ELI5: Explain Like I'm 5

Refractive error

Refractive error is when the shape of your eye is not quite right, and that makes it harder for light to travel through your eye and reach the back of your eye. That makes it hard to see things clearly. To fix this problem, you might need to wear glasses or special contact lenses that help the light travel through your eye and reach your retina, so that you can see clearly.