common factor-if not diagnosed early, treated properly and controlled, it will result in permanent vision loss and potentially blindness. 

Glaucoma is one of the leading causes of blindness for patients between the ages of 18-65 years of age. It is estimated that approximately 3 million people have Glaucoma, yet only half of these actually know that they have it. In the United States alone, there are approximately 100,000 patients who are believed to be legally blind from glaucoma.

Most serious eye problems usually produce some symptoms that make patients uncomfortable or disturb their vision. Unfortunately,  the  most common type of glaucoma can begin without any symptoms or obvious loss of vision. It is insidious in onset and, if not diagnosed and treated early in its course will lead to progressive, permanent, and unnoticed vision loss. This is why it is essential to diagnose and treat glaucoma as early in its course as possible through regular eye examinations. Fortunately, with early detection and diagnosis, in the vast majority of cases, glaucoma can be treated and controlled so that vision loss can be prevented.

Glaucoma Risk Factors
Everyone is at risk for glaucoma. However, depending on your general health, eye health and other family history considerations, there are a number of factors that that may influence your likelihood of developing glaucoma. These “Glaucoma Risk Factors” are important to understand in assessing your own personal risk for developing Glaucoma. Glaucoma risk factors include the following:

High Intraocular Pressure
A key warning sign of glaucoma is having a higher than normal Intraocular Pressure (IOP). Anyone with an elevated Intraocular Pressure (IOP) is considered to be at risk for developing glaucoma.

Age
There is a direct relationship between age and the likelihood of developing glaucoma. The chances of developing glaucoma increase considerably after the age of 40. In fact you are six times more likely to get glaucoma if you are over 60 years of age-even if you have no other family or medical history that is significant-and your risk is greater if you have any family history of glaucoma or other systemic or eye disease that compromises your circulation such as diabetes.

Race
Race plays a significant role in the likelihood of developing glaucoma. African-Americans have certain genetic factors that cause a higher likelihood of developing glaucoma. In fact they have a six to eight fold increased risk for glaucoma. Glaucoma is the leading cause of blindness in African-Americans. Asians appear to have higher risk for developing Narrow Angle Glaucoma. In addition, Hispanics over the age of 60 seem to be at increased risk as well.

Myopia
Certain patients who are severely nearsighted have a higher risk of developing glaucoma. This is believed to be due to extremely nearsighted eyes having anatomical features that can increase their risk of glaucoma.

Hypertension or High Blood Pressure
It is absolutely critical that patients who have hypertension or high blood pressure take their prescribed medication on a consistent basis. Hypertension has been variably found to be a risk factor for the development of glaucoma. Paradoxically, patients who take medication for high blood pressure may be at greater risk for glaucoma as a result of the medication lowering the blood pressure and thus decreasing circulation within the optic nerve.

Diabetes
Diabetes can cause general problems with circulation throughout the body-including the eye. As a result of the poor circulation, patients with diabetes are considered to be at greater risk for developing glaucoma due to these general circulation problems.

Family History
Any family history of glaucoma is considered a very significant risk factor. If any members of your family have been diagnosed with glaucoma, it increases the likelihood that you will develop glaucoma by 4-9 times over the general population. This is particularly true for siblings of glaucoma patients who have a 5-fold increase in risk for developing glaucoma.

Other Glaucoma Risk Factors
In addition to these factors, if you have had trauma to your eyes (i.e. a sports injury or car accident) or if you have been treated for Asthma for long periods of time with steroid inhalers or have a corneal thickness less than 0.5mm, you too may have an increased risk for glaucoma.

Types of Glaucoma
There are many types of Glaucoma. However, there are two main types of Glaucoma: Primary Open Angle Glaucoma (POAG), and Angle Closure Glaucoma. Sometimes it is possible to have damage to the optic nerve, even with a “normal” Intraocular Pressure (IOP). When optic nerve damage has occurred despite a normal IOP, this is called Normal Tension Glaucoma. Secondary Glaucoma refers to any case in which another disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss. We will limit our discussion to Primary Open Angle Glaucoma and Angle Closure Glaucoma.

