LASIK & Laser Vision Correction

How laser vision correction works

The planned correction is programmed into the laser's computer. The laser gently sculpts the corneal surface in a pattern which corrects your vision error.

• Myopia (nearsightedness): the center of the cornea is slightly flattened, bringing the focus back to the retina of a long, nearsighted eye.
• Hyperopia (farsightedness): the cornea around the central zone is flattened, steepening the central cornea and bringing the focus forward to the retina of a short, farsighted eye.
• Astigmatism: an oval reshaping is performed to make the eye more round.

The LASIK procedure

LASIK uses an excimer laser to reshape the cornea so that images focus directly on the retina. The laser alters the shape of the cornea in increments of less than 0.25 microns — one-tenth the thickness of a human hair.

A thin flap, slightly thicker than a human hair, is created and moved to the side temporarily. The excimer laser removes a minute amount of cornea beneath the flap; the pattern removed depends on the correction necessary. The flap is then placed back over the cornea, where it adheres securely within minutes.

PRK

Photo-refractive keratectomy (PRK) is similar to LASIK except there is no flap creation. Instead, the surface cells are removed with the laser or a special instrument, then the laser thins and reshapes the cornea just as with LASIK. The surface cells must grow back over the center of the cornea, so healing in terms of comfort and vision takes longer than with LASIK — but the long-term results are similar.

The laser eye surgery experience

The laser procedure is performed at a local laser center. You wear normal street clothes. Drops are the only anesthesia; sedation is not necessary, but you may take an oral tranquilizer. Your eyelids and lashes are cleansed for sterility and your lids are gently held open. You look at a blinking light which helps keep your eye positioned, and the laser's tracking technology follows even the tiniest natural eye movements.

During the flap creation phase you feel a sensation of pressure and a grayness of vision. Then the laser is used and you will hear a rapid clicking sound. The flap is replaced and takes about two minutes to adhere. Drops are placed in your eyes to aid healing and clear protective shields are placed over your eyes. The procedure takes under 10 minutes per eye.

Recovery

Discomfort is rare and minimal. Usually vision is immediately improved but may fluctuate for several weeks. For a week a shield is worn over the eye at night until complete healing occurs, and the eyes must not be rubbed to protect the flap. Drops are used for one week or less with LASIK, and up to several weeks with PRK. Retreatment is occasionally necessary and is performed once the eye is stable — usually no sooner than three months.

What to expect

Laser vision correction greatly reduces dependence on glasses and contact lenses and usually results in a dramatic life change. Between 95% and 98% of patients achieve legal driving vision without glasses (20/40 or better), and two-thirds of those see 20/20 or better. As with any surgical procedure there are risks, but the complication rate is very low.

Glasses may be necessary for fine-tuning vision in certain conditions (night driving, computer work, heavy reading). People over forty usually require reading glasses unless one eye is purposefully left slightly nearsighted ("monovision"). Most people prefer both eyes as sharp as possible for distance and use reading glasses when necessary.