Editing Progressive lens (section)

== Adaptation ==
For those new to progressive lenses, an accommodation period is often required because the brain needs to learn to adapt to them.<ref name=Aves>Aves O. (1908) Improvements in and relating to Multifocal lenses and the like, and the method of Grinding Same. GB Patent 15,735.</ref> This period varies from a few hours for some individuals up to around two weeks.<ref>Progressive Addition Lenses: History, Design, Wearer Satisfaction and Trends Pope, D R OSA TOPS Vol. 35, Vision Science and Its Applications, 2000</ref> During this period, side effects can include headache and dizziness. It is advised that, when these symptoms set in, the progressive lenses be removed for a short period and replaced after symptoms have subsided. Returning to an older prescription or different type of lens design (bifocal, trifocal) only serves to increase the adaptation period to the progressive lenses.  Some wearers find the visual discomfort caused by these distortions outweigh the benefits of wearing PALs; this is known as progressive non-tolerance. However, manufacturers claim acceptance rates of 90%–98%.

[[Depth perception]] and distance estimation can be influenced during the adaptation period.