Photochromic Lenses

"Photchromic lenses are sometimes referred to as transition lenses, reactalite lenses or sunsensor lenses.
Photochromic lenses darken on exposure to sunlight and protect the eyes from ultraviolet radiation. Excessive exposure can cause permanent damage to the cornea and conjunctiva. Good photochromic lenses block out 100% of the most harmful rays of the sun, 100% of the time, adapting to changes in light and darkening in seconds.

Whilst sunglasses give comfort in very bright conditions by reducing the total amount of light and glare reaching the eye, they are not always convenient in changing light conditions and care must be taken that they meet Standard BS 2724 otherwise they won’t protect the eye from the sun’s damaging ultraviolet rays. In fact, non-UV absorbing lenses can do more harm than not wearing any protection at all because, behind a dark tint, the pupil increases in size allowing the harmful rays through."

Keep an eye on drivers’ sight - India

"An eye test carried out on 1,000 drivers in the city of THIRUVANANTHAPURAM in INDIA gave a less than encouraging result – 560 had defective eyesight.

Drivers’ defective eyesight and their rampant misuse of headlights are fast becoming a hazard for road users and a matter of grave concern for law enforcing agencies.

An eye test carried out by the National Transportation Planning and Research Centre (Natpac) in the city among 1,000 drivers revealed that 560 of them, mostly in the 40-50 age group, had defective eyesight.

According to Natpac scientist T. Elangovan, 10 per cent of the drivers had serious problems like tunnel vision, blurred vision and colour blindness.

According to a senior police official, increase in night time road accidents involving heavy vehicles is mainly due to poor eyesight of the drivers.

Other major culprits are the drivers’ reluctance to dim headlights, misuse of high-beams and use of halogen bulbs in headlights.

Two-wheeler and light motor vehicle drivers often complain that they get blinded by the high-beams used by luxury buses and heavy vehicles, especially those transporting cargo. High-beams are banned in the city. But, all four-wheelers and heavy vehicles prefer to move with the high-beam switched on.

There have also been several instances of two-wheelers and cars colliding with traffic dividers and lamp posts after the drivers are momentarily dazed by the high-beam from the approaching vehicles.

Many vehicles, especially luxury buses, install additional powerful headlights after getting the vehicle registered. The additional lights are removed when the vehicles are taken for CF (Certificate of Fitness) test, Motor Vehicle Department officials say."

Treatment For Squint

"Treatment varies accordingly to the type of squint. An operation is not always needed. The main forms of treatment are:

• Spectacles - to correct any sight problems, especially long sight.
• Occlusion - patching the good eye to encourage the weaker eye to be used. This is usually done under the supervision of an orthoptist.
• Eye drops - certain types of squint can be treated with the use of special eye drops.
• Surgery - this is used with congenital squints, together with other forms of treatment in older children, if needed. Surgery can be performed as early as a few months of age."

What Causes A Squint

"There are several types of squint. The cause is not always known, but some children are more likely to develop it than others. Among the possible causes are the following:


Congenital squint
Sometimes a baby is born with a squint, although it may not be obvious for a few weeks. In about half of such cases, there is a family history of squint or the need for spectacles. The eye muscles are usually at fault. If squint is suspected, it is important that the baby be referred for accurate assessment at the earliest opportunity. Sometimes a baby has what is known as ‘pseudo squint’ which is related to the shape of the face and this does not require any treatment, but a baby with a true squint will not grow out of it and requires careful assessment and due treatment.

Long sight (hypermetropia)
Long sightedness can sometimes lead to a squint developing as the eyes ‘over-focus’ in order to see clearly. In an attempt to avoid double vision, the brain may automatically respond by ‘switching off’ the image from one eye and turning the eye to avoid using it. If left untreated, a ‘lazy eye’ (amblyopia) may result. The most common age for this type of squint to start is between ten months and two years, but it can occur up to the age of five years. It is usually first noticed when a baby is looking at a toy, or at a later age when a child is is concentrating on close work, such as reading.

Childhood illnesses
Squint may develop following an illness such as measles or chickenpox. This may mean that a tendency to squint has been present but, prior to the illness, the child was able to keep his or her eye straight.

