Treating Glaucoma

Glaucoma can be treated with eye drops, pills, laser surgery, traditional incisional surgery, newer minimally invasive surgical alternatives or a combination of these methods. The goal of any treatment is to prevent loss of vision, as vision loss from glaucoma is irreversible. The good news is that glaucoma can be managed if detected early, and that with medical and/or surgical treatment, most people with glaucoma will not lose their sight.

Taking medications regularly, as prescribed, is crucial to preventing vision-threatening damage. That is why it is important to discuss side effects with your doctor. While every drug has some potential side effects, it is important to note that many patients experience no side effects at all. You and your doctor need to work as a team in the battle against glaucoma. Your doctor has many options. They include:

Eye Drops

It is important to take your medications regularly and exactly as prescribed if you are to control your eye pressure. Since eye drops are absorbed into the bloodstream, tell your doctor about all medications you are currently taking. Ask your doctor and/or pharmacist if the medications you are taking together are safe. Some drugs can be dangerous when mixed with other medications. To minimize absorption into the bloodstream and maximize the amount of drug absorbed in the eye, close your eye for one to two minutes after administering the drops and press your index finger lightly against the inferior nasal corner of your eyelid to close the tear duct which drains into the nose. While almost all eye drops may cause an uncomfortable burning or stinging sensation at first, the discomfort should last for only a few seconds.

Pills

Sometimes, when eye drops don’t sufficiently control IOP, pills may be prescribed in addition to drops. It is important to share this information with all your other doctors so they can prescribe medications for you which will not cause potentially dangerous interactions. Pills, which have more systemic side effects than drops, also serve to turn down the eye’s faucet and lessen the production of fluid. Usually taken from two to four times daily, these medications are very useful on a short-term basis for most patients.  For longer periods of time the usage can be a problem because they can reduce one’s potassium level or create kidney stones. Your ophthalmologist and internist should work together to be sure these patients are monitored for electrolyte levels and related issues.

Surgical Procedures

When medications do not achieve the desired results, or have intolerable side effects, your ophthalmologist may suggest surgery.

Laser Surgery

Laser surgery has become increasingly popular as an intermediate step between medications and traditional incisional surgery though the long-term success rates are variable. The most common type performed for open-angle glaucoma is called trabeculoplasty. This procedure takes between 10 and 15 minutes, is painless, and can be performed in either a doctor’s office or an outpatient facility. The laser beam is focused upon the eye’s drain. Contrary to what many people think, the laser does not burn a hole through the eye. Instead, the eye’s drainage system is changed in very subtle ways so that aqueous fluid is able to pass more easily out of the drain, thus lowering IOP.

You may go home and resume your normal activities following laser surgery. Your doctor will likely check your IOP one to two hours following laser 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 of determining whether or not you will still need medications. Complications from laser are minimal, which is why this procedure has become increasingly popular and some centers are recommending the use of laser before drops in some patients.

Argon Laser Trabeculoplasty (ALT) — for open-angle glaucoma.

The laser treats the trabecular meshwork of the eye, increasing the drainage outflow, thereby lowering the IOP. In many cases, medication will still be needed. Usually, half the trabecular meshwork is treated first. If necessary, the other half can be treated as a separate procedure. This method decreases the risk of increased pressure following surgery. Argon laser trabeculoplasty has successfully lowered eye pressure in up to 75 percent of patients treated. This type of laser can be performed only two to three times in each eye over a lifetime.

Selective Laser Trabeculoplasty (SLT) — for open-angle glaucoma.

SLT uses very low levels of energy. It is termed “selective” since it leaves portions of the trabecular meshwork intact. For this reason, it is believed that SLT, unlike other types of laser surgery, may be safely repeated.

Laser Peripheral Iridotomy (LPI) — for angle-closure glaucoma.

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 that have some degree of pupillary blockage. It is most often used to treat an anatomically narrow angle and prevent angle-closure glaucoma attacks.

