The eyes are vital sensory organs, but unfortunately they grow weaker over time. There are also many people who have some sort of eye defect that affects their vision. It is possible to correct many of these conditions with the use of lasers, which are used to change the shape of the eye to correct vision.

Shortsightedness or myopia, and farsightedness or hyperopia are caused by the eye being too short or too long when measured from the side. Normally, the lens of the eye focuses the image which then lands on the sensory portion of the eye. Under myopia or hyperopia, the focal point is either behind or before the sensory portion, meaning that the image landing on the inside surface of the eye is out of focus. Astigmatism is caused by irregularities in the shape of the cornea or lens. Laser surgery is used in extreme cases of any of these conditions, and also chosen by some who would rather not wear eyeglasses or contact lenses.

The most common corrective eye surgery using lasers is called LASIK or Laser-Assisted In Situ Keratomileusis. In this procedure, the shape of the cornea is changed by using short bursts of low-power laser light to cut a flap of corneal matter. Then the underlying tissue is reshaped with an Excimer laser which vaporizes tissue with precision. Finally, the lifted flap is repositioned. A recovery period involving antibiotics, anti-inflammatory eye drops, and darkened eye shields follows the operation. Sleeping more is often recommended, and goggles are given to prevent rubbing the eyes. Artificial tears may also be prescribed to prevent dryness.

The older procedures known as LASEK or Laser-Assisted Sub-Epithelial Keratectomy, and Photorefractive Keratectomy or PRK, are not performed as often as LASIK. These procedures work on the surface of the cornea instead of the deeper layers as in LASIK. After mapping the surface of the eye with a contouring device, the laser is then used to remove the outer layers of the cornea. Recovery time can be longer after these procedures, and there may be more pain as well. The advantage is that there is no risk of corneal flap dislocation like in LASIK.

Corrective Laser eye surgeries are performed with the patient awake, though a mild sedative and anesthetic eye drops. This may seem intimidating and more than a little scary to some, especially since a laser is involved in such a delicate surgery. The solution was to integrate the laser with a computer that tracks eye movement and compensates the laser’s positioning to achieve consistent surgical behavior. Also, if the eye moves out of range, the laser is disabled until such time that the eye is re-centered. The tracking happens at rates up to 4000 times a second.

There are some complications associated with these procedures, such as under-correction or over-correction, pain, corneal haloes, starbursts, corneal flap dislocations, dry eyes, recurrence of myopia, reduced acuity in low-light conditions, and scarring. Regardless, there are many who feel the risks are justified and undergo these operations.