Excessive exposure to the sun's UV rays can lead to a sun-burn-like
condition called photokeratitis. This can be extremely painful and make your
eyes red, swollen and watery.
Although the symptoms of photokeratitis normally clear up quickly and
cause no lasting damage to the eye, prolonged unprotected exposure to the sun
can lead to permanently impaired vision.
Sunglasses give comfort in very bright conditions by reducing the amount
of light reaching the eye and protect the eye from damaging UVA and UVB light.
UVB radiation is normally absorbed at the surface of the cornea but can
also reach the retina. Excessive exposure can cause permanent damage to both
the cornea and conjunctiva. However, UVB damage can be halted if further
exposure is avoided.
UVA radiation penetrates more deeply and can cause damage to the
crystalline lens and retina. This
can accelerate the ageing process and increase your risk of developing
cataracts and other age-related conditions which can seriously impair your
What should I look for when buying my sunglasses?
There are three types of sunglasses:
Cosmetic sunglasses these do not give significant protection against the
sun and are worn as fashion accessories.
General purpose sunglasses for reducing glare in bright light. These
should be fine for most occasions including driving and holidays abroad.
Special purpose sunglasses for activities such as skiing or for people
abnormally sensitive to glare.
Always look for British Standard BSEN 1836:1997. This British Standard
sets performance levels for quality, strength, stability, design and
manufacture as well as the amount of UV they let through.
Non UV absorbing lenses can do more harm than not wearing anything at
all. Behind a tinted lens, the pupil opens wider allowing in more UV light
than would happen normally and thus reduces the eyes' natural protection.
Sunglasses sold under BS 2724 have a 'shade number'. Shade numbers
relate to the amount of UV allowed through. The higher the number, the better
Does the colour of the lens make a difference?
Brown and grey are the most popular colours and green is one of the
most effective. However, it is the 'shade number' that counts, not the colour
of the lens.
What about safety?
For safety choose plastic, toughened glass or laminated glass
lenses. This is especially important if you have an active lifestyle or plan
to wear you sunglasses for sports activities.
Should children wear sunglasses?
Yes, children are thought to be at the greatest risk from UV damage
because the cornea, lens and fluids in their eyes are much clearer, allowing
more light to reach the retina. In fact by the age of 18, more than
half-a-lifetime's worth of UV light will have been absorbed by a child's eyes.
Ideally all children - and adults - should wear good quality sunglasses
and a peaked hat when spending time outdoors. It's especially important for
parents to safeguard their children's eyes when they are playing on the beach
or by water where there is a lot of reflected light.
Don't let your child wear toy sunglasses. These offer little UV
protection and can actually cause more damage because the tinted lenses dilate
the pupil allowing more UV light to enter the eye.
Are there such things as 'sun contact lenses'?
Yes. This area is developing quickly. Ask your contact lens
practitioner about the latest products available. Sports people involved in
open-air activities may find these particularly interesting.
What about prescription lenses?
Both sunglasses and contact lenses are available to your normal
optical prescription. Your practitioner will be pleased to advise you, but
ensure that he or she knows that you wish to have UV protection built in.
What are photochromic lenses?
These lenses darken on exposure to sunlight and should react
efficiently in changing light conditions. They should not leave much tint
present when the lens is not exposed to the sun.
What are graduated tints?
These are tinted darker at the top than at the bottom and give
useful protection from bright overhead light, leaving a lighter area for map
reading or seeing the dashboard.
Which sunglasses are best for driving?
The Highway Code states that tinted glasses should not be worn at
night or in poor visibility. Sunglasses should not be used at night to stop
headlamp glare. They should also be removed if driving from bright sun into a
tunnel. Don't pick a very dark tint. A medium density is normally sufficient
and it is safer as it transmits more light.
Are polarising lenses suitable for driving?
These lenses reduce reflections from wet or polished road surfaces,
but they reveal the stress patterns in the older types of toughened
windscreens, which can be hazardous.
The Trust's Top 10 Tips for Safe Sun Vision
1. UV Rays - Expensive sometimes means better, but not necessarily in
the case of sunglasses. What really counts is the degree to which the lenses
filter out harmful UV rays. Look out for glasses carrying the European
Standard 'CE' Mark and the British Standard BSEN 1836:1997, which ensure that
the sunglasses offer a safe level of UV protection.
2. Added Protection - For maximum protection wear a cap or wide-brimmed
hat in addition to your sunglasses.
3. Stay Out of the Midday Sun - Try to avoid being outside when the
sun's rays are strongest between 11am - 3pm.
4. Sunglasses for Driving - When buying sunglasses which will be worn
for driving, make sure they are in the filter category range of 0-3. A lens
carrying a filter category of 4 will be too dark for safe driving. Never wear
sunglasses when driving at night or in poor light.
5. Lens Shade - Unless the glasses carry the British Standard BSEN
1836:1997, do not confuse the shade of the lenses with their ability to filter
UV rays. Dark sunglasses may still allow UV rays to enter the eye and can be
MORE harmful than wearing no glasses at all, because they cause the pupil of
the eye to dilate which allows more UV rays to enter. Therefore, when buying
sunglasses with very dark lenses it is more important than ever to ensure they
offer good UV protection. Sunglasses are marked with a filter category number
from 0-4, where 4 is the darkest lens. Category 4 offers more comfort in
bright sunlight as it avoids straining the eyes.
6. Filtering Blue Light - Ideally sunglasses will also absorb high
energy visible radiation, known as blue light. This will enable the glasses to
be worn for extended periods without tiring the eyes. It is recommended that
no more than 95% of blue light should be filtered to avoid colour distortion.
7. Avoid Scratches - Scratched lenses will scatter the sun's light and
could cause glare around the area of the scratch. Look after sunglasses by
keeping them in a case and cleaning them with a mild detergent and water or a
special lens cleaner. When drying lenses, do not use a paper towel, as this
will scratch the lens. The solution is to use a good cloth, preferably one
made of microfibre.
8. Contact Lenses with Protection - Contact lens wearers can now also
enjoy the added protection of in-built UV protection. Contact lens
practitioners will have details of all the latest products available.
9. Prescription Sunglasses - If you already wear spectacles, you can
have sunglasses made to your prescription.
10. Eye Examinations - Visit your local optometrist for regular eye
examination - this will ensure any long-term sun damage is detected early.
And most of all . . . .
Have Fun! Designs are getting more flamboyant and adventurous, so make
the most of the wide range of sunglasses available and add a real twist to
summer dressing, but make sure that the lenses are big enough to protect the
eyes from stray light. Sunglasses may be vital for protecting the eyes, but
they are also great accessories for looking stylish and individual.