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FAQ
General

Colour Vision

Eye Sight Problems

Contact Lenses

Spectacles

Night Vision & Driving

UV & the Eye




General

What are your opening hours and the closest Metro line?
Can I purchase a corrective lens spectacle over the counter so as not to waste anyone's time?
How often should I have an Eye Exam?
Am I entitled to a free ΕΟΠΥΥ (ex-IKA) sight test and voucher?
How much am I entitled for glasses or contact lenses?
Give me ten reasons for having an Eye Examination.
Does the employer have to pay for spectacles?
Does wearing glasses make you dependent upon them?
Does sitting too close to the TV damage your eyes?
Can you stop short sight getting worse?
What causes a dry eye?
Are floaters a sign of eye problems?
What age can a child be tested?

Colour Vision

Can defective colour vision be corrected?
Do tinted lenses affect colour vision?

Eye Sight Problems

Short-sightedness (myopia)
Long-sightedness (hypermetropia)
Astigmatism
Presbyopia

Contact Lenses

Can I damage my eyes by wearing my contact lenses inside out?
Is there an age limit to wearing contact lenses?
Are disposable contact lenses safe?
Is it safe to wear contact lenses overnight?
Can I wear contact lenses when swimming?
Can I buy contact lenses over the Internet?
What is contact lens after care?
Do contact lens bifocals work well?
Do contact lenses cause eye infections?
Is tap water bad for contact lenses?
I have astigmatism; can I still get contact lenses?
I want to wear Contact Lenses only to change the colour of my eyes.

Spectacles

Types of Lenses and Coatings

Single-vision lenses
Bifocals
Varifocal or progressive lenses
High-index and aspheric lenses
Prescription sunglasses
Safety and sports glasses
Anti-reflection coating
Scratch-resistant / hard coating
Multi-coated lenses
Photochromic Lenses
What are photochromic lenses?
Why wear photochromic lenses?
Driving in photochromic lenses

Night Vision & Driving

Who suffers from night vision problems?
What is night myopia?
What causes this change?
But surely this means that special glasses are required for night driving?
Even so things do look a little blurred when I drive at night!
I've had my glasses checked but notice haloes and reflections around lights and headlights make my eyes feel uncomfortable. What can I do about this?
Is it just part and parcel of growing old?
I've seen amber night driving glasses advertised in the press. Do they help?
What about the blue night driving lights advertised for use within the car?
What should I do to make sure that I can see as well as possible when driving at night?

UV & the Eye

What is ozone?
Why is the ozone layer important?
What is happening to the ozone layer?
Is anything being done to stop this happening?
Do we know whether or not there has already been a loss in atmospheric ozone
Does this mean that much more short-wavelength UV radiation is reaching the ground?
When do I need to protect my eyes against short-wavelength UV radiation from the sun?
How can I protect my eyes?
Do I still need protection when the sky is cloudy?
Are the risks likely to get worse in the future?
If I have exposed my eyes to too much short wavelength UV radiation, how will I know?
What are polarised lenses?


General

1. What are your opening hours and the closest Metro line?

Closest Metro: Halandri and Agia Paraskeui.
Line: Blue Click here for Map
Opening Hours: more information in our index page

2. Can I purchase a corrective lens spectacle over the counter so as not to waste anyone's time?

Readymade reading spectacles to correct presbyopia only (which is the condition which happens as we get older and need a prescription to read but not to see in the distance) can be sold by anyone. These spectacles are limited in that they have a maximum prescription of +4 Dioptres, right and left lenses are identical and the have a fixed PD usually of 60mm. You should not avoid having your eyes examined regularly (at least every 2 years) as an eye examination does not only check your sight but it also examines the health of your eyes. Many conditions, such as glaucoma, are more common as we get older and do not cause any symptoms until permanent visual loss has occurred.

3. How often should I have an Eye Exam?

It is generally recommended to go to an ophthalmologist every two years if you do not have any symptoms of change in your vision. If there are problems, then every time your ophthalmologist has instructed you.
Here is a general directional guide for your convenience:

a. Below the age of 7 with impaired vision and use of glasses - every 6 months
b. From 7 years to 16 years with impaired binocular vision, or myopia, which rises rapidly - every 6 months
c. Up to 16 years without problems of binocular vision - once a year
d. Over 16 years to 70 years - every two years
e. More than 70 years - once a year

● If someone is over 40 years and with history of glaucoma in the family or have high eye pressure - usually once each year
● If someone has diabetes - usually once each year.

