Peripheral Defocus with Spherical and Multifocal Soft Contact Lenses

Abstract

Purpose To describe peripheral defocus when myopic eyes are corrected with spherical and center-distance multifocal soft contact lenses while looking at distance and near. Methods 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° from the line of sight at distance and near (3.33-D demand). Results 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° locations on the nasal retina and at the 20° and 30° 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). Conclusions 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.

Spherical Soft Contact Lens Designs and Peripheral Defocus in Myopic Eyes

“…Both of these optical treatments can induce a peripheral myopic shift in retinal defocus on multiple areas of the peripheral retina. 30, 31 A reduction in axial eye growth ranging from 36 to 55 percent has been reported with orthokeratology treated eyes over a period of two years. 32–35 The effect of bifocal soft contact lenses for myopia control is more varied, ranging from 25% to over 70% reduction in myopia progression, with some of these studies only reporting results over a one-year period.…”

Centration and Decentration of Contact Lenses during Peripheral Gaze

“…However, investigations of peripheral defocus created by soft multifocal contact lenses show little myopic blur on the nasal retina and variable results in the temporal retina. 18–21 Our investigation indicates that contact lenses tend to lag in peripheral gaze, which may underestimate the peripheral defocus associated with soft multifocal contact lens wear. Investigators should have subjects turn their heads to peripheral targets, maintaining primary gaze, and therefore reduce the effects of contact lenses that lagged on peripheral defocus.…”

“…However, there is controversy regarding the amount of peripheral myopic defocus created by soft multifocal contact lenses. 18–21 …”

“…Most studies measuring peripheral defocus at 20 and 30 degrees with a center-distance soft multifocal contact lens found more absolute and relative myopic blur in the periphery, at least in the temporal retina, 18–20 although one found essentially no relative defocus temporally. 21 Nasally, all studies found little relative or absolute blur in the nasal periphery, ranging from +0.60 to −1.25.…”

“…21 Nasally, all studies found little relative or absolute blur in the nasal periphery, ranging from +0.60 to −1.25. 18–21 …”