Primary Open Angle Glaucoma
The most common type of glaucoma is Primary Open Angle Glaucoma (POAG). In the “normal” eye, there is a continuous production and drainage of a clear colorless fluid called “Aqueous Humor”. This production and drainage is balanced so that an equal amount is produced and drained in order to maintain an equilibrium resulting in a “normal’ Intraocular Pressure (IOP). Patients with Primary Open Angle Glaucoma usually have an increase in Intraocular Pressure (IOP) upon routine measurement, called Tonometry.

Primary Open Angle Glaucoma illustration

Primary Open Angle Glaucoma is secondary to a decrease in the ability of the eye to drain the aqueous fluid. Any elevation of Intraocular Pressure (IOP) is considered “abnormal. This elevation in pressure (IOP) causes the circulation in the optic nerve to become compromised, depriving it of oxygen and nutrients, resulting in permanent changes and even damage to the optic nerve. Any damage to the optic nerve can result in a loss of vision. The optic nerve is the connection responsible for communicating visual images between the retina and the brain. When the optic nerve is damaged, it is not able to carry visual images, resulting in vision loss. This is why it is so important to monitor, detect and control Intraocular Pressure (IOP). If left untreated, an elevated Intraocular Pressure (IOP) may, over time, cause slow, progressive and permanent damage to the optic nerve that can result in blindness. This is the nature of Primary Open Angle Glaucoma.

Angle Closure Glaucoma
Angle Closure Angle Closure Glaucoma can be divided in two main types: Primary Angle Closure Glaucoma and Acute Angle Closure Glaucoma. Although Angle Closure Glaucoma occurs much less frequently than Open Angle Glaucoma, it is important to understand it because it has the ability to produce considerable vision loss in a short period of time.

Primary Angle Closure Glaucoma accounts for approximately 10% of all cases of glaucoma and about 2/3 of these once again produce no symptoms for patients.

Acute Angle Closure Glaucoma is one of the only types of glaucoma that produce distinct symptoms that include pain, light sensitivity, redness, blurred vision, colored haloes around lights and nausea or vomiting.

Angle Closure Glaucoma is characterized by a blockage or complete closure of the drainage structure of the eye called the Trabecular Meshwork. The Trabecular Meshwork is actually a fine filter. If it is blocked or obstructed by any alteration in the size or shape of the surrounding structures, or by change in the size or shape of the tissue itself, it will cause the Intraocular Pressure to elevate. In instances where the meshwork becomes blocked abruptly, it will cause a sudden rise in the Intraocular Pressure (IOP), resulting in Acute Angle Closure Glaucoma. Acute Angle Closure Glaucoma is characterized by this sudden rise in pressure which will can cause pain, redness, light sensitivity, colored haloes around lights, nausea or vomiting and blurred vision, and if left untreated permanent loss of vision.

Acute Angle Closure Glaucoma is considered a medical emergency. If you experience a sudden onset of pain, redness, blurred vision, light sensitivity, haloes around lights, nausea and vomiting, please call The  Eye Clinic of Texas at 800-423-3937 and relay these symptoms to the receptionist so that you can be given an appointment immediately.

While there can be a several causes of Angle Closure Glaucoma, it is most often caused by anatomical changes within the internal structures of the eye. Angle Closure Glaucoma is considerably more common in farsighted eyes, which tend to be smaller and in patients between the ages of 45-60 years of age where the Crystalline Lens is beginning to enlarge.

During your routine eye exam if one of The  Eye Clinic of Texas doctors observes or measures a narrowed angle, he or she will perform an additional examination procedure called Gonioscopy. This will allow the doctor to directly examine the Trabecular Meshwork and the angle in order to carefully assess your predisposition to Angle Closure Glaucoma. By placing a special contact lens on your eye and then using the slit lamp biomicroscope to fully examine the meshwork and the angle with Gonioscopy the doctor will be able to make a thorough evaluation.

