Purpose: Myopia is projected to impact over 50% of the global population by 2050. However, we currently know little of the consequences of myopia on visual brain functions. Theoretical models point to a key role of optical blur in myopia's natural history. Moreover, myopia is linked to long-lasting changes in cortical visual areas. We thus hypothesized that adults suffering from moderate myopia process visual stimuli under optical blur differently than emmetropic adults. Methods: Emmetropes (n=12, males n=3, females n=9) and low to mild myopes (n=13, males n=4, females n=9) were tested in the condition of -3 diopters of lens-induced blur. Participants performed an illusory contour recognition task while high-density EEG was recorded and analyzed using an electrical neuroimaging framework. Results: We provide evidence for cortical processing differences between emmetropes and mild myopes - both of whom were tested under -3D of defocus. From topographic modulations it followed that emmetropes and mild myopes engage (partially) distinct networks of brain regions. Source estimations localized these differences to the medial portion of the occipital pole. Moreover, the predominant topography of the VEP during this period not only correlated with SRE, but also was an excellent classifier of myopia vs. emmetropia. By contrast, our analyses provided no evidence for differences in visual completion processes. Conclusions: To our knowledge, this is the first study of myopia pairing high density EEG and a behavioral task. Collectively, this pattern of findings supports a model of myopia wherein low-level visual cortices are impacted at relatively late post-stimulus processing stages.

The authors have declared no competing interest.

KS is supported by an MD-PhD fellowship of the Swiss Academy of Medical Sciences (Grant MD-PhD 21/21). MMM is supported by the Swiss National Science Foundation (Grant 169206).

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The Cantonal Ethics Committee of the Canton of Vaud in Switzerland gave ethical approval for this work (protocol #2018-00240). All participants provided written informed consent after verbal and written explanation of the study, according to the tenets of the Declaration of Helsinki.

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