Editing Visual system (section)

===Adulthood===

Vision is often one of the first senses affected by aging. A number of changes occur with aging:
* Over time, the [[Lens (anatomy)|lens]] becomes yellowed and may eventually become brown, a condition known as brunescence or [[Brunescent cataract|brunescent]] [[cataract]]. Although many factors contribute to yellowing, lifetime exposure to [[ultraviolet light]] and [[ageing|aging]] are two main causes.
* The lens becomes less flexible, diminishing the ability to accommodate ([[presbyopia]]).
* While a healthy adult pupil typically has a size range of 2–8&nbsp;mm, with age the range gets smaller, trending towards a moderately small diameter.
* On average [[Tears|tear production]] declines with age. However, there are a number of age-related conditions that can cause excessive tearing.