In the event that you are at risk for Angle Closure Glaucoma or in the event that you have Acute Angle Closure Glaucoma your eye doctor may initially prescribe some medication to begin to lower the pressure. Also, he or she will most likely recommend performing a type of Glaucoma Laser procedure in order to produce a small opening or hole in the Iris so that Aqueous Humor can drain from the eye more effectively. This procedure, called a “Laser Iridotomy”, is quite successful in treating Angle Closure Glaucoma and preventing recurrences.

Diagnosis & Testing of Glaucoma
The best way to maintain eye health and preserve your vision is to have regular and complete eye examinations with the appropriate level of diagnostic testing for Glaucoma as recommended by the eye doctors at The Eye Clinic of Texas. During your examination, our eye doctors and staff may perform a number of tests in order to make the most accurate diagnosis of glaucoma. These include the following testing procedures:

Tonometry
The Tonometry Test is a method of measuring your Intraocular Pressure (IOP). This test involves first placing some eye drops into your eyes to numb them and then lightly touching the surface of the cornea with a specialized measuring instrument. There is no discomfort involved. The test is quick and gives the eye doctors the first piece of important information in determining whether you have glaucoma.

Ophthalmoscopy
Ophthalmoscopy is a method of carefully examining the inside of the eye-especially the optic nerve-in order to detect Glaucoma. Some eye drops will be placed in your eyes in order to dilate your pupils so that the doctors can make a clear and direct observation of the optic nerve. The examination will take place in a darkened room using different types of Ophthalmoscopes in order to examine the shape and color of your optic nerve.

If either the Intraocular Pressure (IOP) is elevated or the optic nerve appears unusual, additional tests will be necessary in order to complete the glaucoma examination. These may include the following test procedures:

Visual Field Perimetry

Perimetry or Visual Field testing is an important part of the glaucoma examination. During this test you will be asked to sit in front of a large “bowl like” instrument and look directly straight ahead. A computer program will present a number of lights in different positions of their “side” or peripheral vision to see how sensitive your side vision is in various directions. The computer will then plot an actual map of the field of vision so that your doctor can interpret this map in conjunction with other examination tests in order to understand how well the optic nerve is functioning. Glaucoma usually affects your side vision before your central vision, so visual field testing can often show any problems from glaucoma before you can notice them.

Gonioscopy
Gonioscopy is a quick and painless test that allows the doctors to directly observe the health and condition of the angle where the Iris meets the Cornea. By directly observing the angle and its status your eye doctor will be know more about whether you are at risk for the angle to become closed or whether the Trabecular Meshwork appears to have a normal anatomical structure.

Optic Nerve Computer Imaging
At The Eye Clinic of Texas we use the most advanced computer imaging technology in order to make the earliest and most accurate diagnosis of Glaucoma. Our eye doctors use OCT or Ocular Coherence Tomography to precisely evaluate the health of your Optic Nerve. The OCT uses a method called “optical coherence tomography” that is capable of creating digital images through the use of special beams of light in order to create a contour map of the optic nerve and measure the retinal nerve fiber thickness. In many regards this is similar to the CT Scans used to study organ systems and tissues throughout your body. 

The goal of OCT Optic Nerve Computer Imaging is to give our eye doctors the ability to detect the slightest loss of optic nerve fibers, at the first possible moment, in order to diagnose glaucoma at the earliest possible stage in order to stop the progression of the disease and preserve your vision. These tests are also useful in monitoring for the possibility of progression by comparing tests over time. We perform OCT Optic Nerve Computer Imaging right in the comfort and convenience of our office at The  Eye Clinic of Texas

Pachymetry Measurement of Corneal Thickness
The National Eye Institute of the National Institutes of Health released a key study called the Ocular Hypertension Study (OHTS). In this study an important finding was made regarding corneal thickness and its role in Intraocular Pressure and the development of Glaucoma. The OHTS study found that corneal thickness is important because it can alter the accuracy of the measurement of Intraocular Pressure, potentially causing doctors to treat you for a condition that may not actually exist or to treat you unnecessarily when you are normal. Your actual Intraocular Pressure may be UNDERESTIMATED if you have thin corneas and it may be OVERESTIMATED if you have thicker corneas. In addition, it appears that patients with thin corneas may be inherently more likely to develop glaucoma apart from its influence on the measurement of intraocular pressure.

