The process by which certain muscles (called ciliary muscles) function, to change the focal length of the eyes so that the image is clearly formed on the retina is called the accommodation of the eye.
It is the process where the relaxation of zonular fibers enables the lens to become more globular, hence increasing its refractive power.
With the relaxation of the ciliary muscles, the zonular fibers become taut flattening the lens, and reducing the refractive power.
This is linked with the constriction of the pupil and enhanced depth of the focus.
This will vary for near and distant objects and also for objects moving away or towards the eye.
It is a reflex that is initiated by visual blurring or/and awareness of the proximity of the object of interest.
The majority of accommodation depends on the contractility, of the ciliary muscle and the rigidity of the lens.
With aging, as the lens gets more rigid, accommodation declines.
