The word "laser" is an acronym for light amplification by stimulated emission of radiation. In most lasers used in ophthalmology, an electric current is passed through a tube that contains an amplifying medium, usually a gas or solid material, which serves to intensify the energy. This energy is emitted as a narrow light beam which, when focused through a microscope, will either cut, burn, or dissolve various tissues.
Different types of lasers emit specific colors of light and are used to treat various eye problems. The lasers are usually named for the amplification materials used. For instance, the carbon dioxide laser is called a CO2 laser, while the YAG laser contains a solid material made up of yttrium, aluminum, and garnet.
Ophthalmic lasers allow precise treatment of a variety of eye problems without risk of infection. Most laser procedures are also relatively painless and can be done on an outpatient basis. This combination of safety, precision, convenience, and reduced cost make lasers one of the most successful medical tools available to physicians.
The Excimer laser is precise. Each pulse of the laser removes about 1/500 of the thickness of a human hair. Its precise depth and area control are significant in surgical applications such as refractive vision correction.
Cataract patients often have the misconception that a YAG laser is used to remove their cataracts, but no lasers are used in cataract surgery. This misconception occurs because up to 75 percent of cataract patients develop a condition known as posterior capsular opacification, a clouding of the residual lens capsule left in place after cataract surgery. This gradual loss of vision resembles the symptoms of cataract development, making some people believe that their cataracts have grown back.
The YAG laser is commonly used to vaporize a portion of the capsule, allowing light to pass through to the retina. The procedure is completely painless, takes only a few minutes in the office, and is effective in eliminating the cloudy condition.
The CO2 laser is used by ophthalmic plastic surgeons to remove fine wrinkles from around the eyes. This laser precisely removes the outermost layer of skin and the underlying dermis, allowing the regrowth of wrinkle-free new skin.
The Erbium laser is also being used in a promising new clinical procedure to emulsify the eye's natural lens during cataract surgery. Most cataract surgeons currently use a piece of equipment called a phacoemulsifier to break up and remove the cloudy lens. The Erbium laser was chosen for the new technique because of its high absorption rate in water, a primary component of the eye's natural crystalline lens.
Retinal detachment is another serious eye problem that can be treated by the argon laser. The laser is used to weld the detached retina to the underlying choroid layer of the eye.
Several forms of glaucoma, which is a leading cause of blindness, are also treated with argon lasers. The very serious angle closure glaucoma, for instance, is sometimes treated by using the laser to create a tiny opening in the iris, allowing excess fluid inside the eye to drain to reduce pressure.
Macular degeneration, a severe condition that affects central vision in older adults, is sometimes treated with an argon or krypton laser. In this treatment, the laser is used to destroy abnormal blood vessels so that hemorrhage or scarring will not damage central vision.
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