Glaucoma is a class of eye diseases associated with progressive loss of a patient’s field of vision related to injury to the optic nerve. Classically, glaucoma is correlated with the pressure within the eye. There are different types of glaucoma, which are classified by the mechanism causing the pressure in the eye to rise. The primary classes of glaucoma are divided into closed (or narrow) angle glaucoma and open angle glaucoma.
HOW GLAUCOMA AFFECTS VISION
HOW DOES THE PRESSURE IN THE EYE RISE?
The eyeball is a closed system which makes its own fluid, called aqueous, to supply nutrients to its internal structures. In order for the eye to maintain a healthy pressure, it must also remove fluid or the pressure rises. If the pressure gets too high, the fibers which make up the optic nerve begin to die, thereby preventing the “picture” which is formed on the retina from reaching the brain – where we actually “see” an object. Your surgeon would classify narrow angle or open angle glaucoma on whether the area that drains the fluid is obstructed hence, “closed” or not “open”. The open angle glaucoma is vastly more common than closed angle glaucoma.
Normally, there is an inflow and outflow of fluid within the eye (green arrows). Note the normal appearance of the optic nerve in the back of the eye. Place your cursor over the image and observe the cause and effect of glaucoma. When the fluid outflow becomes blocked (red arrows), pressure builds up (blue arrows) in the eye. This increased pressure can damage the optic nerve and result in reducing vision.
TYPES OF GLAUCOMA
CLOSED ANGLE GLAUCOMA
This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much more rare and is very different from open angle glaucoma in that the eye pressure usually rises very quickly.
This happens when the drainage canals get blocked or covered over, like a sink with something covering the drain.
With angle closure glaucoma, the iris is not as wide and open as it should be. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room.
A simple test can be used to see if your angle is normal and wide or abnormal and narrow. Treatment of angle closure glaucoma usually involves surgery to remove a small portion of the outer edge of the iris. This helps unblock the drainage canals so that the extra fluid can drain. Usually surgery is successful and long lasting. However, you should still receive regular check-ups.
Symptoms of angle closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
OPEN ANGLE GLAUCOMA
Open angle glaucoma means that there is an elevated rise in the patient’s eye pressure without any apparent obstruction to the drainage area In essence, the part of the patient’s eye that drains the internal fluid, called the trabecular meshwork (TM), does not seem to be functioning properly. Because there is no obvious blockage to the TM, your surgeon tries to decrease pressure by either decreasing the amount of fluid the eye makes, or by artificially stimulating the TM to drain more fluid. In the United States, the most common initial measure to alter the internal production and/or drainage of aqueous is through the use of antiglaucoma medications. These medications are applied directly to the ocular surface in the form of drops. When medications fail to produce a desirable level of eye pressure control, the next level of treatment is typically a laser treatment called a trabeculoplasty. Laser trabeculoplasty is an office-based procedure where light energy is delivered to the drainage area of the eye and stimulates the TM to drain more fluid. Usually, the procedure takes 4-6 weeks for the patient to experience a lowering of the eye pressure.
When all other treatment measures fail, the next step is surgical control of intraocular pressure. The reasoning is, if medical and laser therapy are not capable of stimulating the TM to drain enough aqueous to keep the eye pressure low, then a new route of egress for the fluid needs to be made in order to lower the patient’s eye pressure to an appropriate level. The most common form of glaucoma surgery is called trabeculectomy. In a trabeculectomy, a microscopic canal is made through the wall of the eye to permit the aqueous to leave the eye with low resistance. The procedure is performed under a local anesthetic, on an outpatient basis.
DIAGNOSIS AND TREATMENTS
The key to preventing vision loss is early glaucoma detection. And, since your surgeon acquired the Heidelberg Retinal Tomograph II (HRT II), it has never been easier to be diagnosed for this blinding disease – often before vision suffers.
The HRT II is a confocal scanning laser ophthalmoscope. It not only detects the very early stages of glaucoma, it also provides eye doctors with essential information for monitoring the disease in follow-up exams. By scanning the optic nerve and adjacent nerve fiber layer, the HRT II produces a three dimensional topographic map. It generates extremely accurate, detailed data and comprehensive analysis that simply is not possible to obtain with traditional examinations.
The HRT II exam is fast, safe, and usually does not require dilating the eye. While a patient sits comfortably in a stationary position, a laser scans the eye for just a few seconds (at a lower energy level than that prodcued from a television remote control).
Glaucoma can develop in anyone. However, some people are considered at higher risk than others – including individuals over age 60, African-Americans over age 40, and people with high blood
pressure, diabetes, or a family history of glaucoma.
Pioneer Valley Ophthalmic Consultants in one of the few practices in the area to offer the comprehensive, non-invasive HRT II exam for early diagnostic monitoring of glaucoma. If you, or someone you know, is at high risk for glaucoma, contact the office today.
SLT (Selective Laser Trabeculoplasty) is a safe and simple 5 minute in-office laser treatment that effectively reduces the pressure in the eye for most patients with glaucoma. Its’ use has allowed for an improved quality of life for thousands of patients around the world. SLT patients do not need to take medications or at least as many medications. Studies have shown that less than 50% of glaucoma patients actually take their medications as prescribed and many stop taking them due to the numerous side effects experienced, cost, busy lifestyle and all other daily variables and challenges we all experience. Compliance is now controlled by your physician. The low percentage of non-responders to SLT therapy can simply begin traditional medications.
The benefits of SLT Therapy are:
- Improve your quality of life
- Eliminate or reduce your immediate need for medications
- Allows the eye to naturally heal itself
- Can be repeated if necessary
- No systemic side effects
If SLT cannot assist in lowering your intraocular pressure, you are still available to all other traditional treatment options.
Due to the nondestructive nature of SLT Therapy unlike traditional laser therapy, SLT can be used for the following conditions:
- Primary Open Angle Glaucoma
- Ocuar Hyper Tension
- Normal Tension Glaucoma
- Juvenile Glaucoma
- Aphakic Glaucoma
- Pigmentary Glaucoma
SLT Therapy is a treatment option for most glaucoma patients. As well most patients prefer to be treated with SLT-Therapy as a first treatment choice when first diagnosed with glaucoma.