Julbo Lenses and the Characteristics of Light
Light is measured in nanometers (Nm); 1 nanometer = 1 millionth of a millimeter.
Light is made up of 3 ranges of waves:
- Ultraviolet rays: short waves from 180 to 380 Nm in length.
- Visible light: medium waves from 380 to 780 Nm.
- Infrared light: long waves from 780 to 1,800 Nm.
Ultraviolet (UV) waves
(5% of solar radiation)Most UV waves are absorbed by the atmosphere. The quantity filtered is very variable: it is only slightly filtered near the equator and at high altitude where the air is thinnest. The extent of the effect of UV waves also increases if the rays reflect off snow, sand or water.
Failure to protect the eyes from UV waves can cause an ophtalmia and temporary or permanent blindness and even irredeemable damage to the conjunctiva and cornea, reducing vision by as much as one-tenth. It should be noted that UV waves are present even in cloudy weather.
Visible light
(39% of solar radiation)As its name indicates, this light is perceived by the brain. It is a good idea to protect the eyes from dazzle caused by excessively bright light. Sunglasses which partially absorb visible light are a comfort concept, and may in fact damage your eyes.
Infrared rays
(56% of solar radiation)They release heat and, in fact, the transparent part of the eye absorbs IR radiation quite naturally as they contain water. In extreme conditions, the cornea is most at risk from this heat.
The following are the places where you may be most at risk from the Sun:
Radiation in the mountains
Radiation in the mountains is extreme, especially in winter. Snow reflects 85% of UV waves and their intensity increases by 10% every 3,000 ft (1000 m).
Dangers:
- Snowblindness, a feeling of having grit in the eye, tears, redness and the loss of several tenths of vision.
- The white-out syndrome, frostbite of the eyelids, watering eyes, loss of contour perception and fear of the light.
In the mountains, it is best to wear wrap-around sunglasses with high-protection lenses.
Radiation at sea
Sand reflects 10% of the rays and water approximately 20%. The higher the hygrometry, the greater the radiation hazard.
Sun and children
Children's eyes, and particularly the eyes of very young children, are more fragile than adults'. UV transmission is total in babies and very high in children under 13 years.
Attention
Sunglasses sold by non-specialists fitted with no protection index are dangerous for children. Tinted lenses cause the pupil to dilate and this admits even more of the harmful rays.
Julbo lenses
- Zebra® is a photochromic lens that adapts to variations in light intensity, with a wide protection range from category 2 to 4. Its activation time is quick, reaching 50% of its capacity in a mere 28 seconds. From shadow to light, Zebra adapts to let you practise your favourite sport in complete freedom.
- Typhoon, in its Cameleon version,
is everything you could wish for in terms of performance at sea:
anti-dazzle, anti-reflection, variable protection depending on light intensity.
Cameleon = polarised + photochromic technology
