To describe peripheral defocus when myopic eyes are corrected with spherical and center-distance multifocal soft contact lenses while looking at distance and near.
Twenty-five young adults with spherical contact lens-corrected refractive error of −0.50 to −6.00 D participated. Refractive error of each participant’s right eye was measured while it wore a spherical soft contact lens (Biofinity) and again while it wore a center-distance multifocal soft contact lens with a +2.50-D add (Biofinity Multifocal “D”). Measurements were made centrally and along the horizontal meridian at ±20, ±30, and ±40 degrees from the line of sight at distance and near (3.33-D demand).
The mean (±SD) age and spherical equivalent refractive error were 23.8 ± 1.3 years and −3.62 ± 1.56 D, respectively. At distance, the multifocal contact lens resulted in significantly more myopic defocus than the spherical contact lens at the 40- and 30-degree locations on the nasal retina and at the 20- and 30-degree locations on the temporal retina (p < 0.0001). When accommodating to a near target, peripheral defocus was more myopic with the multifocal lens than with the spherical lens (p < 0.0001). When viewing the near target with the spherical lens, participants experienced foveal hyperopic defocus and peripheral hyperopic defocus at all but one peripheral location. While participants also experienced foveal hyperopic defocus with the multifocal when looking at near, peripheral defocus was minimal (not significantly different than zero) at several locations (i.e., peripheral emmetropia).
The center-distance multifocal lens created peripheral myopic defocus when looking at distance. When looking at near, the multifocal lens resulted in relatively more myopic (less hyperopic) peripheral defocus than the spherical lens. The defocus profiles experienced with the multifocal contact lens in this study make it a good candidate for studies seeking to examine the effect of peripheral myopic defocus on myopia progression in children.
*OD, PhD, FAAO
College of Optometry, University of Houston, Houston, Texas.
David A. Berntsen, University of Houston, College of Optometry, 505 J Davis Armistead Bldg, Houston, TX 77204-2020 e-mail: email@example.com