Introduction to glaucoma
Open-angle glaucoma is the most common form of glaucoma. Ninety percent of glaucoma patients have open-angle glaucoma. It is estimated that over two million Americans have some type of glaucoma and half of them are not aware they have the disease. Although it cannot be cured, it can usually be controlled with treatment.
The eye receives its nourishment from a clear fluid that circulates inside the eye. This fluid must be constantly returned to the bloodstream through the eye’s natural drainage system called the trabecular meshwork. If the fluid is not able to drain properly through trabecular meshwork pressure begins to build within the eye. The pressure pushes against the delicate optic nerve that connects the eye to the brain. If excessive pressure continues over an extended period, permanent vision loss can occur.
In the early stages, there can be no symptoms, pain, or visible indications of the disease. Some patients might feel a slight aching in the eyes. As the disease progresses, patients experience a gradual loss of peripheral vision and may see halos around lights. Vision in lo light levels becomes more and more difficult even with corrective eyewear.
Although glaucoma can occur in people of all races and at any age, the risk of developing glaucoma increases if you are: African American; a relative of someone with glaucoma; diabetic; or very nearsighted.
Those considered to be at higher risk, including those over the age of 60 should have their pressure checked every year or two. Everyone should be checked for glaucoma at around age 35 and again at age 40.
Types of Testing
A tonometer (above) is used to check eye pressure. After applying numbing drops, the tonometer is gently pressed against the eye and its resistance is measured and recorded.
An ophthalmoscope (above) may be used to examine the shape and color of your optic nerve. The ophthalmoscope magnifies and lights up the inside of the eye. If the optic nerve is not a healthy pink color or appears to be cupped, the additional tests will be performed.
A perimetry (above) test maps the field of vision to see any pattern of changes that may indicate the early stages of glaucoma. Looking straight ahead into a white, bowl-shaped area, you’ll indicate when you’re able to detect lights as they are brought into your field of vision.
Gonioscopy (above) is used to check if the angle where the iris meets the cornea is open or closed. This helps your doctor diagnose which type of glaucoma is present – open-angle glaucoma or narrow-angle (closed) glaucoma.
The doctors at Slade and Baker Vision Center will use one of three basic types of treatment for glaucoma to lower the pressure in the eye: medicines, laser surgery, or filtration surgery.
Medicines work by slowing the production of fluid inside the eye or by improving the flow of fluid through the drainage meshwork. These medicines come in pill and eye drop form and typically must be taken between one to four times per day to be effective. Some of these medications have undesirable side effects, so we will work with you to determine which medication controls your pressure with the least amount of side effects. Medicine regimens should not be stopped without talking to us first, and you should notify all of your other physicians about the glaucoma medications you are taking.
For patients with narrow angle glaucoma or angle closure glaucoma, the anatomy of the front of the eye results in closure of the natural drain, causing high pressure and often pain. Laser peripheral iridotomy (LPI) can help add a “pressure release valve” to significantly reduce this risk. In many patients with narrow angles, performing cataract surgery or lens replacement surgery may be a permanent solution. This is because the new intraocular lens is narrower than the natural human lens, allowing the drainage angle to be more open and less likely to close.
Argon Laser Trabeculoplasty (ALT) & Selective Laser Trabeculoplasty (SLT)
Argon Laser Trabeculoplasty and Selective Laser Trabeculoplasty surgery treat the drainage canal. Both procedures require only numbing eye drops. The laser beam is applied to the trabecular meshwork, opening the drainage canals and improving the rate of drainage. ALT & SLT laser surgery often reduces the need for daily medications.
Endoscopic Cyclophotocoagulation (ECP)
Endoscopic Cyclophotocoagulation (ECP) is another laser procedure used to treat glaucoma. This procedure treats the ciliary body to reduce the amount of fluid production thereby reducing the intraocular pressure. ECP is most often performed along with cataract surgery but can be done on an outpatient basis when in the best interest of the patient. In most cases, ECP will reduce or eliminate a patients’ need to take glaucoma medications.
Filtration surgery is performed when other methods of treatment prove unsuccessful in controlling eye pressure. Filtration surgery creates an alternate drainage channel for fluid to drain from the eye.
Drs. Slade and Walton use the iStent to help aqueous fluid drain back into collector channels to lower eye pressure.
The smallest human implant, the iStent is typically placed by Dr. Slade or Dr. Walton in conjunction with cataract surgery. Once in the eye, it is only visible with a microscope.