Scleral lenses part 2 – indications

Contact lenses constructed in rigid gas permeable (RGP) materials are classified by their predominant bearing surface. Those that rest their weight on the cornea are known as corneal RGP contact lenses (corneal for short) while those that are sufficiently large and fit in such a way that the lens bears on both the conjunctiva and cornea are termed corneo-scleral RGP contact lenses (corneo-scleral for short). Lenses that vault the cornea and rest on the conjunctiva are known as scleral RGP contact lenses (scleral for short) and it is these lenses which are the focus of this series of articles.

While scleral lenses are generally larger than corneo-sclerals, which in turn are generally larger than corneal lenses, a fixation on lens size can cause confusion. A lens which is 14.8mm in diameter for example may be sufficiently large to be fitted ‘as a scleral’ and therefore vault a small cornea, while a similar 14.8mm lens may barely reach the limbus when placed on a larger cornea.