Choosing sunglasses: the filter matters more than the tint
The ultraviolet filter matters more than how dark the lens is.
Sunglass frames are made of plastic or metal, or a combination of the two, and the choice of frame is a matter of personal taste. The lenses are not.
Whatever the frame, the lenses must filter the sun’s ultraviolet rays — and the filter is not the only factor. If the frame is small, ultraviolet light reaches the eye around it. Wide frames matter for that reason.
What a good pair should do
It must contain an ultraviolet filter. The lenses should be optically clear, without reducing acuity or contrast and without causing glare.
They should not be too dark, since heavily tinted lenses reduce vision while driving and create a hazard of their own. Tinted lenses must not distort the perception of red and green — traffic lights depend on it.
The frame should hold the lenses firmly, be robust and not break easily, and have no sharp corners that could injure the eye. It should not be small: a wide frame that covers the eyes from the sides as well is what actually shields them.
The point about cheap lenses
Sunglass lenses may be tinted with a purely cosmetic dye and contain no ultraviolet filter at all — so the darkness of a lens says nothing about the protection it gives.
It is a good reason to buy from manufacturers whose specifications can be relied on.
What they protect against
Comfort against glare is the obvious benefit — the brightness that makes you squint or close one eye.
The less obvious benefit is protection from radiation. Ultraviolet damages the skin of the eyelids, which is thinner than skin elsewhere and needs more protection, and excessive sun exposure causes photokeratoconjunctivitis — watering and light sensitivity severe enough to keep the eyes shut, which settles with treatment in six to twelve hours.
Ultraviolet is also linked to pterygium — the fleshy growth across the eye — to pinguecula, the yellowish raised spots on the white of the eye, to the yellow corneal deposits of Labrador keratopathy, and to cataract.
Have your eyes assessed
Send your prescription history, previous eye reports and any corneal imaging for an individual assessment — in person in İstanbul or over video.
This article is for general information only and does not replace a medical examination or personalised medical advice.