What is Glaucoma?

Sometimes called the silent thief of sight, glaucoma can damage your vision so gradually you may not notice any loss of vision until the disease is at an advanced stage.

Glaucoma is a multi-factorial, complex eye disease with specific findings such as optic nerve damage and visual field loss. While increased pressure inside the eye (called intraocular pressure or IOP) can be present, patients with normal range IOP can develop glaucoma.

There is no specific level of elevated eye pressure that definitely leads to glaucoma. On the other hand, there is no lower level of IOP that will absolutely eliminate a person’s risk of developing glaucoma. In summary, if glaucoma can develop with any IOP level, then there really is no “normal” intraocular pressure. 

Early diagnosis and treatment of glaucoma is the key to preventing vision loss. 

 Are there Different Types of Glaucoma?

There are two main types of glaucoma:

Open-Angle Glaucoma

Also called wide-angle glaucoma, this is the most common type of glaucoma. The drainage structures of the eye appear open, but fluid in the eye does not flow properly through the drain system (resistance shown to be at the level of the trabecular meshwork in most cases). The eye pressure can be high or “normal”. Normal-tension or low-tension glaucoma is a type of open-angle glaucoma. Open-angle glaucoma can also be divided into

• primary open-angle glaucoma. No additional abnormal findings seen on exam.
• secondary open-angle glaucoma. Seconary open-angle glaucoma includes pseudoexfoliation and pigmentary glaucoma.

Angle-Closure Glaucoma

Also called acute or chronic angle-closure or narrow-angle glaucoma, this type of glaucoma is less common, but can cause a sudden buildup of pressure in the eye which could cause rapid loss of vision.

Drainage may be poor because the angle between the iris and the cornea (where a drainage channel for the eye is located) is too narrow. The pupil opens too wide or the lens is too thick (as a cataract is forming), narrowing the angle and blocking the flow of the fluid through that channel.

 Who should be checked for Glaucoma?

It is important to have your eyes examined regularly. Your eyes should be tested:

• before age 40, every two to four years
• from age 40 to age 54, every one to three years
• from age 55 to 64, every one to two years
• after age 65, every six to 12 months

The number of times your eyes need to be checked is ultimately based on your specific findings. This can only be determined after your eyes have been examined. Those with high risk factors should be tested every 1-2 years after age 35.

The following are groups at higher risk for developing glaucoma:

African-Americans

Glaucoma is the leading cause of blindness among African Americans. It is 6-8 times more common in African-Americans than in Caucasians.

People Over Age 60

Glaucoma is more common among older people. You are 6 times more likely to develop glaucoma if you are over 60 years old.

Family History of Glaucoma

The most common type of glaucoma, primary open-angle glaucoma, is inherited. If members of your immediate family (father, mother, brothers, or sisters) have glaucoma, you are at a much higher risk of developing glaucoma than the general population.

Family history increases risk of glaucoma 4-9 times.

Hispanics (Especially Older Age Groups)

Risk for Hispanic populations in the United States is greater than those of predominantly European ancestry, and that the risk can equal that of African-Americans after age 60.

Asians

Asians appear to be at increased risk for angle-closure glaucoma. Angle-closure glaucoma accounts for less than 10% of all diagnosed cases of glaucoma. Low-tension glaucoma is seen at higher rates in Japan.

Corticosteroid Users

• A 1997 study reported in the Journal of American Medical Association demonstrated a 40% increase in the incidence of ocular hypertension and open-angle glaucoma in adults who required a steroid inhaler to control asthma.
• Steroid injections into joints or oral steroids can also increase intraocular pressure.
• If you use over-the-counter flonase (fluticasone) nasal spray, this is a corticosteroid and may increase your eye pressure, thereby putting you at increased risk of developing glaucoma. 

History of Eye Trauma

Injury to the eye may cause secondary open-angle glaucoma. This type of glaucoma can occur immediately after the injury or many years later. Blunt trauma or injuries that penetrate the eye can damage the eye’s drainage system, leading to traumatic glaucoma. The most common cause is sports-related injuries (baseball and boxing are considered high risk sports).

Other Risk Factors

Other possible risk factors include:

• High myopia (nearsightedness)
• Hypertension
• Central corneal thickness less than 0.5 mm

How is Glaucoma Detected?

 At the San Antonio Eye & Face Institute, we have all of the commonly used diagnostic tools for glaucoma detection at our disposal. We use a combination of some or all of these diagnostic tests to diagnose and monitor patients with glaucoma.

• Tonometry – measurement of the intraocular pressure using anesthetic drops and a tonometer
• Ophthalmoscopy – detailed examination of the optic nerve under magnification 
• Perimetry – a complete mapping of the peripheral vision using specialized software
• Gonioscopy – examination of the drainage angle of the eye using a mirrored examination lens 
• Pachymetry – measurement of the thickness of the central cornea 
• Nerve Fiber Layer Analysis – measures defects in the nerve fiber layer (sometimes detects glaucoma earlier)
• Pattern Electroretinography (pERG) – measures the electrical activity of the retina (can be use to detect early glaucoma)

Testing for glaucoma will be scheduled after your initial eye examination. It can take up to one hour, so it will not be performed at your initial visit. Documentation of your optic nerve appearance will be obtained with standard color photographs using a special camera. 

If you have been diagnosed with glaucoma, testing will be performed periodically to monitor for stability/progression. We typically perform testing  in the afternoon on some Tuesdays and on Friday mornings. Your testing sessions will be scheduled as a separate appointment from your clinic visits 

What is the Goal of Glaucoma Treatment?

Glaucoma is treated in one of 3 ways. The first method is to use eye drops that reduce the intraocular pressure. If eye drops are reducing the eye pressure or if the patient is having unacceptable side effects from drops or has difficulty complying with daily use, then selective laser trabeculoplasty (SLT) may be recommended.

For patients where drops and/or SLT have not reduced the IOP sufficiently, other laser treatments like micro-pulse diode cyclophotocoagulation may be considered. In some cases, incisional surgery may be required to reduce the intraocular pressure.

At this point in time, the only thing that appears to stop the progression of glaucoma is intraocular pressure reduction. That is why every treatment for glaucoma is focused on pressure reduction.

3 Methods to Reduce Pressure in Glaucoma?

Eye Drops for Glaucoma

These either reduce the formation of fluid in the front of the eye or increase its outflow. Side effects of glaucoma drops may include allergy, redness of the eyes, brief stinging, blurred vision, and irritated eyes. Some glaucoma drugs may have systemic side effects. Be sure to tell your doctor about any glaucoma medication you are currently taking or are allergic to.