Plastic modification of the cornea by pneumatic force corrects myopia: Pneumatic keratology

PurposeThe eyeball and, in particular, the cornea deform in vitro by the application of a distending force like other visco-elastic tissue. If the force is large enough, the cornea strains beyond the elastic range, and a permanent deformation occurs. Such permanent strain is referred to as 'plastic' strain. The phenomenon, however, has never been observed or produced on living tissue. This report seeks to demonstrate that the central radius of a patient's cornea can be altered in a controlled manner designed to correct refractive errors.MethodsTo plastically deform the living cornea, we applied a vacuum to the cornea of eight rabbits and five human eyes with a novel device. This device consists of a chamber of 11 mm in diameter. The chamber is radially divided into four interconnected sub-chambers.ResultsHere we show that a strain can be achieved in vivo with a force produced by the application of the specially designed chamber where air is evacuated. An anatomical modification of the cornea of humans and rabbits was achieved. The deformation of the cornea was plastic, and therefore permanent.ConclusionsThe method described here-Pneumatic Keratology- can be used to alter the cornea by non-invasive means. A vacuum chamber with radial openings alters the collagen fibers in the stroma and flattens the cornea. A flatter cornea corrects or reduces myopia.