Glaucoma is a complicated disease in which damage to the optic nerve leads to progressive, irreversible vision loss. Glaucoma is the second leading cause of blindness.
What is Glaucoma?
Glaucoma is a group of eye diseases causing optic nerve damage. The optic nerve carries images from the retina, which is the specialized light sensing tissue, to the brain so we can see. In glaucoma, eye pressure plays a role in damaging the delicate nerve fibers of the optic nerve. When a significant number of nerve fibers are damaged, blind spots develop in the field of vision. Once nerve damage and visual loss occur, it is permanent. Most people don’t notice these blind areas until much of the optic nerve damage has already occurred. If the entire nerve is destroyed, blindness results. Glaucoma is a leading cause of blindness in the world, especially in older people. Early detection and treatment by your ophthalmologist are the keys to preventing optic nerve damage and vision loss from glaucoma.
What Causes Glaucoma?
The exact causes of optic nerve damage from glaucoma is not fully understood, but involves mechanical compression and/or decreased blood flow of the optic nerve. Although high eye pressure sometimes leads to glaucoma, many people can also develop glaucoma with “normal” eye pressure.
What are the Warning Signs
- Unusual trouble adjusting to dark rooms
- Difficulty focusing on near or distant objects
- Squinting or blinking due to unusual sensitivity to light or glare
- Change in color of iris
- Red-rimmed, encrusted or swollen lids
- Recurrent pain in or around eyes
- Double Vision
- Dark spot at the center of viewing
- Lines and edges appear distorted or wavy
- Excess tearing or “watery eyes”
- Dry eyes with itching or burning; and
- Seeing spots, ghost-like images.
When operative surgery is needed to treat glaucoma, your ophthalmologist will use a microscope and specialized instruments to create a new bypass drainage channel for the eye fluid to leave the eye. The new channel helps to lower the eye pressure. Surgery will be recommended only if your ophthalmologist feels the benefit of a lower eye pressure achieved with an operation outweighs possible complications and/or further progression of optic nerve damage.
Laser surgery has become increasingly popular as an intermediate step between drugs and traditional 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 (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 is able to pass more easily out of the drain, thus lowering IOP.
You may go home and resume your normal activities following surgery. Your doctor will likely check your IOP one to two hours following laser surgery. 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 of determining whether or not you will still need medication. 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 is a newer laser that 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. Some authors have reported that a second repeat application of SLT or SLT after prior ALT is effective at lowering IOP.
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. This laser is most often used to treat an anatomically narrow angle and prevent angle-closure glaucoma attacks.
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 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. 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.