Abstract
To evaluate the impact of multifocal contact lens wear on the image quality metrics across the visual field in the context of eye growth and myopia control. Two-dimensional cross-correlation coefficients were estimated by comparing a reference image against the computed retinal images for every location. Retinal images were simulated based on the measured optical aberrations of the naked eye and a set of multifocal contact lenses (centre-near and centre-distance designs), and images were spatially filtered to match the resolution limit at each eccentricity. Value maps showing the reduction in the quality of the image through each optical condition were obtained by subtracting the optical image quality from the theoretical physiological limits. Results indicate that multifocal contact lenses degrade the image quality independently from their optical design, though this result depends on the type of analysis conducted. Analysis of the image quality across the visual field should not be oversimplified to a single number but split into regional and groups because it provides more insightful information and can avoid misinterpretation of the results. The decay of the image quality caused by the multifocal contacts alone, cannot explain the translation of peripheral defocus towards protection on myopia progression, and a different explanation needs to be found.
Highlights
To evaluate the impact of multifocal contact lens wear on the image quality metrics across the visual field in the context of eye growth and myopia control
The core findings are split into three main groups: (A) the analysis of the root mean square errors (RMSE), where a single number reports the differences against the achievable limit for each image quality conditions, (B) the full-field data-sets analysis, where all the points from the maps were analysed, and (C) the sub-analysis by regions and groups, where points are analysed by taking into account their location and the refractive pattern of the subject
Image quality metrics were computed across a large visual field, for the naked eye but for two different optical designs of multifocal contact lenses
Summary
To evaluate the impact of multifocal contact lens wear on the image quality metrics across the visual field in the context of eye growth and myopia control. Eye growth might be prompted in case a large anisotropy is present in the periphery[25], and the underlying mechanism of multifocal contact lenses may be related to a reduction of the ratio of radial to azimuthal contrast[25] This anisotropic or directional blur has been reported to match neuronally, suggesting a coupling between the two systems[25,26,27,28,29]. This hypothesis can not explain why some contact lenses still report some effect slowing myopia even after two years of wear[7,30] Another hypothesis suggests that the ebb in the image quality might be a possible indicator for the retina to react to the presence of blur, deploying signals that are related to the growth of the eye[30]. Wave-front technologies allow us to recompose refractive errors and aberrations of the eye at different eccentricities[31] and image quality metrics can be computed readily across the visual field
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