- We strive to provide complete care for our patients. Learn more about all the services we provide.
There are different types of Glaucoma, all of which results in vision loss due to optic nerve damage. Glaucoma is one of the leading causes of blindness in the US and is usually asymptomatic in the early stages during which significant nerve damage occurs. The two main Glaucoma sub groups are Primary Open Angle Glaucoma and Narrow Angle Glaucoma.
Primary Open Angle Glaucoma (POAG) constitutes the vast majority of diagnosed glaucoma cases worldwide.
The eye is always producing aqueous humor, a clear fluid that then drains out of the anterior chamber through the Trabecular Meshwork. This aqueous fluid is constantly being produced and drained, creating a delicate balance in eye pressure. Glaucoma occurs when the eye produces too much fluid or the drainage system is faulty, resulting in a rise in eye pressure. The precise mechanism for why this happens is still unknown, however, the increased pressure causes damage to the Optic Nerve’s blood supply, therefore, depriving the nerve of necessary oxygen and nutrients.
Keep in mind that one-third of all open angle glaucoma patients present with normal eye pressure, which is why all the diagnostic tools that we are about to discuss are necessary for an accurate diagnosis.
Early vision loss due to glaucoma occurs in the periphery with no symptoms to the patient. Once damage occurs to the nerve cells, restoration of vision is minimal even with good treatment, making early detection and then control of the disease extremely important.
The photo: Advanced defects are evident in this picture of primary open angle glaucoma.
How can open-angle glaucoma be treated?
Open-angle glaucoma cannot be cured but it can usually be controlled. The most common treatments are:
The five most common drops for reducing intraocular pressure (IOP) are Beta blockers, Prostaglandin analogs, Beta blocker/Prostaglandin analog combinations, Carbonic Anhydrase inhibitors and Alpha agonists. Each medication has a specific dosing schedule and strict adherence to instructions for maximum control is important. It is often necessary for more than one medication to be prescribed to keep the IOP under control.
These may be prescribed in conjunction with eye drops or laser treatments.
Laser surgery may be recommended (with and without eye drops) to control IOP. Selective Laser Trabeculoplasty (SLT) and Argon Laser Trabeculoplasty (ALT) facilitate fluid outflow by creating openings in the Trabecular Meshwork, where fluid drains from the anterior chamber.
Trabeculectomy, or filtration surgery is usually reserved for patients whose pressure cannot be controlled with the above more conservative measures or when optic nerve damage is extensive.
Who is most likely to get open angle glaucoma?
Studies show that African Americans are 5 times more likely to develop glaucoma than Caucasians and although anyone can get glaucoma, the following are at higher risk:
- People age 60 or older
- African Americans over the age of 40
- Family history of glaucoma
- Taking certain medications, like Steroids
- People with Sleep Apnea
What are the symptoms of glaucoma?
Open Angle Glaucoma has no symptoms until significant damage has been done to the optic nerve. If left untreated, loss of peripheral vision may be noticed and as the disease worsens, the field of vision narrows and total blindness can result. Routine eye exams are the key for the early detecting and controlling of glaucoma.
How is glaucoma detected?
Although increased eye pressure is an important factor it alone does not confirm a diagnosis of glaucoma. Of equal importance are the appearance of the optic nerve head (ONH), the thickness of the cornea, peripheral visual fields and the thickness of the retinal nerve fiber layer. The optic nerve is best evaluated through a dilated pupil and by digital retinal imaging. Patients often ask why annual dilation is necessary and this evaluation of the optic nerve is just one of the many good reasons.
If there is any suspicion of glaucoma based on increased eye pressure or unusual optic nerve appearance, additional testing will be recommended.
In summary, it is important to follow the recall schedule that Dr. Stokol recommends for eye examinations. Remember that simply checking the pressure in the eye does not rule out the presence of glaucoma.
Narrow-Angle Glaucoma (NAG):
In this type of glaucoma, there is an anatomical narrowing of the drainage angle of the eye, which limits fluid from leaving the eye. An anatomically narrow-angle that closes causes sharply elevated intraocular pressure. This is usually accompanied by significant eye and head pain as well as cloudy vision. This rise in eye pressure can damage the optic nerve in a very short period of time.
How is narrow-angle glaucoma treated?
Once the potential for narrow-angle glaucoma is diagnosed by a simple test called Gonioscopy, a preventative procedure called Laser Peripheral Iridectomy (LPI) can be performed, which facilitates flow within the eye.
For Information on these and other diseases of the eyes, visit www.nei.nih.gov