Ocular aberrations and visual function with multifocal versus single vision soft contact lenses

PurposeTo investigate differences in ocular aberrations induced by centre-near multifocal soft contact lenses (SCL) relative to single vision SCLs and their effect on contrast sensitivity function (CSF).MethodsOcular aberrometry was measured in 18 cyclopleged subjects (19–24 years) while wearing Ciba Air Optix low (AOlow) and high (AOhigh) add, Bausch & Lomb PureVision low (PVlow) and high (PVhigh) add multifocals, and a Bausch & Lomb PureVision single vision (PVsv) control with the same −3.00 D distance back vertex power. Zernike polynomials were scaled to 4, 5 and 6 mm pupils. CSF was measured at equivalent distances of 6 m, 1 m and 40 cm while fully corrected with spherical trial lenses at 6 m.ResultsAOlow, AOhigh and PVhigh induced a negative shift in primary spherical aberration (Z12) from PVsv and all multifocal SCLs induced a positive shift in secondary spherical aberration (Z24) (all p < 0.01), without significantly increasing coma. Area under the CSF (AUCSF) reduced at 40 cm for all multifocals relative to PVsv (p < 0.05), but was not significantly different at 6 m or 1 m. A moderate correlation (r = −0.80, p < 0.005) was found between changes in Z12 and AUCSF at 40 cm for AOhigh, with an increase in negative Z12 reducing multifocal-induced loss of CSF.ConclusionsCentre-near multifocal SCLs induced a negative shift in Z12 and a positive shift in Z24. Although CSF was unaffected at 6 m and 1 m it was reduced at 40 cm, possibly because changes in Z12 and Z24 were not great enough to induce a significant shift in centre of focus and increase in depth of field.