Our Friend the Sun

by Federico Bartolomei

It is necessary to protect the eyes against the damaging effects of the sun even during winter.


The sun is the main source of energy for all living beings, and an influence on mood and well-being. However, sun tanning has not always had a positive value in history: in ancient Rome, in the 8th century up to the beginning of the 9th century, to be tanned was synonymous with poverty and humble work. When well-being became linked to the ritual of vacation, a lovely tan became associated with healthiness, care and fashion.
In the past decades, also because of important climate change, the sun's action has changed and we often tend to underestimate its risks.
The campaign
"Our Friend the Sun" promoted by the Istituto Cavazza in collaboration with community pharmacies AFM, Ascom, Sindacato Ottici, Istituto di Ottica Benigno Zaccagnini, took place in Bologna in the month of June to create awareness among the population on the importance of protecting ourselves against ultraviolet rays. At a stand organized in Bologna's Piazza Maggiore, health professionals distributed information flyers and gave advice to citizens. With the help of special equipment, passersby received a free examination of their sunglasses to verify their suitability. There was also analysis of people's skin phototype in order to obtain more information about the right choice of sunscreen that should be used.
But why are sun rays harmful?
The light that reaches the earth is composed of particles of variable energy called photons which have various wave lengths
(the unit measure is the nanometer). The shorter is the wave, the higher is the energy and, consequently, greater is the penetration strength and higher is the risk of lesions.
The most damaging rays are the UVC, which are almost all stopped by the ozone layer around the earth, the UVB and the UVA. In the visible component of the light spectrum, which interacts with our eyes' photoreceptors and allow us to see, let us not underestimate the presence of the violet-blue rays which, in values between 380 and 480 nanometers, can result in damaging action and eye problems.

Beyond the 700 nanometers, there are also infrared rays invisible to the eye but perceptible because of the heat they provide. These rays in moderate quantities do not represent risks.
The subject of sun protection is current even in winter, though the radiation dose varies according to the location we are in
, as well as the altitude, longitude and the time of day we are out. UV rays increase by 4% in intervals of height of 300 meters and the snow reflects up to 80% of the UV rays. Clouds filter only 10% of ultraviolet rays, and that is what reaches us when we stay in the shade, but since it is not possible to stay in the shade during the skiing season, we need to protect our eyes from the damaging effects of the sun.
There are in stores many different types of glasses; each has their own characteristics relative to the lens and frame. How to choose the right sunglasses?
It is important to know that there are four categories of protection:
Category 0
- 1 (transparent filter, very clear): for closed spaces and days with little light.
Category 2 (medium filter): for medium light and cloudy days.
Category 3 (dark filter): for general use in full sun.
Category 4 (very dark filter): for strong lights, in the mountains, for reflecting surfaces, not adequate for guiding.
To choose the best colour for your lens, it is best to ask the advice of an eye specialist because some coloration can produce variations on light, contrast and colour perception.
In conclusion, we have to choose our
glasses based on the use we have for them, and we must remember to make sure that the indispensable quality warranties, the CE marking and the information flyer, are provided.