Sea, snow, high mountains… in summer our eyes are more exposed to the sun. The light that reaches and penetrates the human eye is divided into visible spectrum (between 380 nm and 780 nm) and non-visible spectrum (which includes ultraviolet rays and infrared rays).
Ultraviolet (UV) rays are very harmful as they are absorbed by the cornea and lens of adult individuals, while blue light (between the visible spectrum and UV rays) penetrates the lens damaging the retina.
Why is it important to protect your eyes? How can we safely expose to the sun? What features must sunglasses have? In this interview Dr. Francesco Loperfido, Head of the General Ophthalmology Service of the IRCCS San Raffaele Hospital, answers.
During summer the eyes are exposed to excessive contact (direct or indirect) with UV rays. This exposure, more frequent to the sea, on the snow or in the high mountains, can determine an actinic conjunctivitis, painful keratitis and photophobia: it is therefore necessary to protect the eyes adequately.
In particular, attention must be paid to two categories:
A general rule valid for all is to adapt the protection of our eyes in relation to your holiday place: the amount of UV rays is different depending on whether we are in the city, at the beach or in the mountains, and the quality of protection must therefore be different.
In very high mountains, for example, you need to choose glasses with mirrored lenses that shield you from UV rays but also blue light that reaches the peaks, and that adapt efficiently to climatic changes. If we go to very windy places we might prefer a curved eyewear. At sea instead it is better to choose a polarized lens, which removes water reflections; an interview with the optician will allow customizing the glasses according to our needs.
It is also very important to identify the type of lens based on a possible visual defect: sometimes, green lenses can cause nausea in subjects with strong myopia, while brown lenses can cause nausea in very hypermetropic subjects. Elderly might find useful the photochromic or intelligent lenses, which change their color from completely transparent when we are indoors to partially colored in cars (most of the UV rays are absorbed by the windshield of the car) to very dark when outdoors.
Yes, they do; light eyes must be protected more carefully because they have less pigment at the level of the iris and retina, two epithelia that contribute to defend our eyes.
There is no “perfect sunglasses”, but it is possible to identify some characteristics that make it optimal:
Few but important points: