Sunshine and shadow
How this topic helps your child's learning
Long before there were such things as clocks, humans used the position of the Sun to help them determine the time of day or the season of the year. An ancient Greek scientist called Eratosthenes used shadows to help him make the first reasonably accurate measurement of the Earth's diameter (but that's another story!).
This module is aimed at pupils aged 7-11 years and looks at how shadows are formed, the position of the Sun in the sky and the concepts of "transparent", "translucent" and "opaque".
The basics
We know, of course, that we should never look directly at the Sun. Sunglasses are a holiday essential - especially on a beach or skiing holiday, when water or snow can intensify the amount of light reaching our eyes.
Frequently Asked Questions
Why should I wear sunglasses?
You should wear sunglasses to protect your eyes against the dangerous rays of the Sun - they can cause permanent damage to your eyes. They have also become an essential fashion accessory and provide comfort for your eyes in sunny conditions.
How can I tell which frames I can have prescription sun lenses in?
You can have prescription sun lenses glazed into any frames that have the Boots Opticians logo lens sticker and ticket.
What is best way to take care of my sunglasses?
To care for your sunglasses you should only clean them with a soft dry cloth - avoid using paper tissues, as these can be abrasive. You can wash your sunglasses in luke warm water with a mild detergent and gently dab dry with a soft cloth. You can use approved lens cleaning solutions, but take care if your lenses have a delicate anti-fog coating. Always store them in the case provided when not in use, if you want extra protection against impact store them in a hard case. Never put the lenses face down on any surface as this may scratch them. Do not leave them exposed to extreme heat as this may damage plastic frames and lenses.
Do children need sunglases?
Yes, you should begin protecting your children's eyes as early as possible as you would protect their skin, as damage to the eyes from UVA and UVB is cumulative.
Will a light tint protect my eyes as much as dark tint sunglasses?
Yes, lens manufacturers put 'UV absorbers' into all their lenses during production just as sun tan lotion manufacturers do with their creams or oils. It is not a question of how dark the lens is. It is a question of the content of the lens.
Are these sunglasses suitable for driving?
If a pair of sunglasses is not suitable for driving and road use requirements there must be a warning on the product by law. Boots do not stock any sunglasses that are unsuitable for driving.
Useful things to know
Ultraviolet rays can damage your eyes and cause cataracts. Wear good quality sunglasses to protect your eyes and the delicate skin around them.
When buying sunglasses, always check what level of protection they provide against UVA and UVB.
The brightness of sunlight is only one factor which could cause damage to our eyes. Sunlight contains potentially harmful UV (ultraviolet) radiation. These radiations are labelled A, B and C. UV-C is filtered out in the upper atmosphere, but the other UV rays can reach the planet's surface and cause harm to skin and eyes.
UVA
- These rays tan your skin and speed up the ageing process.
- Lengthy exposure can cause illnesses including cataracts and cancer.
UVB
- These rays cause sunburn and can quickly damage our eyes.
- Snowblindness is an example of this. It occurs at high altitude where the atmosphere is thinner and sun's radiation is stronger. The powerful rays can quickly cause unprotected eyes to become sticky and painful. Although they usually recover, excessive exposure can cause permanent damage.
Tips & treatments
There are an abundance of lenses and frames available in today's market and the various colours, tints and finishes can be confusing. To help customers make the right choice, all sunglasses are grouped into distinct Filter Categories.
The British Standard for sunglasses has five Filter Categories, ranging from 0 (the lightest) to 4 (the darkest).
NB - Boots do not sell any category 0 filter sunglasses as we believe they transmit too much light to be suitable for general use. Nor do Boots sell any category 4 filter sunglasses as we believe they are too dark, therefore making them unsuitable for road use.
Filter Category 1: These pale tint lenses are most often chosen for style and fashion. Specialist sport lenses can also be Filter Category 1 and will increase definition in dull conditions.
Filter Category 2: These medium tinted lenses make good general purpose sunglasses and they are ideal for driving.
Filter Category 3: The darkest lenses Boots sell, these are best used in strong
sunlight and bright conditions.
Specialist Lenses
While most sunglasses are suitable for everyday wear, some are designed for use when performing specific activities such as mountain biking, snow sports, driving or for protection in extreme weather conditions.
Driving
- Even on a sunny day it's darker inside your car, therefore avoid sunglasses with very dark lenses, Filter Category 2 gives good clarity and clear vision.
- Choose glasses that reduce glare and increase definition.
High Definition
These pale yellow or amber tint lenses help increase contrast and vision in dull conditions
Anti-fog
Specially lined with a hi-tech coating these lenses are designed to stay mist-free during use.
Polarised
- These lenses cut out sunlight reflected off flat surfaces such as standing water on roads, the sea or lakes.
- Because these lenses prevent the Sun's glare off water they're particularly suitable for fishing.
- These lenses are usually available as clip on attachments and are not built into the frames.
Safety
Sunglasses are important for the health of our eyes, for this reason they have to pass numerous safety tests.
The 'Personal Protective Equipment Directive' or PPE Directive:
Under European Law all sunglasses have to pass the PPE Directive
- This directive covers a range of items including motorcycle helmets and it states that 'they must maintain the health and safety of the wearers if used for their intended purpose'
- Non-conformance is a criminal offence - so to show they comply all manufacturers must display the CE Mark
The European Standard BS EN 1836:1997:
European Law also stipulates that all sunglasses must pass the European Standard BS EN 1836:1997
- To pass the Standard, sunglasses are tested for optical quality, UV protection, colour distortion, suitability for road use, construction materials and mechanical strength
- If a product passed these tests it will be shown on the label
The Nickel Directive:
Under European Law, all sunglasses must also be treated to prevent the leaching of nickel - which can cause irritation to the skin.
Sources of help and information
For advice on choosing sunglasses, and other aspects of eyecare, visit: www.bootsopticians.co.uk
The Met Office
Monitors the UV Solar forecast for the UK and Europe, as well as real time
UV data. This information is available at:
www.met-office.gov.uk/weather/
Health Protection Agency - Radiation Protection Division
Records the data that enables the Met Office to provide their UV forecasts.
For more information visit:
www.hpa.org.uk/radiation
Department of Health
Official guidelines on sun care are available at:
www.dh.gov.uk
The information contained on this web site does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.