Cornea-contact lens interaction in the aquatic environment.

A large population of ametropic scuba divers wear contact lenses. We discuss optics and corneal physiology, as well as the types of contact lenses that are appropriate for underwater activities.We reviewed an extensive body of literature to formulate guidelines to aid the contact lens fitter in satisfying individual sport diver's needs.Optical factors such as image displacement and light wave-length shifts require that contact lenses for underwater use be suitably modified. Underwater images appear nearer and larger (requiring greater accommodation) and are made up almost exclusively of the short wavelength end of the spectrum. Correction of presbyopia, in particular, is influenced by these factors. For example, presbyopic contact lens-corrected myopes require greater near adds underwater than when viewing the same objects in air. In general, presbyopes should consider monovision correction to facilitate underwater visual tasks. Although divers wearing rigid gas permeable contact lenses run the risk of more corneal problems than soft lens wearers if conservative ascents are not adhered to, there are no compelling reasons to change lens types in patients who are already fully adapted. Soft contacts, while very stable on the eye during diving, present a greater risk of lens contamination by sea or fresh water exposure. However, the latter problems are easily overcome by using disposable soft lenses.In this paper, we present several suggestions for lens material, modifications required for underwater ametropia correction, and wearing modalities for the sport divers. An understanding of the dramatic changes that impact the properties of light, corneal physiology, and visual perception which accompany the diver below the surface will enable the contact lens fitter to design a lens appropriate to the needs of the individual patient.