The process that we know as “vision” involves multiple, complex functions and numerous anatomical structures along the visual pathway. A disruption to any of these functions – from the movement of the eye muscles to the focusing of light into the eyeball to the transmission of the visual signal through the brain to interpretation of this signal – can result in various problems, including headaches, double vision, failure to process the visual signals meaningfully, loss of areas of the visual field, and of course, blurry vision.

For the majority of humans, blurry vision arises from problems at a specific step in the visual pathway – the refraction and focusing of light through the eyeball. This leads to what we call “refractive error.”
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