Protection from ultra-violet radiation helps protect eyes from conditions like cataracts, early macular degeneration and skin cancers — on the skin around the eyelids — like basal cell carcinoma, squamous cell carcinoma, and melanoma.
It is very hard to avoid the sun but it is easy to protect your eyes by wearing the right sunglasses and these are labelled according to guidelines for UV protection established by the American National Standards Institute (ANSI). Before buying sunglasses look for the ANSI labels and check the colour of the lens as that determines the protection against the UV rays. Lenses with different tints can help you see better hence a quick check with an ophthalmologist can be of great help.
‘Sunglasses are required only for outdoors’
Sunglasses must be used only outdoors. People who work for long hours outdoors need sunglasses as the UV damage to the eyes is slow and cumulates over a person’s lifetime. Those who are close to the equator, at higher elevations or constantly exposed to the mid-day sun have a higher risk of developing sun-related eye diseases. The damage to the eye is not visible in the first decade of life. So protection from the sun’s UV rays must be practiced right from childhood.
Dr Rachna Vinaya Kumar, consultant, paediatric ophthalmology and adult strabismus, at Apollo Hospitals, explains, “Sunglasses are required during summer while outdoors as the level of UV radiation is three times higher than during winter. Similarly they are required at the beach and also for those indulging in winter sports at high altitudes. They must not be worn indoors as the dark glass lenses adapt the vision by increasing photo sensitivity of the eyes and the darker the glasses the more light-sensitive your eyes get. Indoor use thus causes eye strain.”
‘You must Avoid the lenses that cause irritation’
All tinted glasses having the capacity to filter UV rays are good. Ophthalmologists state that dark glasses are useful for people who undergo cataract surgery, lasik surgery and also those who suffer from ailments like conjunctivitis, uveitis and those who have eye problems that make them sensitive to light.
Dr P. Venkata Ratnam, ophthalmologist at Sarojini Devi Eye Hospital says, “Sunglasses are useful in higher altitudes for mountaineering as they protect the eyes from snow blindness. Sunglasses are also useful for people in a tropical country like India. It is very important for the eye to be comfortable after wearing sunglasses. Often we find that certain lenses cause irritation and if that is the case, they must be avoided.”
In Indian cities, sunglasses not only protect from UV rays but also from external allergens and carbon particles from vehicles’ exhaust pipes.
Dr Ratnam says, “Two-wheeler riders are often found to suffer from various allergic ailments due to the pollution that hits the eye. At times small insects get stuck in their eyes, especially during evenings. Sunglasses offer protection from such environmental irritants.”
‘Dark-coloured lens does not Guarantee UV protection’
The colour and degree of darkness of lens does not tell anything about its ability to block UV light. Even a light-coloured lens with 100 per cent UV protection can protect the eyes from UV rays.
Dr Ghanshyam Singh, assistant director and head of L.V. Prasad Eye Optical says, “It has been found that people wear dark-coloured lenses and think that their eyes are protected but that is wrong. It often proves worse for the eye as the pupils get dilated as they are exposed to harmful rays of the sun. People must check for the UV protection ability of the lenses before buying sunglasses. In India, we have found that grey-grey or grey-green with an absorptive value of 70 per cent are good enough for eyes. The grey colour of the lens provides colour transmission throughout the visual spectrum. Seventy per cent density recommendation is sufficient to offer adequate protection for all lenses.”
The Right Lens
- Blue-blocking lenses block blue light and are popular among skiers, hunters, seamen and pilots who use them to heighten contrast.
- Polarized lenses cut reflected glare and are popular with those who play water and snow sports.
- Mirror-coated lenses limit the amount of light entering your eyes and are beneficial during snow skiing on a sunny day.
- Gradient lenses are good for driving as they shield eyes from overhead light and allow more light through the bottom half of the lens so you can see your dashboard clearly.
- Photo chromatic lenses adjust their tint levels based on the amount of UV light.
