Abstract
A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.