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.
Highlights
Numerous studies have investigated the potential use of multifocal contact lenses in controlling myopia progression [1,2,3,4,5,6,7,8,9,10]
With-lens peripheral mean refraction between GS and COAS were irregular for most participants (Fig. 8, column 2) and these differences beyond 25° were greater in the nasal field than in the temporal field
Three participants showed slightly more negative peripheral refraction with the GS compared with the COAS for most temporal field angles, but participants 1 and 2 showed the opposite
Summary
Numerous studies have investigated the potential use of multifocal contact lenses in controlling myopia progression [1,2,3,4,5,6,7,8,9,10]. The Grand-Seiko WAM 5500 auto-refractor/keratometer measures through an annulus of 1.5 mm inner and 2.3 mm outer diameters [15], and Hartmann Shack aberrometers capture data across the whole pupil from which the user can select the diameter of the region of analysis and the method to quantify the refraction [16]. We hypothesize these method-dependent factors affect what refractive state is reported and its interpretation on myopia control
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