Glaucoma
Glaucoma includes a group of conditions that cause damage to the optic nerve. These can often develop over many years without causing pain – so you may not experience vision loss until the disease has progressed. Glaucoma cannot be prevented, and vision lost to it cannot be restored. Left untreated, glaucoma can cause blindness. For these reasons, regular eye exams and early detection are critical.
The high eye pressure usually associated with glaucoma is caused by blockages in the eye’s fluid drains. No one knows yet why the blockages form. Symptoms are occasionally present and should be taken as warning signs that glaucoma may be developing; these include blurred vision, loss of peripheral vision, halo effects around lights, and painful or reddened eyes. Most people with glaucoma have no symptoms at all. People at the greatest risk include those who are over the age of 40, diabetic, near-sighted, African-American, or who have a family history of glaucoma.
Once diagnosed, glaucoma can be controlled. Treatments to lower pressure in the eye include non-surgical methods such as prescription eye drops and medications, laser therapy, and surgery.
Laser Treatment of Glaucoma
SLT (Selective Laser Trabeculoplasty)
SLT has become increasingly popular as an intermediate step between drugs and traditional surgery. This procedure takes between 10 and 15 minutes and is painless. The laser beam (a high-energy light beam) is focused upon the eye’s drain. Contrary to what many people think, the laser does not bum a hole through the eye. Instead, the eye’s drainage system is changed in very subtle ways so that aqueous fluid can pass more easily out of the drain, thus lowering IOP.
You may go home and resume your normal activities following laser. After this procedure, many patients respond well enough to be able to avoid or delay surgery. While it may take a few weeks to see the full pressure-lowering effect of this procedure, during which time you may have to continue taking your medications, many patients are eventually able to discontinue some of their medications. This, however, is not true in all cases. Your doctor is the best judge in determining whether you will still need medication. Complications from lasers are minimal, which is why this procedure has become increasingly popular and is sometimes recommended before eye drops in some patients. It is especially a great first option for people who find it difficult to comply with the strict, regular schedule needed for administering eye drops or find it difficult to instill drops in their eyes due to tremors or arthritis.
Laser Iridotomy
This procedure is used to make an opening through the iris, allowing aqueous fluid to flow from behind the iris directly to the anterior chamber of the eye. This allows the fluid to bypass its normal route. LPI is the preferred method for managing a wide variety of angle-closure glaucomas.
Cycloablation
Two laser procedures for open-angle glaucoma involve reducing the amount of aqueous humor in the eye by shrinking part of the ciliary body, which produces the fluid. These treatments are usually reserved for use in eyes that either have elevated eye pressure after having failed other more traditional treatments, including filtering surgery, or those in which filtering surgery is not possible or advisable due to the shape or other features of the eye. Transscleral cyclophotocoagulation uses a laser to direct energy through the outer sclera of the eye to reach and shrink portions of the ciliary body without causing damage to the overlying tissues. With endoscopic cyclophotocoagulation (ECP), the instrument is placed inside the eye through a surgical incision so that the laser energy is applied directly to the ciliary body tissue.
Traditional Glaucoma Surgery
When medications and laser therapies do not adequately lower eye pressure, surgical treatment may be needed to control the eye pressure. The most common of these operations is called a Trabeculectomy, which is used in both open-angle and closed-angle glaucomas. In this procedure, the surgeon creates a tiny passageway from the inside to the outside of the eye to drain the fluid into a cyst or bleb under the upper eyelid. The surgically created drainage hole can close with time, and the eye pressure can rise again. This happens because the body tries to heal the new opening as if it were an injury. Many surgeons perform trabeculectomy with an anti-fibrotic agent that is placed on the eye during surgery and reduces such scarring during the healing period. The most common anti-fibrotic agents are Mitomycin-C and 5-Fluorouracil.
About 50 percent of patients no longer require glaucoma medications after surgery for a significant length of time. A trabeculectomy is usually an outpatient procedure. The number of post-operative visits to the doctor varies, and some activities, such as driving, reading, bending, and heavy lifting, must be limited for two to four weeks after surgery.
Drainage Implant Surgery
Several different microscopic devices have been developed to aid the drainage of aqueous humor out of the anterior chamber and lower the eye pressure. All of these drainage devices share a similar design, which consists of a small silicone tube that extends inside the eye. The tube is connected to one or more plates, which are sutured to the surface of the eye, usually not visible. Fluid is collected on the plate and then absorbed by the tissues in the eye. This type of surgery is thought to lower the eye pressure less than trabeculectomy but is preferred in patients whose pressure cannot be controlled with traditional surgery or who have previous scarring.
Microinvasive Glaucoma Surgery (MIGS)
New technologies and devices, known as MIGS, aim to lower eye pressure in a much safer manner with rapid recovery and minimal restrictions. Instead of creating an artificial drain in the eye, they unclog the natural drainage system of the eye and enhance drainage. The latest MIGS approaches include the iStent, Trabectome, Viscocanaloplasty. Currently, MIGS approaches and techniques are best suited to glaucoma patients with early to moderate disease, preferably in combination with cataract surgery.
There are several advantages offered by the MIGS procedures. These are bleb-independent procedures that avoid the major complications of traditional surgery, such as lifetime risk of infection with subsequent loss of vision or loss of an eye, long-term risk of leaks, and too low eye pressure.
Additionally, they are usually performed at the time of cataract surgery with similar recovery, postoperative drop regimen, and restrictions of activity as cataract surgery alone. A large majority of patients can not only achieve independence from eyeglasses but minimize or eliminate glaucoma eye drops.
While there is no cure for Glaucoma just yet, it can be controlled and stabilized by maintaining the eye pressure in a safe range. Contrary to previous belief, there is no magic or miracle cutoff for safe eye pressure. Instead, it is an individualized number or range, which depends on the severity of glaucoma damage, age, corneal thickness, besides a host of other factors. All current treatments in Glaucoma are directed towards lowering the eye pressure. It is important to maintain a regular schedule of eye pressure checks, dilated exams of the optic nerve, and visual field testing in order to diagnose and treat subtle worsening of glaucoma damage.