For more information visit the site of the Ophthalmology Society
www.eyenet.gr

4. Am I entitled to a free ΕΟΠΥΥ (ex-IKA) sight test and voucher?

Your eligibility is subject to certain conditions. An ΕΟΠΥΥ or equivalent subsidised eye exam is allowed every 4 years according to current guidelines (2013), but some exceptions apply. Call us in order to advise you on your eligibility. For ΕΟΠΥΥ appointments call 14554

5. How much am I entitled for glasses or contact lenses?

The amount received varies depending on your insurance, but for ΕΟΠΥΥ you are entitled one hundred euro every four years.
(ΕΟΠΥΥ document)

6. Give me ten reasons for having an Eye Examination.

 The eye examination is a vital health check and should be part of everyone's normal health regime. Here are 10 important reasons to have a regular examination:

1. You only have one pair of eyes. Once lost, your eyesight may never be replaced.
2. Unlike your teeth, your eyes do not usually hurt when there is something wrong.
3. The eye examination can pick up early signs of potentially blinding eye conditions, such as glaucoma.
4. The earlier a problem is detected the greater the chance of successful treatment. This is particularly true for young children and the elderly.
5. The eye examination can also detect a number of other underlying health problems, such as high blood pressure or diabetes.
6. An examination checks whether your eyesight needs correcting with spectacles and determines the best form of correction for your vision.
7. Good vision means working and playing better and safer - in fact it means a better quality of life.
8. For young people, good eyesight is vital for learning. An eye examination will detect any problems in sight which may be affecting school performance.
9. Failing eyesight is often taken for granted as people get older. However, by having an eye examination and remedying problems in eyesight, older people can improve their quality of life significantly.
10. Poor eyesight is dangerous. Make sure that you meet the legal requirement for driving.
Unless otherwise advised you should have an eye examination every two years. It may be necessary to have examinations more frequently depending on your age and medical history. Your Ophthalmologist is the best to decide.

7. Does the employer have to pay for spectacles?

In certain cases and only if they are needed for Video Display Units (VDU) and no other task (e.g. reading)*. You could consider looking at the insurance schemes as yours might include covering the cost of glasses.

8. Does wearing glasses make you dependent upon them?

There is no evidence to suggest that wearing spectacles makes you more dependent on them. Most people need to wear spectacles more as they get older, particularly if they are long-sighted, and wearing spectacles does not increase (or decrease) this dependence. If you go short sighted when you are in your teens this is because your eyes are growing (short sighted eyes are too big) and this also tends to get worse whether or not you wear your spectacles. What people find is that, when they get their first pair of spectacles their vision is so much clearer and more comfortable with the spectacles than without them, they are reluctant to use the effort to see without them. They are then surprised when they take their spectacles off that their vision is apparently worse without them than they remember it being. In fact, their vision is not actually worse without specs than it was before they had the spectacles, but they have become accustomed to seeing more comfortably because they have spectacles.

9. Does sitting too close to the TV damage your eyes?

There is no evidence that sitting close to the TV causes any harm to the eyes. Television should be watched with the lights on, rather than off, as this should be more comfortable because otherwise it is like looking at a (big) torch.

10. Can you stop short sight getting worse?

Short sight is usually caused because the eye is too big or the cornea is too steeply curved. That is why it tends to happen during the growth spurt of puberty. Whilst you cannot control how large (or long) your eye becomes, some people believe that wearing rigid contact lenses may slow down the progression of the short sight by reducing how steep the cornea becomes.

11. What causes a dry eye?

Dry eyes can be either due to a problem with the quality of the tears or with the quantity of tears available. The differences may depend on age, diet, health, contact lens wear, atmosphere, medicines or occupation. Depending on the cause the treatment may be hot compresses or just the use of tear supplements. Your practitioner will be able to advise after further investigation.

