[Bifocal contact lenses as a correction method in presbyopia]

A study aimed at assessing the efficiency of presbyopia correction by bifocal contact lenses (BCL) was undertaken; it envisaged a comprehensive evaluation of subjective data provided by patients and measurements of a number of functional parameters of the visual quality for far and near, including mono- and binocular measurements with BCL of different constructions versus a maximal sphero-cylindrical spectacle correction for far and for near. Soft Acuvue Bifocal BCL as well as soft and rigid BCL manufactured in the optical-and-mechanical laboratory of the Research Institute for Eye Disease of the Russian Academy of Medical Sciences and Russian-made and imported bifocal soft and rigid lenses, respectively, were made use of in the study. A reduced contrast sensitivity (mainly in high frequencies) to 7% with Russian-made BCL, to 12.5% with Acuvue Bifocal BCL, to 8.7% with monofocal BCL and to 13.4% with the "mono-vision" system was registered. A decreased visual working ability to 13% with soft bifocal Russian-made BCL, to 17.3% with Acuvue Bifocal BCL and to 20.7% with the "mono-vision" system was detected versus the spectacle correction. A reduction by 25% was noted in the stereoscopic vision indices with the "mono-vision" system. A study of sensitivity to dazzling did not show any statistically reliable differences between various correction types.