Thornton Guide for Radial Keratotomy Incisions and Optical Zone Size

The Thornton Guide is designed to provide a predictable correction of myopia and astigmatism without overcorrection by following a specific set of guidelines based on 98% depth at the optical zone margin with eight or more incisions. The object of the guide is to provide maximum correction with the largest possible optical zone. The rationale for the number of incisions and how to apply various modifiers such as age, sex, corneal curvature, and intraocular pressure are explained.