12. Are floaters a sign of eye problems?

Most people, particularly if they are short sighted, have some floaters inside their eyes. These appear as little black spots or 'flies' which appear to float around in front of your sight. They move when you move your eyes and are normally more obvious when you are looking at a plain pale background (like a cloudless sky). They are normally quite innocent, but if you get a shower of floaters, if you see lots of floaters after you have banged your head, or if you see flashing lights in your eyes or a 'curtain' or 'veil' in front of your eyes you should seek urgent medical attention.

13. What age can a child be tested?

Children can have their eyes examined as soon as they are old enough to open their eyes. They do not have to be able to read the letters, or even speak (although it helps if they can !). If there is a family history of a lazy (amblyopic) eye, a squint, or needing very strong spectacles as a young child, it is vital that you take your child for an eye examination.

Colour Vision

1. Can defective colour vision be corrected?

Most people who have poor colour vision are born with the condition (it is congenital). It is hereditary and mainly affects males. There is no cure for congenital colour defects, but some people find it useful to have special tinted spectacles or contact lenses where the tint in one eye is different from that in the other. Although this does not restore the appearance of colours it may enable you to be able to distinguish between certain colours more easily by comparing the appearance of the colour through one eye with that through the other. However, this will not enable you to get a job which is not open to those with defective colour vision.

2. Do tinted lenses affect colour vision?

Tinted lenses which look coloured change the colour of things you look at through them. If both lenses are tinted the same colour (as is usually the case) this will change the colour of everything you look at through them and may make certain objects difficult to see. Because a tint reduces the amount of light that enters your eyes, we do not recommend you use tinted lenses for driving at night, or in conditions of poor visibility where light is at a premium.

Eye Sight Problems

Short-sightedness (myopia)

Short sight occurs when light is focused in front of the retina causing distance vision to become blurred. Near vision, however, is usually clear. Short sight normally develops in childhood or adolescence and is often first noticed at school. Glasses may need to be worn all the time or just for driving, watching TV or sports.

Long-sightedness (hypermetropia)

Long sight occurs when light is focused behind the retina rather than on it, and the eye has to make a compensating effort to re-focus. This can cause discomfort, headaches or problems with near vision. Glasses may need to be worn all the time or just for close work, such as reading, writing or computer use. In older people, as re-focusing becomes more difficult, distance vision may also become blurred.

Astigmatism

Astigmatism occurs when the curvature of the cornea or lens is not perfectly round. It is sometimes described as the eye being shaped like a rugby ball rather than a football. Most people have a small amount of astigmatism, which may not need correcting. If vision is blurred or headaches occur, your Ophthalmologist may recommend glasses are worn all the time or just for specific tasks.

Presbyopia

Presbyopia is the loss of focusing ability that occurs naturally with age. In younger people, the lens is very flexible and the eye has a wide range of focus from far distance to close up. As you get older, the lens slowly loses its flexibility leading to a gradual decline in ability to focus on near objects. Presbyopia is not a disease but a normal and expected change which sooner or later affects everyone, whether you already wear glasses or contact lenses or not. Around the age of 40-45, you will begin to notice that you are holding the newspaper further away or need more light to read small print. There is no advantage in delaying using reading glasses, or changing to bifocals or varifocals. They will not make the eyes lazy. Your optometrist will advise you on the best form of vision correction to suit your individual lifestyle and occupation.

Regular examinations are important throughout life, whether or not you are experiencing problems with your eyesight.

Contact Lenses

1. Can I damage my eyes by wearing my contact lenses inside out?

It can sometimes be difficult for a new contact lens wearer to determine whether a soft lens is inside out or not. If it is inside out it is unlikely to damage your eye - all that will happen is that it will feel uncomfortable, your vision may be blurry, and it may come out of your eye (or on to the white of your eye).

2. Is there an age limit to wearing contact lenses?

The age at which contact lenses can be fitted depends upon the maturity of the child. This is a matter for the professional judgement of the practitioner. Older people may find they have problems handling contact lenses and may also find that their eyes are too dry to wear contact lenses. Again, this should be discussed with your practitioner.

3. Are disposable contact lenses safe?

Most modern contact lenses are safe, if they are handled correctly and you go for regular check-ups and take the advice of your practitioner.

4. Is it safe to wear contact lenses overnight?

Some contact lenses are designed so that they can be worn overnight but extended wear does increase the risk of serious contact lens problems. Therefore, you should discuss this with your contact lens practitioner to decide whether or not these are suitable lenses for you.

