Characterizing power profiles of a concentric ring multifocal contact lens for myopia management: a novel approach

This study presents a systematic method for characterizing power profiles of concentric ring multifocal contact lenses (MFCL), specifically the MiSight® lens used in myopia management, and evaluates the potential of Multivariate Adaptive Regression Spline (MARS) modelling to extrapolate profiles across a full dioptric range. Power profiles of eleven MiSight® lenses (-0.25D, then -1.00D to -10.00D in 1.00D steps) were measured using the NIMOevo® system. MiSight® lenses comprise four concentric zones, with zones 2 and 4 providing additional plus power. Centre thickness (CT) was measured using an immersive spectral-domain Optical Coherence Tomographer. Zonal boundaries were determined as asymptotes of a four-parameter sigmoidal function fitted to junctions between zones, average power within each zone was calculated between these boundaries. MARS was trained on the measured power profiles and used to generate theoretical power profiles for intermediate powers. These were validated against independently measured lenses with matching labelled powers (-1.50D, -3.50D and -6.50D). The proposed method identified consistent zonal boundaries across labelled powers, with minor power-dependent variations. CT correlated significantly with labelled power (r = 0.78). Zone 2 addition powers were consistent, while zone 4 demonstrated a decreasing trend with increasing negative power. The MARS accurately modeled boundary locations and addition powers. This framework offers a systematic approach for analyzing zonal MFCL power profiles, addressing the method for determining zonal boundaries. Additional plus power provided by MiSight® lenses varies across the two zones, with a pronounced effect of reducing addition power in zone 4. MARS modelling allowed extrapolation of power profiles and warrants further investigation.