How does laser eye surgery / treatment work?
Laser eye surgery is performed using an excimer laser. This laser emits pulses of ultraviolet light, a special type of light energy invisible to the human eye. Each time a light pulse is emitted, a very subtle layer of cornea is removed, to slightly alter its curvature. Specialist medical software then allows the computer to determine the pattern of the pulses to remove the necessary corneal tissue.
There are two types of eye problems that can be corrected with eye laser: myopia (short sightedness), hypermetropia, commonly known as long sightedness, and astigmatism.
For short sightedness to be corrected, it’s necessary to decrease the curvature of the cornea so that it becomes flatter. The tissue of the cornea is then removed, following a disc-shaped pattern. For correcting long sightedness, the central portion of the cornea has to be remodelled by removing tissue in a doughnut-shaped pattern in order to make it steeper. Finally, for astigmatism to be corrected, it’s necessary to re-establish the symmetry of the cornea.
The most common surgical options are PRK and LASIK. In PRK surgery, the pulses of the excimer laser are applied to the surface of the cornea, whereas in LASIK surgery the excimer pulses applied to the cornea under a thin flap of tissue.
The treatments require for an amount of tissue as thin as a hair to be removed; mild eye focusing errors require only the removal of very small tissue amounts. On the other hand, more serious focusing problems will require the removal of a greater amount. All considered, the use of the laser in eye laser treatments normally lasts less than one minute.