5. Can I wear contact lenses when swimming?

There are some micro-organisms which live in swimming pools which can cause very serious eye infections if they get into your eyes. We suggest you discuss this with your contact lens practitioner.

6. Can I buy contact lenses over the Internet?

Contact lenses must be sold by, or under the supervision of, a registered optician. They must also be to a recent prescription (within one year). Some Internet companies are able to supply contact lenses if you give them a copy of your prescription. You must make sure that you have your contact lens check-ups done regularly.

7. What is contact lens after care?

This is the name for contact lens check-ups. It is important to ensure that you have regular contact lens after care, at least once per year, to ensure that the contact lenses are suitable for you and are not harming your eyes. Even if you are not having any problems with your lenses, the aim of the after care is to spot problems before they may become serious.

8. Do contact lens bifocals work well?

Some people find that bifocal contact lenses work well enough for them to see everything they need to see. The problem with bifocal contact lenses is that, unlike bifocal spectacles, it is not easy for the wearer to look through different parts of the lens for different tasks, as the lenses move with the eyes. There are many different designs of bifocal and multifocal contact lenses so you may find that you are more successful with one design than the other. This is best discussed with your contact lens practitioner.

9. Do contact lenses cause eye infections?

Because contact lenses actually touch your eyes they must be clean and sterile before you insert them. It is possible to get eye infections even if you do not wear contact lenses, but the risk of contracting an eye infection is greater if you wear contact lenses (particularly if you use tap water on your lenses or wear them overnight). Modern contact lenses, if fitted and handled properly, are a very safe form of vision correction, but you should discuss this with your contact lens practitioner.

10. Is tap water bad for contact lenses?

There is a significant increased risk of eye infection if tap water is used with your soft contact lenses - bugs that live in the water can cause devastating eye infections, the risks are less so with hard gas permeable materials. It is safest not to use it water at all but to use sterile saline solution instead.

11. I have astigmatism; can I still get contact lenses?

Astigmatism can be corrected using contact lenses. These may either be toric soft lenses, or toric or conventional gas permeable lenses. Your practitioner will advise you as to the best type in your case.

12. I want to wear Contact Lenses only to change the colour of my eyes.

Plano (cosmetic) contact lenses are non-prescription contact lenses with colours and/or patterns on the surface. Like all contact lenses, these novelty lenses sit directly on the front surface of the eye and, as such, must be treated with the same degree of care as other lens types.
Under new regulations introduced in June 2005, plano cosmetic contact lenses are now regulated in the same way as powered lenses and may only be fitted by or under the supervision of a registered clinician.  Your contact lens practitioner will advise you on the most suitable lens type, wearing schedule, replacement frequency and care regime. Regular aftercare check-ups, at intervals specified by your practitioner, are essential to ensure that your eyes remain healthy and that you are using the best lenses for your particular needs.  It is essential that wearers take proper care in cleaning and disinfecting these novelty lenses and their storage cases. Only use the care products recommended by your practitioner and follow the instructions carefully. When properly fitted and cared for, plano cosmetic lenses should provide trouble-free use. However, it should be remembered the incorrect use of contact lenses can lead to serious ocular complications. (More advice on looking after contact lenses)

Spectacles

Types of Lenses and Coatings

Single-vision lenses

The simplest form of spectacle or contact lens is the single-vision lens, made to a single prescription to correct a particular eyesight problem. Concave lenses are used to correct short sight and convex lenses to correct long sight. Concave lenses are generally thinner in the centre than they are at the edge and convex lenses are usually thinner at the edge than at the centre. The curvature of the lens, its thickness and weight will depend on the amount of long or short sight it is designed to correct. The lens material will also influence the thickness and weight of your lenses, as will the size and shape of the spectacle frame you choose. Traditionally, spectacle lenses were made of glass but most lenses are now lightweight plastic and there is a wide range of materials available to suit your prescription and lifestyle.

Bifocals

Bifocal lenses contain two optical corrections with a distinct dividing line between the two parts. The most common use of bifocals is for people who have become presbyopic and need a different prescription for close work. The upper part of the lens corrects distance vision and the lower half is for near vision. Trifocals are also available that have three sections and incorporate a correction for intermediate vision. Bifocals and trifocals come in a range of designs but nowadays varifocal lenses are much more likely to be prescribed.

