Current trends of power and spherical aberration profiles in commercial multifocal soft contact lenses

Abstract

Purpose : To evaluate the optical power and spherical aberration (SA) profiles of commercially-available soft multifocal contact lenses (MFCL) across a range of powers and compare their optical designs.

Methods : The power profiles of thirty-eight types of the most commonly prescribed MFCLs from the 4 major commercial CL manufacturers were evaluated. Three lenses each were measured in powers +6 D, +3 D, +1 D, -1 D, -3 D and -6 D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured across 8 mm optic zone diameter in multifocal mode of operation. The amount of SA was calculated between 1.0 and 3.5 mm half chord for all types.

Results : Three classes of power profiles were identified: center-near, center-distance and concentric-zone ring-type designs. Most of the lenses were designed with noticeable amounts of spherical aberration. The lens types were categorized into two distinct groups: lens types where SA was power dependent, usually more negative for higher minus powers and more positive for higher plus powers, which on average varied from -1.91 D to +1.20 D across the power range with slope of 0.258 (95% confidence interval (CI) 0.234 to 0.282), and lens types where SA was consistent across the power range, which on average varied from -1.92 D to -1.60 D across the power range with slope of 0.020 (95% CI 0.003 to 0.038) (see Figure 1).
In terms of generational changes, the relative plus power for PureVision Hi add MF of approximately 2.50 D was reduced to 2.00 D for the PureVision2 lens. The relative plus for the high add Acuvue lenses dropped from 3.00 D for the Acuvue Bifocal to 1.70 D for the ACUVUE® OASYS® for PRESBYOPIA and further to 1.35 D for the 1-DAY ACUVUE® MOIST MF.

Conclusions : Power profiles vary widely between the different lens types, however certain similarities were noticed between some of the center-near designs. For the more recently released lens types, there appears to be a trend emerging to reduce the relative plus with respect to prescription power, to include negative spherical aberration, and to keep the power profiles consistent across the power range.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Average of spherical aberration across six power range for lens types with non-uniform SA and lens types with uniform SA as a function of power. Error bars indicate standard deviations between lens types in each group.