contact us | 303-682-3396
 

Glossary

Laser Vision Correction

Ophthalmic Plastic Surgery

 

Excimer Laser

(EKS-ih-mur). Class of ultraviolet lasers that removes tissue accurately without heating it. In refractive corneal surgery, controlled by computer to make precise pre-programmed shavings of eye tissue to produce a given optical correction. Used for photorefractive keratectomy (PRK); combined with automated lamellar keratoplasty (ALK) to produce LASIK (laser in situ keratomileusis).

Back to Top

 

Laser

Acronym: Light Amplification by Stimulated Emission of Radiation. High energy light source that uses light emitted by the natural vibrations of atoms (of a gas or solid material) to cut, burn or dissolve tissues for various clinical purposes: in the retina, to treat diabetic retinopathy and macular degeneration, to destroy leaking and new blood vessels (neovascularization); on the iris or trabecular meshwork, to decrease pressure in glaucoma; after extracapsular cataract extraction, to open the posterior lens capsule.

Back to Top

 

LASIK

Laser Assisted In-Situ Keratomileusis (LASIK) is a brief outpatient microsurgical procedure that reduces the amount of nearsightedness by flattening or steepening the cornea of the eye. Since 1949, Dr. Jose Barraquer of Bogota, Columbia had been working on a procedure to reshape the cornea by removing an outer layer of the cornea, reshaping it, and replacing it onto the eye. In the late 1980's Dr. Luis Ruiz, also of Bogota, refined the corneal shaping technique by introducing the Automated Corneal Shaper. The microkeratome is used to shave a thin flap from the front surface of the cornea. This is called Lamellar surgery because the cornea, similar to a piece of plywood, is composed of many layers and this flap of tissue is composed of only a few layers of the anterior cornea.

In the mid 1980's the Excimer Laser was developed for the correction of refractive errors. This is a cold laser that utilizes ultraviolet light energy to reshape the corneal surface that it touches. It is considered to be extremely precise and predictable. This procedure is called Phototheraputic Keratectomy or PRK, and while a large number of patients have undergone this procedure with very good results, this procedure has some limitations. Following surface treatment with the Excimer laser, there is a raw area left on the surface of the cornea that must heal before clear vision can occur. This raw area also can result in increased pain, blurring, and variable effect of healing which can affect the amount of correction achieved. Also, a layer of the cornea called Bowman's membrane is removed; this can cause increased corneal haze and scarring in higher amounts of myopia. Like RK, PRK is also more variable and unpredictable in higher amounts of nearsightedness. The F.D.A. (Food and Drug Administration) approved the Excimer laser in 1995 for surface PRK in low to moderate amounts of nearsightedness.

In 1991 the Microkeratome was combined with the Excimer laser and the current technique of LASIK was developed. During the procedure, a suction ring is placed onto the eye to stabilize it, and the microkeratome is used to form a thin flap of corneal tissue. The Excimer laser is then used to gently sculpt the cornea, removing a very precise amount of tissue from the cornea underneath this flap, and the flap is carefully replaced back into position without sutures. By removing a variable amount of tissue from the middle of the cornea, this causes the overlying flap to drape down into the space flattening the central cornea. This central area of cornea, which is removed with the laser, varies in thickness depending on the patients amount of nearsightedness. LASIK has the advantage of laser precision, without leaving a raw surface of the cornea. This translates into decreased post-operative discomfort, and quicker visual recovery with LASIK over PRK. For astigmatism, since the curvature of the cornea is steeper in one part of the cornea and flatter in another, like a football, the laser also can treat the steeper areas of the cornea more than the flatter areas effectively reshaping the cornea into a more rounded or spherical shape. Every eye is unique, therefore careful preoperative examinations are conducted to develop a surgical plan for each patient. The VISX excimer laser has been approved for the treatment of nearsightedness, farsightedness, and astigmatism. Recently the Visx Excimer laser was also approved for LASIK by the F.D.A.. The VISX laser is one of only 2 lasers which is approved for both PRK and LASIK.

