The challenge of fitting astigmatic eyes: rigid gas-permeable toric lenses

It is generally acknowledged that rigid gas permeable lenses (RGP) afford superior visual correction of the ametropic eye compared with hydrophilic lenses. However, there are occasions when a spherical rigid lens will not provide an acceptable result in terms of fitting or vision on astigmatic eyes. In these instances a toric RGP lens will be required. This paper deals with the definitions, indications, fitting technique, calculations and designs relating to this modality of fitting. Whilst often perceived as a complex area within contact lens practice, the basic optics and fitting of toric RGP lenses is not overly difficult. A simple empirical means of fitting the lenses will be described which has a high 'First-fi' success rate.