Accommodation refers to the way our eyes increase optical clarity by changing the shape of the lens. The result is clear, focused, images of the world regardless of whether we are looking at things close by or in the distance.

About accomodation
  • Our eyes focus on different things by changing the shape of the lens through accommodation. This is controlled by ciliary muscles.
  • The distance of objects of interest to an observer varies from infinity to next to nothing but the image distance remains constant.
  • The image distance is measured between the retina (the detector) and the cornea (the refractor) and is fixed in the human eyeball.
  • Because the image distance is fixed, our eyes accommodate by using the ciliary muscles to alter the focal length of the lenses in order to focus images of both nearby and far away objects on the retinal surface.
  • The ability of our eyes to adjust focal length is known as accommodation.
  • Our eyes accommodate by forming a lens shape that has a shorter focal length for nearby objects. In this case the ciliary muscles squeeze the lens into a more convex shape.
  • For distant objects, the ciliary muscles relax, and the lens adopts a flatter form with a longer focal length.