Varifocal or progressive lenses

Varifocal lenses, also known as progressive lenses, are used for correcting presbyopia but unlike bifocal lenses have no visible dividing lines between the different corrections. Instead they have a graduated section in which the power of the lens progresses smoothly from one prescription to the other, allowing the wearer to see clearly at all distances. These lenses also have the benefit of looking better - they don't draw attention to the ageing process. A range of varifocal designs is available depending on your lifestyle and occupation. Modern lens technology means that there are many different designs and materials to choose from. Your optometrists or dispensing optician will be able to advise you on the best lenses to suit your individual requirements.

High-index and aspheric lenses

If you need high-powered lenses you can improve the weight or appearance of your glasses with special lens materials and designs. High-index materials and aspheric designs mean that lenses can now be made thinner, lighter and better looking than traditional lens types. High-index materials make lenses for short sight thinner, while aspheric designs that minimise the amount of material make lenses for long sight both thinner and lighter.

Prescription sunglasses

Whatever your prescription, it is important to protect the eyes against excessive ultraviolet (UV) radiation. Protection is needed to avoid reflected light from sand and snow or if you spend long periods out of doors, particularly in the summer. Prescription sunglasses can be made with single-vision, bifocal or varifocal designs to offer the same standard of protection as non-prescription sunglasses.

Safety and sports glasses

Special lenses and frames incorporating eye protection are available for a variety of safety and recreational uses.

Anti-reflection coating

Spectacle lenses can be provided with anti-reflection coatings which virtually eliminate distracting reflections off the lens surfaces. Reducing reflected light is particularly helpful for computer users and for night driving. Anti-reflection coatings also improve the cosmetic appearance of your glasses and can make thick lenses look thinner.

Scratch-resistant / hard coating

Plastic lenses are lighter than traditional glass lenses but they scratch more easily. Scratched lenses can be irritating for the wearer and look unsightly. Scratch-resistant coatings are available to protect against damage and prolong lens life.

Multi-coated lenses

Multi-coated lenses uncorporate a combination of coatings - anti-reflection, scratch-resistant, water repellent and UV - to combine to improve the properies of your spectacles.

Photochromic Lenses

Photochromic lenses react to light so that indoors or in dull conditions they have a light tint, and in bright light they darken to eliminate glare and protect the eyes against UV. Modern photochromic materials react and fade quickly, suit most prescriptions and are more likely to be lightweight plastic than glass.

What are photochromic lenses?

Photochromic lenses are lenses that change their colour according to light conditions. When exposed to sunlight they darken quickly to eliminate glare and to protect the eyes against UV. These lenses are generally nearly clear when it is dark.

Why wear photochromic lenses?

Many people wear these lenses and find them convenient, as they automatically darken in the sunshine and can avoid the need for you to carry prescription sunglasses. Modern photochromic materials react and fade quickly, suit most prescriptions and are more likely to be lightweight plastic than glass.

Driving in photochromic lenses

Concern has been raised about whether it is safe to use photochromic lenses for activities in low light conditions where vision is critical - such as driving at night. Several factors should be considered:
1. Any tint will reduce the amount of light that is entering your eye. The darker the tint the more the light will be reduced. You should not wear a dark tint for night driving.
2. We generally see better in the light than in the dark so the more light that enters your eye the better (providing it is not dazzling you).
3. As some light is lost from reflection from the lens surfaces, the performance of all lenses is enhanced if they are coated with an anti-reflection coating to reduce the reflections from the front and back surfaces of the lens. This is particularly important for the thinner, high index lenses. Your optometrist or dispensing optician will be able to advise you on this.
4. The amount of light transmitted by modern photochromic lenses in their clear state with a multi anti reflection coating, is not much less than that transmitted by a clear, non photochromic lens without an anti reflection coating.
5. Some of the older photochromic materials do not go as clear as the newer photochromic materials. We recommend that you choose the best lens that you can afford, particularly if you wish to use the lenses for critical vision at night.
6. The performance of some of the older photochromic materials degrades over time If you notice that your photochromic lenses do not go as clear as they used to you should buy a new pair.
7. Older people need more light entering their eyes than younger people do. This is because the eye naturally absorbs more light as it ages, meaning that you need more light going into it for the same amount of light to reach the retina.
8. When driving you may find your photochromic lenses do not become as dark as they do outside. Car windscreens (and windows) filter and absorb most of the short wavelength light (near UV) that would normally trigger the darkening process.

