The Sun is constantly emitting radiation in the most pernicious spectra so the first reason is to protect your eyes from ultraviolet rays. Everybody must remind that UV radiation could be augmenting due to recent changes in the atmospheric protection, and it's believed to be a consequence of ozone depletion and other pollution forms.
UV radiation is very dangerous toward several organic tissues, so anyone should take care of avoiding exposure specially when the purpose is to live healthy at all ages.
Another reason appears in glare protection. A factor that decreases risks in several situations, singularly driving. Sometimes to see clearly could be a decisive factor and some sunglasses also bundle polarized lens.
It's relevant to buy quality sunglasses because cheap ones use normally plastics that degrade visual perception and could fail in filtering harmful radiation. Anyway, they protect from glare and excessive luminosity as well.
As the eye tries to adapt itself to different situations, it's possible to conceive a plan for achieving a specific performance in dark or bright environments thanks to sunglasses.
To finish the article, let us add that some sunglasses add a touch of style!