Sunlight is the most significant source of UV radiation and can damage various ocular tissues. The surface of the eye (snow blindness), the lenses (cataracts, also known as opacity) and the retina (solar maculopathy, macular degeneration) are in particular danger.
UV light consists of UV-A light (leads to skin tanning, but also skin ageing), UV-B light (leads to sunburn and skin cancer) and UV-C light (these are the most dangerous rays, but are almost completely blocked by the ozone layer).
What almost no one knows: Eyes can also get sunburn. The cornea and the conjunctiva are most affected. The highest risk is always when the sunlight is heavily reflected, something that can occur in a snow-covered landscape or when spending time by or in the water.
With the right glasses, however, everyone can optimally protect their eyes from dangerous UV rays. What you should keep in mind when purchasing a pair of sunglasses:
- UV light protection: Sunglasses that absorb at least 99% of UV rays or light rays up to 400 nm.
- Yellow filter: Also called blue blockers because they block all blue light. As a result, the eye perceives the surroundings in a yellowish tint. Benefit: Better contrast for very distant objects, especially on a cloudy or snowy day. Best suited for skiers, hunters, sailors and pilots.
- Polarisation filters: They block diffused light. For example, light reflected off water surfaces or cobble-stone pavement. Particularly useful for driving and fishing.
- Mirror lenses: They reduce the quantity of light reaching the eye, but do not offer any safe protection from UV radiation.
- Side protection: Sunglasses with this function protect the eyes from light entering from the sides.
- Gradient tint lenses: They are dark-coloured in the upper part of the spectacles, light-coloured in the bottom. They thus block the glare from above, but permit normal downward vision for the eyes. They are useful for drivers, but are not recommended for the beach or in snow because a strong glare can come from below.
- Photochromatic lenses: They darken automatically when it is bright and lighten when it is dark. Depending on the UV radiation and the temperature, these processes often take much less than five minutes thanks to new technologies.
- Patients with macular and retinal degeneration. They should always wear glasses with a good UV filter when spending time outside.
- Patients after a cataract operation. These patients’ eyes are particularly sensitive to UV light because the natural lens has been removed and has been replaced by a plastic lens (intraocular lens). Sunglasses with 100% UV protection are necessary with older models because they absorb very little UV light. New intraocular lenses now have UV protection.
- Patients who are taking certain medication. Medication for psoriasis and active pharmaceutical ingredients such as tetracycline, doxycycline, allopurinol and phenothiazin are all so-called “photosensitive medications.” They increase the eye’s sensitivity to UV light. Your doctor will advise you about appropriate eye protection.