[Applanation tonometry on contact lenses with high water content. Problems, results, correction factors]

The use of contact lenses with high water content for different therapeutic purposes has become widespread in the past four years. Permanent-wear contact lenses of this type are used in the treatment of corneal conditions which resist therapy, and also postoperatively. They cause no problems in follow-up examinations with the slit lamp but make it very difficult to measure IOP, which is frequently necessary in such cases. Therefore, we carried out invetigations with the aim of calculating correction factors for applanation tonometry on contact lenses with high water content. It was found that the power of the contact lens has a highly significant effect on the reading obtained. Simple correction tables are given which enable a sufficient degree of accuracy to be achieved in tonometry on these contact lenses.