Glaucoma : Laser Surgery

by Food and Drug Administration (FDA)

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Laser Surgery

Some patients may require traditional scalpel surgery, but in recent years laser operations have come into favor. Laser surgery can't repair existing damage, but it usually stops glaucoma, both in acute emergencies and open-angle cases. It may involve minor side effects, including restrictions on wearing contact lenses, but its risks are quite low. Sometimes it must be repeated if its drainage openings begin to close.

Light amplification by stimulated emission of radiation — LASER — sends a uniform, focused beam of light to pinpoint applications. In glaucoma surgery for angle closure, the laser creates a minute hole in the iris, just large enough to allow aqueous fluid to flow freely.

Despite its high-tech wizardry, most laser surgery for glaucoma seems quite undramatic to the patient undergoing it. (See "Light for Sight," FDA Consumer, July-August 1990.) An acute glaucoma patient peers into the eyepiece on one side of a boxy device while a surgeon manipulating controls peers into an eyepiece opposite. There's little or no additional pain, often not even unpleasant sensation, as the surgeon beams an intense beam of light to "burn" an escape channel for aqueous fluid, usually in the upper edge of the iris.

The Nd:YAG (neodymium:yttrium aluminum garnet crystal) laser has emerged with several advantages over the earlier argon laser, including lower energy requirement, fewer pulses, reduced obstruction, and a lower rate of subsequent closure of incisions. Its portability allows the YAG laser to serve even remote Inuit villages in Alaska previously inaccessible for sophisticated optical surgery.

No wonder that laser surgery in just 25 years has largely displaced traditional scalpel surgery, which involves hospital stays and higher risks. Its low risk allows use earlier in the course of the disease, when its potential benefit is greater.

On the Horizon

Diligence in countering early the subtle onset of glaucoma is the best protection. Research is making such diligence easier.

Ongoing research aims to simplify dosage demands while reducing side effects. For instance, the nuisance of taking preventive eye medications several times a day discourages some people from protecting themselves fully. Work is under way to perfect a once-a-week eye preparation and one-a-day eye drops to ease the use of topical eye medications. Already, dispenser tips that measure more consistent doses of eye drops are improving their use.

Even the standard course of escalating treatment for common glaucoma is being reconsidered. The practice more common in Europe suggests that reversing this order by starting with surgery may be promising. In August 1993, the National Eye Institute announced the Collaborative Initial Glaucoma Treatment Study to compare the long-term effect of treating newly diagnosed primary open-angle glaucoma with standard treatment versus immediate laser surgery.

Risks and Responses

Elevated eye pressure and detectable damage to the optic nerves are significant risk indicators for glaucoma. To prevent needless blindness from undetected, untreated glaucoma, the American Academy of Ophthalmology offers additional guidelines for assessing risk.

The academy's guidelines include comparing the diameter of the eye's cup to that of its disc to obtain a physical gauge of the likelihood of glaucoma. Estimates are made vertically along an imaginary line drawn through the center of the disc from the 12 o'clock to the 6 o'clock position. The normal optic nerve illustrated with a small cup has a cup-to-disc ratio of less than 0.5, indicating a low probability of glaucoma. Moderately advanced cupping, with a cup-to-disc ratio of 0.6 to 0.8 and a neural rim starting to thin, increases the suspicion of glaucoma. Almost total cup-to-disc ratio of 0.9, exhibiting a very thin neural rim, creates a high level of glaucoma suspicion.

People at risk of glaucoma should faithfully have eye checkups at the intervals recommended by their ophthalmologists. Everyone over 40 should have a full eye examination every two years, regardless of risk factors; African Americans should be vigilant after age 30. Adult relatives of persons diagnosed with glaucoma should have regular eye checkups. Glaucoma seems to be hereditary, and even cousins may be at risk if you are.

Glaucoma treatment decisions are personalized. Even eye color may affect the rate at which a person absorbs eye medications.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.