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Simon Winter, Linda Lundstrom, Mohammad Taghi Fathi, Abinaya Priya Venkataraman, Anne Seidemann, Peter Unsbo; Horizontally induced transverse chromatic aberration reduces peripheral acuity. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2115.
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The effect of spectacle-induced transverse chromatic aberration (TCA) on peripheral vision is rather unknown despite the fact that all spectacles induce TCA in the periphery. The aim of this study is to evaluate how TCA affects visual acuity and to see if the natural TCA of the eye can be corrected.
TCA was induced by trial lenses with varying prismatic power. These lenses were aligned horizontally from 9.5 Δ base in (BI) to 9.5 Δ base out (BO). Visual acuity was studied monocularly in the fovea (resolution acuity) and in 20° nasal visual field (detection acuity) of the right eye. Four subjects were measured in three repetitions. A Bayesian two-alternative-forced-choice method using oblique high contrast Gabor gratings was applied. During all measurements, monochromatic aberrations were corrected by an adaptive optics system [Rosén et al., J. Mod. Opt., 2012] running in continuous closed loop. The data of all three measurement series for each subject were pooled, and a least square fit of a v-shaped function performed.
The average sensitivity to TCA in the periphery was calculated to (0.020±0.004) logMAR/Δ for BI, and (0.013±0.005) logMAR/Δ for BO (an example of one subject is shown in Fig. 1). The foveal sensitivity was (0.011±0.002) logMAR/Δ for BI, (0.010±0.005) logMAR/Δ for BO. The induced TCA that gave best peripheral acuity was shifted BO compared to the fovea. This shift is according to theory; the natural TCA of the eye in 20° nasal visual field corresponds to the one of a BI-aligned prism.
The results indicate that peripheral vision is more sensitive to TCA than foveal vision. Furthermore, the presented protocol may be utilized as an indirect method to measure the natural TCA of the peripheral eye.
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