It occurs because light entering the eye is focused in front of the retina instead of on it.
(It; occurs; because light entering the eye is focused in front of the retina instead of on it) (light; entering; the eye) (light entering the eye; is focused; in front of the retina)
It light light entering the eye
occurs entering is focused
because light entering the eye is focused in front of the retina instead of on it
the eye
in front of the retina