For further advice, contact your optometrist or dispensing optician who will be able to advise you on which particular lens is most suitable for you.

Night Vision & Driving

This information on night vision problems and driving has been produced jointly by the College and the Association of Optometrists-UK.

Who suffers from night vision problems?

Most of us are aware that driving at night is more demanding and stressful than driving in the daytime. We make natural compensations for this as we drive but it is a fact that the number of night and road accidents is much greater than those that occur during the day.

What is night myopia?

Some years ago, the term ‘night myopia’ was first used and some people advocated special night driving glasses to correct it. Myopia is what is generally known as short sight. Short-sighted people can see near objects clearly while distant objects are blurred. It is a problem that occurs in all conditions and light levels but research has shown that, at very low light levels, well below those experienced when driving at night with headlights on, younger people with otherwise perfect vision become temporarily myopic.

What causes this change?

Normally people below the age of about 40-45 can adjust the focus of their eyes between long and short distance at will. However, in very dark conditions this system breaks down and the focus of the eyes settles to a constant distance of about 1m.

But surely this means that special glasses are required for night driving?

Yes, that is logical reasoning and it is true that, if a driver's eyes were constantly focused at 1m, the distant road ahead and on-coming traffic would appear blurred. Fortunately, however, we do not suffer this fixed focus. Modern road and vehicle lighting provides sufficient light for the focusing system of the eye to work normally: even when there is no overhead street lighting.

Even so things do look a little blurred when I drive at night!

Road lighting levels at night are obviously lower than those found by day. This causes the pupil of the eye to become larger during night driving than under brighter conditions and the increase in pupil size can accentuate any existing small errors in focusing, causing blur. If you notice such a blur, your current glasses or contact lenses may need changing or you may need an optical correction. Your optometrist can advise you on this.

I've had my glasses checked but notice haloes and reflections around lights and headlights make my eyes feel uncomfortable. What can I do about this?

The most common reason for haloes and reflections is a dirty windscreen (both inside and out). In the same way scratched or dirty spectacle lenses can contribute to unwanted scattered light, as can condensation on any of these surfaces. It is a good idea always to clean your windscreen and glasses before night driving. Reflections from the surfaces of spectacle lenses can sometimes cause multiple images of lights at night. If you notice these, effective anti-reflection lens coatings are available. Ask your optometrist for details.

Is it just part and parcel of growing old?

Unfortunately a variety of changes in the eye can contribute to discomfort from glare during night driving, particularly among older drivers. This is commonly caused by cataracts which produce effects similar to looking through a dirty window. Spectacles can do nothing to overcome this and it may be sensible to minimise night driving. If you are affected by oncoming headlights, try concentrating on the nearside kerb as you drive - but don't forget to reduce your speed!

I've seen amber night driving glasses advertised in the press. Do they help?

There is no evidence that these lenses improve vision on the road, indeed tinted lenses may actually make vision worse. Windscreen tints have the same effect and this is why the Highway Code warns drivers not to use any form of tint at night.

What about the blue night driving lights advertised for use within the car?

These cause the eye pupil to contract and may therefore reduce the glare from approaching headlights but they also make it harder to see the road ahead. They are not recommended.

What should I do to make sure that I can see as well as possible when driving at night?

Make sure that your eyes are examined regularly
Always wear an up-to-date pair of distance spectacles or contact lenses
Keep a spare pair in the car if possible
Do not use tinted lenses but have them anti-reflection coated if necessary
Don't forget to keep the windscreen clean, inside and out, at all times
Make sure your car's lighting is working properly
Finally, if in doubt about the fitness of your vision for driving at night, seek your optometrist's advice.

UV & the Eye

This information on the effects of depletion of the ozone layer and the risk from excessive ultraviolet radiation has been produced jointly by the College and the Association of Optometrists.

What is ozone?

Ozone is a form of oxygen in which three oxygen atoms join together to form a molecule of ozone (03). It is formed by the action of sunlight on molecules of ordinary oxygen in the stratosphere. Thus, it is mainly scattered in a ‘layer’ at altitudes between about 10 and 30km above the earth's surface. Some ozone can also be formed close to the earth's surface by the action of sunlight on, for example, car exhaust fumes.