Cycloablation.

Two laser procedures for open-angle glaucoma involve reducing the amount of aqueous humor in the eye by destroying part of the ciliary body, which produces the fluid. These treatments are usually reserved for use in eyes that either have elevated IOP 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 (e.g.MicroPulse P3) uses a laser to direct energy through the outer sclera of the eye to reach and destroy portions of the ciliary processes, without causing damage to the overlying tissues. It requires sedation and is typically done in the operating room. With endoscopic cyclophotocoagulation (ECP), usually done with cataract surgery, 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 Incisional Surgery

Trabeculectomy.

When medications and laser therapies do not adequately lower eye pressure, doctors may recommend conventional surgery. 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 passage in the sclera (the white part of the eye) for draining excess eye fluid. A flap is created that allows fluid to escape, but which does not deflate the eyeball. A small bubble of fluid called a “bleb” often forms over the opening on the surface of the eye, which is a sign that fluid is draining out into the space between the sclera and conjunctiva. Occasionally, the surgically created drainage hole begins to close and the IOP rises again. This happens because the body tries to heal the new opening, as if it was an injury. Most 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 agent is Mitomycin-C. Another is 5-Fluorouracil, or 5-FU.

About 50 percent of patients no longer require glaucoma medications after surgery for a significant length of time. Thirty-five to 40 percent of those who still need medication have better control of their IOP. 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 devices, sometimes called aqueous shunts (e.g. Baerveldt and Ahmed shunts), have been developed to aid the drainage of aqueous humor out of the anterior chamber and lower IOP. All of these drainage devices share a similar design which consists of a small silicone tube that extends into the anterior chamber of 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 IOP less than trabeculectomy but is preferred in patients whose IOP cannot be controlled with traditional surgery or who have previous scarring. The ExPress mini glaucoma shunt is a stainless steel device that is inserted into the anterior chamber of the eye and placed under a scleral flap. It lowers IOP by diverting aqueous humor from the anterior chamber.

Minimally Invasive Surgical Alternatives.

Minimally invasive glaucoma surgery (MIGS) is one of the new and exciting developments in the treatment of glaucoma. It has long been a goal of glaucoma surgeons to perform less invasive procedures that minimize the postoperative complications of most standard glaucoma surgeries and lower the risk of infection while providing the same reduction in the dependence upon medications as traditional incisional filtration surgery.

Among the earlier introductions of non-penetrating surgical alternatives was the Trabectome and canaloplasty. The Trabectome is a probe-like device that is inserted into the anterior chamber through the cornea. The procedure uses a small probe that opens the eye’s drainage system through a tiny incision and delivers thermal energy to the trabecular meshwork, reducing resistance to outflow of aqueous humor and, as a result, lowering IOP. In canaloplasty, the physician uses an extremely fine catheter to clear the drainage canal.

Today there are numerous FDA-approved MIGS devices. Some other devices that target the trabecular meshwork – the conventional outflow path –are the iStent, Kahook Dual Blade, Hydrus microstent, and Ab-interno Canaloplasty (ABiC).

Another target area is the subconjunctival space, just under the conjunctiva, which is a clear membrane that covers the white of the eye. The only device currently approved for that is the Xen Gel Stent, with the InnFocus Micro Shunt on the horizon for FDA approval. A third generation iStent, iStent Supra, is intended to be placed in the supraciliary space (next to the uvea).

Each MIGS procedure involves implanting a tiny device to allow fluid to drain from the eye, reducing internal pressure. Some devices are FDA approved for implantation only at the time of cataract surgery.  Clinical research has shown that by performing a MIGS procedure at the same time as removing the cataract, the surgeon can usually bring the patient’s mild to moderate glaucoma under better control, lower the IOP and/or reduce the medications required to control the IOP.

A few other MIGS devices are approved for use apart from cataract surgery, among them the Dual Blade and Trabectone, and the Xen Gel Stent.