A comparison of the accommodative response and contrast in young adults fitted with multifocal and monofocal contact lenses

Abstract: Aim: The aim of this study was to compare the effect of multifocal and monofocal contact lenses in the accommodative response and contrast sensitivity in young emmetropic adults. Method: The requirements to take part in the current study were no ocular pathology, healthy corneas, no refractive surgery and an acuity of at least 1.0 on the Snellen chart with a good binocular vision. Thirteen individuals participated in the study, 9 females and 4 males, with an mean age of 22.6 years (SD=3.4). In separated fittings, participants were fitted with: 1) multifocal lenses, centre-distance design and 0.00D (add +2.00D) (Coopervision Biofinity) and with 2) single vision  +2.00D (Coopervision Biofinity. Refraction was assessed 3 times in both eyes: with each fitting and also without any lens. A Metropsis system (CRS) was used to measure the contrast sensitivity and visual acuity. Results: In this study we found statistically significant differences in accommodative response between the conditions non-lens and multifocal contact lens (p<0.05) and non-lens and monofocal lens (p<0.001). The difference between the multifocal lens and monofocal lens was not statistically significant. The results from the contrast measurement showed an increased contrast thresholds with the multifocal contact lens when compared with non-lens. Conclusion: This study shows that the multifocal lens reduce only partially the accommodative response in young individuals. In addition multifocal contact lenses, fitted in emmetropic participants, reduced contrast sensitivity.