What is a Microkeratome?

A microkeratome is a hand-held surgical implement containing an oscillating blade. It is used to create the corneal flap at the start of a LASIK eye surgery. Originally it was devised by the man who is now known as the "father of modern refractive surgery" -- Jose Barraquer. He was a Spanish ophthalmologist who moved to Colombia in the 1950s and worked on how the eye focuses and how it could be made to focus more accurately.

Barraquer invented the vision correction surgery that developed into LASIK. He called it Keratomileusis. LASIK stands for Laser Assisted in situ Keratomileusis. In Keratomileusis, Barraquer cut off a thin layer from the corneal surface, froze it, reshaped it with a lath, and then stitched it back in place. This changed how the cornea focused light.

The Early Microkeratome

To cut the corneal surface, Barraquer developed the microkeratome, although not exactly in the form that is used today. A few years later he worked with one of his many proteges to automate the microkeratome. This enabled them to make a corneal flap without entirely removing any tissue and freezing it. In other words, they worked on the cornea in situ -- in place on the eye, rather than on a removed part of it. You could say this was "in situ Keratomileusis" -- the "Laser Assisted" part came later.

How a Microkeratome Works

A microkeratome has a motor, gears (most models), and a disposable blade housing. Before it is used, a suction ring is placed on the eye to ensure even and close contact with the microkeratome blade. There is a built-in groove for the blade to slide along as it oscillates to make the corneal flap. The blade is very tiny and precise and along with its housing, should be replaced each time the microkeratome is used. This ensures sterility and sharpness.

As the blade moves across the cornea, there is a part called a plaque that slightly compresses the cornea a little ahead of the blade. This determines how thick the corneal flap will be. Typically the flap will be between 100 and 200 micrometers thick and on average, the human cornea is between 500 and 600 micrometers thick.

Corneal Thickness

Some people have thinner corneas than average. They are not good candidates for LASIK because after the corneal flap is cut, there still needs to be enough corneal thickness to maintain the eye's shape. To offer laser vision correction to these people, other procedures have been developed, one of which is IntraLase. It uses a laser to make the corneal flap instead of a microkeratome. This enables a thinner flap and one that is more microscopically uniform in thickness. You can read more at IntraLase vs. Microkeratome

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