There seems to be an exact point where you lose focus on an item when bringing it closer to your face. The closer it gets, the blurrier it gets – even with only one eye open. Why is this?
In: Biology
I wished you had not have asked it within this thread, because my whole being wants to say because of genetics and evolution, but this thread requires me to explain myself thoughtfully and more fully than simple words. The explanation is that this happens due to chemicals and traits passed down genetically from ancestors that depended on movement receptors in order to survive.
Your eye lens has to adjust shape in order to change focus. It would have to adjust to infinite curvature in order for it to focus on something touching the front of your eye. For things super close to your eye, it has to adjust to extremely high curvatures and eventually can’t go any further.
To maintain focus the eye has muscles that pull on a clear piece of tissue that is the lens in your eye, changing its shape. At some point those muscles and the ability of that tissue to be deformed reaches its limit.
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