Keratomileusis is a type of elective vision correction surgery. It is performed with the goal of enabling the patient to stop wearing glasses or contacts. The process consists of cutting the cornea at the front of the eye into a flap so that it can be lifted, trimming and reshaping the tissue in order to correct the vision impairment, and then replacing the flap and securing it with sutures. The procedure can be completed manually or, more commonly, with the use of lasers in a process known as laser-assisted in-situ keratomileusis (LASIK). It can be used to correct astigmatism, farsightedness, and nearsightedness.
The primary goal of keratomileusis is to improve vision by adjusting light refraction through the cornea. This typically involves changing the shape of the cornea so that it is configured for optimum processing of light before it reaches the retina. Before the cornea can be reshaped, a portion must be removed, either via freezing and manual removal or a laser.
A surgical instrument called a microkeratome is usually used to cut the flap in the cornea. The blade of the tool works by moving in a swinging motion. It has often been used in combination with a laser to perform vision correction surgery. The cut in the cornea may also be made with a delicate femtosecond laser, which is a newer surgical tool.
When keratomileusis is performed as a part of the LASIK procedure, the microkeratome or femtosecond laser are typically used with an excimer laser. This tool reshapes the corneal tissue once the top flap has been made. It is particularly suited to eye surgery because it is capable of delicate precision work, in addition to leaving the remaining surface cool after removing tissue from the eye.
Before the use of lasers became widespread, the cornea was usually trimmed manually. The portions of cornea to be removed were frozen by a tool called a cryolathe and cut into the desired shape. When the frozen areas thawed, the reshaped flaps were put back into place beneath the outer eye flap.
Keratomileusis was developed by Spanish ophthalmologist José Ignacio Barraquer Moner, a surgeon who was responsible for many of the key advancements in modern eye surgery. Moner also developed keratophakia, a procedure in which corneal tissue from a donor is transplanted into a patient’s eye. He invented the microkeratome and cryolathe as well, so that he could properly perform his own procedures.