Compensation for axial elongation during multifocal soft contact lens wear: Results from the BLINK study.

PURPOSE: To determine the effect of +2.50 D add multifocal soft contact lenses (MFSCLs) compared to +1.50 D add and single vision contact lenses (SVCLs) on the relationship between axial elongation and myopia progression.

METHODS

Individual estimates of D/mm were derived from the CLEERE Study, then applied to data from 289 participants in the BLINK Study to determine the portion of axial elongation that either contributed (uncompensated elongation) or did not contribute to myopia progression (compensated elongation). BLINK participants had myopia between -0.75 D and -5.00 D and were 7-11 years of age when enrolled in a 3-year clinical trial of multifocal contact lens myopia control. Cycloplegic refractive error was measured under tropicamide cycloplegia with the Grand Seiko WAM-5500 Binocular Autorefractor/Keratometer and axial length was measured using the Lenstar LS 900.

RESULTS

The majority of the inhibition of axial elongation during myopia control with +2.50 D add MFSCLs was inhibition of uncompensated elongation. Over 3 years, axial elongation was less in +2.50 D add MFSCLs (0.39 mm) compared to SVCLs (0.62 mm) by 0.23 mm (95% CI: 0.14, 0.33), split between 0.17 mm (95% CI: 0.091, 0.26) of uncompensated elongation and 0.055 mm (95% CI: 0.013, 0.097) of compensated elongation. Inhibition of compensated elongation only occurred in the first year of the study. Total axial elongation over 3 years would need to be reduced to 0.17 mm (0.45 mm less than 0.62 mm) to result in no myopia progression.

CONCLUSIONS

Optical myopia control with multifocal contact lenses has a small but significant effect on the compensation for elongation from changes in the optical components of the eye. As a result, myopia control must set an aggressive therapeutic target if the goal is slowing axial elongation to the point of no net myopia progression.