Current trends in modern orthokeratology

The present article describes the basic concepts and principles of modern orthokeratology. Early investigators postulated a variety of theories. However, controlled clinical studies have shown these methods to be both unpredictable and also modest in their ability to correct myopia. These traditional techniques involved fitting lenses according to a `rule-of-thumb' and clinicians had no means of accurately evaluating corneal topography. More recently, with the significant advances in corneal topography systems and the application of reverse geometry lenses (lenses where the secondary curve steepens) certain investigators have concluded that the technique can rapidly reduce greater levels of myopia with greater predictability. The procedure involves a more scientific sagitta based fitting philosophy and predictability is defined according to corneal asphericity.