Nerve damage
In some cases a difficult delivery of a baby or illness damaging a nerve can lead to a squint."

Squint

"A squint (also known as a strabismus) is a condition that arises because of an incorrect balance of the muscles that move the eyes, faulty nerve signals to the eye muscles and focusing faults (usually long sight). If these are out of balance, the eye may turn in (converge), turn out (diverge) or sometimes turn up or down, preventing the eyes from working properly together.
Squint can occur at any age. A baby can be born with a squint or develop one soon after birth. Around 5 - 8% of children are affected by a squint or a squint-related condition, which means one or two in every group of 30 children. If a child appears to have a squint at any age from six weeks onwards, it is important to seek professional advice quickly. Many children with squints have poor vision in the affected eye. If treatment is needed, the sooner it is started the better the results.
Squint can be a complex condition and not every situation is covered here. Your optometrist will be pleased to give further advice, if needed. Children will benefit from support and encouragement during treatment and you should not be afraid to ask questions which will help you understand the condition. The successful outcome of treatment depends upon everyone co-operating."

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 lens materials and aspheric designs mean that lenses can now be made thinner, lighter and better looking than traditional lens types. High-index materials and aspheric lens design make lenses for short sight and long sight thinner and allows more optimal vision through the lens area away from the centre of the lens"

VDU's and Your Eyes - Prescription Glasses

"Only a small proportion of users will need spectacles specifically for working at a VDU and the majority of these will be what is known as presbyopic. Presbyopia affects us all as we get older. Around the age of 45 people begin to find they lose the ability to focus on objects that are close up.

Spectacles with single vision, bifocal or varifocal lenses can all be used successfully for VDU work. Contact lenses are also suitable, but wearers should try to blink regularly which keeps the lenses comfortable.

When you concentrate on the screen for long periods, your normal blinking rate slows down. Presbyopic contact lens wearers may need additional reading glasses.


Reflection-free lenses
Reflection-free lenses are well worth considering for VDU users. Because they eliminate almost all reflections VDU glare is considerably reduced, providing clearer and sharper vision."

VDU's and Your Eyes

"The following precautions can lead to eye strain relief caused by VDU work:

Take frequent breaks
When you work at a VDU your eyes can be focused on the screen for long periods so it is important to take a brief rest and give your eyes a break every 20 minutes or so. You should have sufficient space behind the screen for you to be able to look beyond it and relax your eyes.


Screen settings and position
You should adjust your VDU to levels of brightness and contrast that you find comfortable. Keep the screen clean and free of dust and fingermarks. If possible, position it so that windows or other light sources are to the side rather than in front or behind it – if you can see a window or light unit reflected in the screen, move the VDU until the reflections disappear, or adjust blinds or curtains. The surface of the screen should be between 33 and 100cm from your eyes and if you are working from copy documents these should be placed at roughly the same distance to avoid continual re-focusing.


Lighting
Try to eliminate as much glare as possible from the region around your screen. This is not always straightforward, but as a general rule:

•The office lighting should be set at a level which allows the documents and screen to be read easily. Additional lighting – such as an Anglepoise lamp – may sometimes be necessary to achieve this.

• Avoid an uncurtained window directly in front of or behind your working position

• Any window reflected in the screen should be fitted with blinds or curtains

• Walls and desk surfaces should be non-reflective and neutral in colour

Anti-Reflective Glasses

Use anti-reflective lenses when using/wearing glasses for VDU work. This reduces eye strain."

VDU's and Your Eyes

"Although there is no reliable evidence to suggest that even long-term intensive use of VDUs is damaging to the eyes, it is true that VDU users tend to complain of eye strain more than non-users. This is likely to be due to fatigue through causes such as:

• Insufficient and infrequent rest periods

• Incorrect positioning of the screen and/or documents

• Unsuitable lighting

• Poorly designed work area

• An uncorrected eyesight fault such as long sight, short sight, astigmatism or presbyopia

• The eyes not working together comfortably.

Any of these conditions could lead to fatigue; all can be overcome through good design of the working environment and by regular eyecare."

