Far sighted

  Near sighted

  Astigmatism

Light rays focus behind the retina (back of the eye like the film in a camera)

Light rays focus in front of the retina

Some light rays focus in front of the retina and some behind.

  REMEDY

The eye can focus the lens to remedy small and equal amounts

Near objects can be seen well, all distance objects are blurred. Squinting helps distance vision some.

The blur is always present.

  TREATMENT

plus lens

minus lens

cylinder lens