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Eric Seemiller, T. Rowan Candy; Interocular correlation between human retinal images at six-weeks of age. Journal of Vision 2013;13(15):P27. doi: 10.1167/13.15.62.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: The developing visual system must make an appropriate vergence movement to fixate a target and permit binocular function. The visual system must plan vergence responses based on retinal images complicated by external factors (e.g. variable scene content) and developmental hurdles (e.g. immature ocular optics). Our goal was to determine the uniqueness of vergence solutions given variation in both scene structure and the optics of the developing eye.
Methods: We used an interocular correlation (IOC) algorithm sampling from right and left stereo image pairs. Natural images were filtered with infant optics (i.e., higher order monochromatic aberrations, hyperopia and anisometropia) to simulate retinal images, and the IOCs were determined.
Results: Two metrics were used to quantify the IOC across absolute disparity offset; both were variable across scene type and dependent on the relative disparity in the image. The correlations became more homogenous as defocus increased in the filtered image, indicating that unique solutions became less prominent as hyperopic defocus increased. Furthermore, we found that 2D and 4D of anisometropia decreased the prominence of a unique solution more than equivalent amounts of bilateral defocus (2D: t=3.6, p=0.002; 4D: t=2.8 p=0.011 ) suggesting the information available for vergence may be more reliable with bilateral hyperopia than with anisometropia.
Conclusions: As expected, IOCs become less reliable when high spatial frequencies are removed with increasing defocus. More interestingly, we found that anisometropia increased this effect beyond that of bilateral defocus. Physiological or behavioral data are required to test these findings in infancy.
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