We now use the newest Visx S-3 Eye Tracker. This means that the patient does not have to focus on a beam of light. It will automatically track the eye for you eliminating worry and you have the peace of mind of the most accurate results.

Back to Top

 

Overflow Tearing and Chronic Eye Infections in Infants

Babies frequently develop infected eyes with overflow tearing. It has been reported that almost one-third of newborn infants have one or both eyes that water at birth. These eyes overflow with tears and mucus. Often the lashes are stuck together after sleep, and the eye(s) may become chronically infected. Ophthalmologists refer to overflow tearing as congenital stenosis of the nasal lacrimal drainage system.

Back to Top

 

PRK (Photorefractive Keratectomy)

The Excimer laser has been used very successfully to treat patients with myopia since 1987. Since that time over 1,500,000 patients have been treated with the laser. Photorefractive Keratectomy or PRK is a method to precisely sculpt the surface of the cornea using a state of the art, computer controlled, invisible, cool beam of light energy to reshape the corneal surface that it touches. Since October of 1995, the FDA has approved PRK for the treatment of low to moderate amounts of myopia and astigmatism. PRK is considered to be safe and predictable. Each pulse of the laser removes approximately 25 microns (0.00004 of an inch) of corneal tissue, which makes it extremely accurate. The more removed, the more refractive effect is achieved. In less than a minute, the laser removes less than 50 microns of tissue, which is about ½ the thickness of a human hair, to achieve the proper correction. After this treatment, most people report that they no longer need to depend on glasses or contact lenses. In the clinical trials, 64% of people reported 20/20 or better vision after PRK and more than 93% of people could see 20/40 or better, reporting that they were much more functional and could even drive a car without glasses or contact lenses. Although vision without glasses improved for all eyes, some still needed glasses or contact lenses for some tasks after surgery. Read More

Back to Top

 

RK & AK (Radial Keratotomy and Astigmatic Keratotomy

Radial Keratotomy (RK) and Astigmatic Keratotomy (AK) work in a manner similar to each other. Radial Keratotomy (RK) is a brief outpatient microsurgical procedure that reduces the amount of near-sightedness by flattening the cornea of the eye. During the procedure, a series of microscopic incisions are made in a radial, or spoke-like, fashion in the cornea around a centrally undisturbed portion of the cornea called the optical zone. These incisions change the shape of the cornea, allowing images to be focused properly onto the retina or back of the eye. These incisions vary in length and number depending on the patient's age and amount of near-sightedness. For astigmatism, since the curvature of the cornea is steeper in one part of the cornea and flatter in another, like a football, peripheral incisions are placed in the steepest part of the cornea causing the cornea to "round out." Every eye is unique, therefore careful preoperative examinations are conducted to develop a surgical plan for each patient. Since its introduction to the United States in 1978, more than 1,500,000 RK procedures have been performed.

Back to Top

 

Thyroid Eye Disorders

The thyroid gland, located in the neck, produces thyroid hormone which helps regulate our metabolism. It may produce either too much thyroid hormone (hyperthyroidism) or too little (hypothyroidism). Imbalance in either direction can cause eye and vision problems.

Symptoms of hyperthyroidism include fatigue, fast heartbeat, weight loss, heat intolerance, fine hair, and diarrhea. Hypothyroidism may also cause fatigue, but with slow heartbeat, constipation, and weight gain.

Back to Top

 

Tearing in Adults

Small glands, located in the surface tissue on the white of the eye and lining the eyelids, constantly produce small quantities of tears to keep the eye healthy and lubricated. The lacrimal gland, a larger gland located in the upper eyelid, responds to emotion or eye irritation by producing larger quantities of tears.

In some people, tears well up in the eye because too many tears are produced or because the tears are not draining properly. Excess tears give the eye a moist appearance and can collect along the border of the lower lid and overflow onto the cheek.

Back to Top

 

YAG Laser

Laser that produces short pulsed, high-energy light beam to cut, perforate, or fragment tissue.

Back to Top

Excerpted from Dictionary of Eye Terminology, copyright 1990-2006

by Barbara Cassin and Triad Communications.  Reprinted with permission.