It consists of a plane from which a sharp blade emerges on an angle of ± 26°. The blade is driven by a foot pedal-controlled motor that provides an oscillatory motion. The guide on both sides of the plane contains a groove on the outside edge for snug fitting of the fixation ring.

The separation between the anterior plane and the edge of the cutting blade corresponds to the thickness of the tissue to be cut. The resection diameter is determined by the height of the pneumatic fixation ring.

Ancillary instruments: pneumatic fixation rings, pre-surgical tonometer, applanation lenses, calipers for corneal flap thickness calibration, artificial chamber.

Instrument sizes were carefully studied in relation to the globe, the most frequent corneal curvatures, the size of the palpebral fissure and the mechanical needs.

The shape of the disc cut with the microkeratome is that of a hollow sphere cap with beveled edges. The slope of the bevel varies with the size of the resected disc depending either on the more oblique incidence of the blade on the corneal surface in cases of smaller diameter corneas (A), and more perpendicular in corneas with larger diameters (B). This unique characteristic allows to obtain positive lenticles and resections used in diameters of less than 6.5 mm.

The microkeratome must be used in uniform-thickness corneas since it resects a parallel-face disc following the anterior surface of the cornea. When used on a cornea of irregular thickness, the remaining bed is irregular or will open into the anterior chamber, even if the disc is uniform.

The microkeratome has evolved to the point that several models exist at present and they are now available with linear translation, rotary pivotal and pendular motions.