Am I understanding this right? The choroid layer behind the retina gets slightly thinner when we look at dark details on a bright background, and slightly thicker when we look at bright details on a dark background, and somehow this causes an opposite effect in the overall eye growth over time. So spending a lot of time looking at dark letters on a bright background would cause the eye to become too long and unable to focus on objects far away.
Is there an explanation for why the choroid changes its thickness, and why this change would create an opposite effect in eye growth over a longer period?