Normal vision

Light rays pass through the cornea and focus on the retina. Both distant and close vision are clear.

Myopia

The eyeball is too long.
Light rays focus in front of the retina.
Distant vision is blurry.

Hypermetropia

The eyeballis too short.
Light rays focus behind the retina.
Close vision is blurry.

Astigmatism

The curve of the cornea is irregular.
Light rays focus at multiple points.
Both distant and close vision are blurry.