During summer, we are more exposed to solar radiation than during the rest of the year seasons. People is increasingly conscious of the need to protect their skin, but we must also bear in mind that our eyes need the same protection from solar radiation.
Solar radiation can cause damages in the eyes to a larger or smaller extent, depending on the intensity and time of exposure. Therefore, it is essential to protect our eyes from such radiation, especially when we plan to spend a great amount of time exposed to them.
Infrared rays can affect inner eye structures, such as the crystalline lens (cataract) and the retina. They also affect more external areas, such as the conjunctiva and the cornea.
Solar radiation is made of broad spectrum electromagnetic waves that contain a fraction of radiation visible to human eye, that is the light, and another fraction which is invisible.
These are the most harmful rays for the eyes. They specially affect populations located in equatorial regions or regions located at high altitudes, as it is the case of mountain regions, where the eyes are exposed to a higher amount of radiation, as the atmosphere provides lower protection. The ability that surfaces have to reflect the light is also essential. This ability is increased by an 18% on beach sand and by a 20% on water, when compared by a 5% reflected on the earth.
The moment of the day plays also an important role, as radiations are much higher during midday, due to their inclination.
There are three types of ultraviolet rays: UVA, UVB and UVC.
These are the rays responsible for skin tanning effect. Crystalline lens is the main eye element that absorbs them. They have not yet been proved to cause the onset of cataracts.
These are the most harmful rays to our health, and they are the ones most responsible for eye damages such as conjunctivitis and cataracts.
These rays are the most dangerous ones. Fortunately, the ozone layer prevents them from reaching the Earth and causing keratitis or cataracts.
SIGNS AND SYMPTOMS OF DAMAGES
In the conjunctiva, rays can cause several damages, going from irritating conjunctivitis to the onset of a pterygium, a prominent, highly vascularised membrane that invades the cornea and grows towards the pupillary axis, thus causing astigmatism and, sometimes, permanent scarring that endangers good vision.
In the cornea, rays cause superficial keratitis that can lead to photophobia (pain or intolerance to light) and a gritty feeling in the eyes.
In crystalline lenses, cataracts may be formed, and in the retina, scotomas caused by focal burns can lead to a substantial vision loss, in case they affect the central area, as it may be the case when watching an eclipse with no protection.
HOW TO PROTECT OUR EYES FROM THEM?
Eyes have their own solar radiation protection system, composed of eyelids, eyelashes, the cornea, and the crystalline lens, that block a large amount of dangerous radiation and only let a few rays in until the retina. Nonetheless, it is important to protect one’s eyes with sunglasses, in order to prevent light and invisible (infrared and ultraviolet) radiations from harming the eyes and the skin around them.
The fact that eyeglasses lenses are tinted does not guarantee that invisible radiation is prevented from going through them. Therefore, it is important to buy sunglasses in a specialist store that only sells glasses with appropriate filters able to completely protect us from such rays.