During a glaucoma examination, your doctor or a staff member may perform a Pachymetry Test to measure your corneal thickness as part of your examination and consider this finding in conjunction with the other glaucoma testing in order to make the most accurate diagnosis. The Pachymetry Test is a simple, quick and painless way of accurately measuring your corneal thickness that we do right in our office. The test is performed by first placing some drops in your eyes to make them numb and then lightly touching the cornea with a “pencil like” probe that uses sound waves to precisely measure your corneal thickness.

Treatment of Glaucoma

There are three main methods that your eye doctor at The Eye Clinic of Texas may recommend to treat Glaucoma: Medical Treatment of Glaucoma, Laser Treatment of Glaucoma and Surgical Treatment of Glaucoma.

These treatment options for controlling Glaucoma are quite important, as glaucoma has no cure. The good news is that in almost all cases, Glaucoma is treatable, but must be diagnosed as early as possible. Thanks to advances in the Medical Treatment of Glaucoma, Laser Treatment of Glaucoma and Surgical treatment for Glaucoma, The Eye Clinic of Texas doctors will be able to recommend an individual treatment plan that is best for each patient. The following information is limited to treatment of Primary Open Angle Glaucoma, as it is the most common type of Glaucoma.

Medical Treatment of Glaucoma
Primary Open Angle Glaucoma is most often treated with eye drops. There are many types of eye drops that can be prescribed to lower Intraocular Pressure (IOP). By using a single type of medication or sometimes 2 eye drops in combination, more than 80% of the patients with Open Angle Glaucoma can be successfully treated. These eye drops work by either decreasing the amount of fluid being produced inside your eye or by increasing the rate of drainage of fluid from your eye. For most patients, by using the eye drops as prescribed-1-2 times per day it is possible to control the Intraocular Pressure (IOP) and slow or even halt the loss of vision.

Unfortunately, some patients are unable to achieve adequate control with eye drops alone, or may experience intolerable side effects from the eye drops, and require Laser Treatment for Glaucoma in order to maintain control.

Laser Treatment of Glaucoma
Our eye physicians and surgeons have found that the use of Laser Treatment for Glaucoma has become an important treatment option for many patients. In the past, Laser Eye Surgery for Glaucoma was considered a “last resort” before Glaucoma Surgery. Today, thanks to advances in lasers, using a laser treatment for Glaucoma in conjunction with the eye drop treatment or sometimes even using the Laser Treatment as the primary treatment, are excellent options to help maintain control and slow or stop the progression of the disease. Laser Treatment for Glaucoma is regularly used to help prevent vision loss and is becoming a Glaucoma treatment of choice for many patients who have problems with eye drops or are unable to use eye drops properly.

Surgical Treatment of Glaucoma
For a small number of patients, even with the maximum medical therapy with Glaucoma eye drops and Laser Eye Surgery, it is still not possible to achieve good stable control of their disease and stop the progression of vision loss.

Surgical Treatment of Glaucoma illustration

For these patients a number of surgical procedures can be performed to help achieve control of the Intraocular Pressure (IOP) and help to slow or stop the progression of the disease. These include removing a tiny piece of the Trabecular Meshwork, a surgical procedure called “Trabeculectomy”, “Sclerostomy” or “Filtering Procedure”, or even implanting a microscopic Glaucoma Valve or Stent to help reduce and stabilize the Intraocular Pressure (IOP) and prevent vision loss.

The best way to prevent vision loss from glaucoma is through early detection, diagnosis and treatment. If you or someone you know is at risk for glaucoma or needs a glaucoma eye exam please call The Eye Clinic of Texas at 800-423-3937.