What is a laser?

The word laser stands for "Light Amplification by Stimulated Emission of Radiation."  A laser is a concentrated beam of light, created when an electric current passes through a special material.

The name and the color of the laser depend on the type of special material that is used:

• Argon gas - blue-green light
• Krypton gas - red or yellow light
• YAG (yttrium-aluminum-garner) - invisible infrared light
• Argon - fluoride (excimer) - invisible ultraviolet light

How does the laser work?

There are two different ways that lasers are used to treat eye diseases.

Thermal lasers:  The light is converted to heat when it reaches the eye.

The heat is used to:

• Seal blood vessels (veins and arteries) that are bleeding or leaking fluids
• Destroy abnormal tissue such as a tumor
• Bond the retina to the back of the eye
• Open the eye's filtration system for glaucoma treatment
• Create an opening in the iris for treatment of narrow angle glaucoma

Photodisruptive lasers:  The light cuts or sculpts the tissue, similar to a knife.

The beam of light is used to:

• Cut thin membranes inside the eye that are blocking vision
• Change the shape of the eyes surface

What are the advantages of using ophthalmic lasers?

Laser surgery of the eye has several advantages:

• There is no risk of infection from the laser light
• Laser surgery can be performed in an outpatient setting, allowing you to go home shortly after the procedure is finished
• The surgeon has great precision and control

Which eye diseases can be treated with laser surgery?

Diseases of the retina

Retinal tears or holes:  The retina is the inner layer of the eye that senses light and helps you to see.  If the retina tears, it can separate from the back wall of the eye.  This is called a detached retina and it can cause you to lose sight.  Symptoms of retinal tears include:

• Sudden flashes of light
• "Floaters" or specks in your vision

Most retinal tears can be treated with the argon or krypton laser, if they are found before the retina detaches.  The laser helps bond the retina to the wall of the eye, preventing a retinal detachment.

If the retinal detachment has already occurred, the laser may be used as part of a surgical repair of the detachment.

Diabetic retinopathy:  Eye disease from diabetes is a major cause of vision loss.  Diabetes can cause blood vessels in the retina to grow abnormally.  The vessels can leak fluid (macular edema) or bleed inside the eye.

Laser surgery to treat diabetic retinopathy:

• Seals leaking blood vessels to reduce macular edema, helping to prevent further vision loss
• Slows or stops growth of abnormal blood vessels, decreasing the chance of bleeding in the eye

Macular degeneration:  The macula is the small, central area of the retina that allows us to see fine details clearly.  Macular degeneration affects your central or reading vision.

Most people have "dry" macular degeneration, which cannot be helped by laser surgery.

A few people have "wet" macular degeneration.  With this condition, abnormal blood vessels cause bleeding and scarring of the macula.  In certain cases, these people may be treated with the argon or krypton laser.  The laser seals the blood vessels to prevent further damage. 

There are other retina problems that can be treated with the laser, including:

• Retinal vein occlusions
• Histoplasmosis
• Central serous retinopathy
• Some tumors of the eye

After cataract surgery

After a cataract has been removed, the capsule of the lens sometimes becomes cloudy.  The neodymium - YAG laser can open up this cloudy membrane and restore vision. 

The laser is not used to remove cataracts.

Glaucoma

Glaucoma is a disease of the optic nerve.  This nerve sends images from the eye to our brain and allows us to see.  Glaucoma is the second most common cause of blindness in the U.S., and the leading cause of legal blindness among African Americans.

Glaucoma damages the optic nerve, usually because the fluid pressure inside the eye is too high.  Loss of vision from glaucoma can often be prevented if your ophthalmologist discovers the disease before much damage occurs to the optic nerve.

Glaucoma must be detected early if treatment is to be successful.

Eye drops or pills are the usual way to treat glaucoma.  If they do not control the pressure within the eye, laser surgery may be used to lower pressure.

Refractive surgery

In procedures called photorefractive keratectomy, (PRK) and laser in situ keratomileusis (LASIK), the excimer laser is used to sculpt the cornea and reduce or eliminate the need for eye-glasses or contact lenses.

Summary

Laser surgery has been one of the great advances in treating eye diseases.  The success of the laser depends on the type of eye disorder.

In most situations, laser surgery helps prevent further loss of sight, but will not provide great improvement in vision.  In a few situations, such as YAG laser surgery, PRK, or LASIK, vision may be restored to normal.

Your ophthalmologist (Eye M.D.) will discuss the risk and benefits that laser treatment can offer.

Copyright 1998© American Academy of Ophthalmology®