Why is the ozone layer important?

As well as emitting visible light, the sun also emits short-wavelength ultraviolet (UV) radiation. The ozone layer absorbs the shorter, more hazardous, UV wavelengths and hence prevents them from reaching the earth's surface. This short-wavelength UV radiation can affect human health by causing skin cancer and affecting the immune system. It also contributes to various types of damage to the eyes (eg photokeratitis or snow blindness, and various opacities on and within the eyes, including pingueculae, pterygia and cataract).

What is happening to the ozone layer?

The ozone layer is being damaged by various man-made chemicals (eg chloro-fluorocarbons, or CFCs), which find their way from the earth's surface up to the stratosphere and break down the ozone molecules.

Is anything being done to stop this happening?

A large number of nations have signed the 1987 Montreal Protocol and its later amendments which restrict the production of these damaging chemicals. However, because these chemicals survive a long time in the atmosphere, some loss of ozone will persist for at least another 50 years. Worries remain too, that some nations may still continue to produce these chemicals.

Do we know whether or not there has already been a loss in atmospheric ozone

Yes. Measurements made from satellites, rockets and the ground all show that at certain times of the year, the ozone layer thins by 50% over the South Pole. Fortunately, losses over Britain and other non-polar regions are very much smaller (about 4% per decade since 1979).

Does this mean that much more short-wavelength UV radiation is reaching the ground?

Yes, at the South Pole. Currently, little evidence shows that UV levels have increased in Europe and other non-polar regions, although the situation is being carefully monitored to make sure that this does not occur.

When do I need to protect my eyes against short-wavelength UV radiation from the sun?

At present, the risks to the eyes are not substantially greater than they have been in the past. Amounts of potentially damaging solar UV have always been greatest at around local noon in mid-summer. They increase as we move towards the equator or to higher altitudes. Sand and snow tend to reflect substantial amounts of UV and hence increase damage risks. Protection is certainly needed during skiing or other activities on snow at high altitudes (particularly during summer) or on beaches, especially when these are near the equator.

How can I protect my eyes?

Wearing a broad-brimmed hat considerably reduces the amount of light striking the eyes when walking or standing. Ordinary clear plastic or high-index glass lenses provide considerable protection against short-wavelength ultraviolet radiation. Sunglasses provide still better protection, although it is important to check that these are made to meet the Standard for sunglasses (e.g. BS EN 1836:2005): category 2 (20% transmittance) give good protection for cloudy winter days. Protection against ambient ultraviolet coming from the side or reflected from below is also desirable, and with some modern small sized frames, care must be taken to check that they also protect from above.

Do I still need protection when the sky is cloudy?

Many types of cloud have only a small effect on the amounts of ultraviolet reaching the ground. lt is, then, prudent to continue to protect the eyes from ambient ultraviolet in high-risk environments even when the sky is cloudy. A cloudy sky may still give high reflectance such as white sand beaches and you should certainly wear protection.

Are the risks likely to get worse in the future?

Scientists hope that the signing of the Montreal Protocol will stop the decrease in the ozone layer and make sure that we remain reasonably protected against short-wavelength UV sunlight. However, it is very difficult to predict exactly what will happen and a very careful worldwide watch is being kept on levels of both ozone and UV so that any worsening of the problem can rapidly be identified.

If I have exposed my eyes to too much short wavelength UV radiation, how will I know?

A few hours after the exposure your eyes will redden and water. They may feel ‘gritty’ and you may be more comfortable in a darkened room. Fortunately, this photokeratitis will subside within one or two days. The possibility of long-term effects cannot be excluded, however, so that it is worthwhile protecting your eyes when at risk in the future.

What are polarised lenses?

Polarised lenses take advantage of the nature of the light. This happens by allowing light to pass through one meridian of the lens whilst the rest is eliminated. The result is that they cut out the glare reaching the eyes. This can be quite useful for the fisherman, the professional driver and generally people being exposed to extreme sunlight and glare situations.They can also be made with your glasses prescription.


* We wish to thank the College of Optometrists for allowing us to duplicate part of their FAQ material intended for the General public.
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