Computer modeling of wound gape following radial keratotomy.

BACKGROUND

The edges of radial keratotomy incisions remain separated by epithelium or new collagen. To determine if the amount of gape of the incision edges agrees with the induced corneal flattening, two mathematical models of the cornea were studied.

METHODS

A finite element model of the eye was constructed; radial incisions through Bowman's membrane and stroma were simulated, as well as incisions confined to the stroma but not involving Bowman's or Descemet's membranes. Geometrical calculations were also performed in a second morphologic model of a spherical shell.

RESULTS

The finite element and geometrical models agree closely on the corneal curvature change for a given incision gape. Both models predict that linear intrastromal incisions that do not involve Bowman's layer would not produce significant corneal flattening.

CONCLUSIONS

Corneal flattening after radial keratotomy is closely related to incision gape, mediated through structural weakening of the cornea. Purely intrastromal radial incisions, as might be created with Nd:YAG lasers, prevent wound gape and would not appear to be a promising technique for flattening the cornea.