Astigmatism - Signs & Symptoms

"If you have only a small amount of astigmatism, you may not notice it or have just slightly blurred vision. But sometimes uncorrected astigmatism can give you headaches or eyestrain, and distort or blur your vision at all distances.
It's not only adults who can be astigmatic. In a recent study of 2,523 children at Ohio State University School of Optometry, more than 28 percent of them had astigmatism. Children may be even more unaware of the condition than adults, and they are unlikely to complain of the blurred or distorted vision. Unfortunately, astigmatism can affect their ability to see well in school and during sports, so it's important to have their eyes examined at regular intervals in order to detect any astigmatism early on. In the U.K, it is recommended that children under the age of 16 should have their eyes tested at least once every 12 months."

Astigmatism

"Astigmatism is one of the most common vision problem.
It may accompany nearsightedness or farsightedness. Usually it is caused by an irregularly shaped cornea (called corneal astigmatism). But sometimes it is the result of an irregularly shaped lens, which is located behind the cornea; this is called lenticular astigmatism. Either kind of astigmatism is usually corrected with eyeglasses or contact lenses"

Myopia

"The global prevalence of refractive errors has been estimated from 800 million to 2.3 billion.[20] The incidence of myopia within sampled population often varies with age, country, sex, race, ethnicity, occupation, environment, and other factors.Variability in testing and data collection methods makes comparisons of prevalence and progression difficult.
In some areas, such as Japan, Singapore and Taiwan, up to 44% of the adult population is myopic.
A recent study involving first-year undergraduate students in the United Kingdom found that 50% of British whites and 53.4% of British Asians were myopic.
In Australia, the overall prevalence of myopia (worse than −0.50 diopters) has been estimated to be 77%.In one recent study, less than 1 in 10 (8.4%) Australian children between the ages of 4 and 12 were found to have myopia greater than −0.50 diopters. A recent review found that 16.4% of Australians aged 40 or over have at least −1.00 diopters of myopia and 2.5% have at least −5.00 diopters.
In Brazil , a 2005 study estimated that 6.4% of Brazilians between the ages of 12 and 59 had −1.00 diopter or myopia or more, compared with 2.7% of the indigenous people in northwestern Brazil.Another found nearly 1 in 8 (13.3%) of the students in one city were myopic.
In Greece, the prevalence of myopia among 15 to 18 year old students was found to be 36.8%.
In India, the prevalence of myopia in the general population has been reported to be only 6.9%.
A recent review found that 26.6% of Western Europeans aged 40 or over have at least −1.00 diopters of myopia and 4.6% have at least −5.00 diopters.
In the United States, the prevalence of myopia has been estimated at 20%.Nearly 1 in 10 (9.2%) American children between the ages of 5 and 17 have myopia. Approximately 25% of Americans between the ages of 12 and 54 have the condition. A recent review found that 25.4% of Americans aged 40 or over have at least −1.00 diopters of myopia and 4.5% have at least −5.00 diopters.
A study of Jordanian adults aged 17 to 40 found that over half (53.7%) were myopic."

High Degree Myopia

"Around 5 million British people are short sighted and some 200,000 of them will have high degree myopia. In a few people, high degree myopia might cause retinal damage or detachment. It may be associated with cataract and glaucoma.

High degree or chronic degenerative myopia can run in families and it might be advisable to discuss this with your medical advisors."

Orthokeratology

"Ortho-keratology, or Ortho-K, is the use of specially designed rigid gas-permeable (RGP) contact lenses to alter the shape of the cornea in order to reduce or correct myopia (short-sight). It can also be effective with low degrees of astigmatism.
According to the British Orthokeratology Society the procedure works best for people who are short sighted up to about –5D of myopia with no more than –1.50D of astigmatism.
To see if you fall within these categories look at your most recent spectacle prescription. If the ‘Sph’ box is –5.00 or less and the ‘Cyl’ box is –1.50 or less you may be suitable for orthokeratology and if you are interested we recommend that you consult your optometrist to discuss this procedure. Even if you are within these prescriptions, some people are more successful with orthokeratology than others.
If you are long sighted (up to +3 D) or more short sighted (up to –10D) you may be suitable for orthokeratology but this will be more complex than for the prescriptions above.
If you are over the age of about 45 and need bifocals/varifocals or a separate prescription for reading (or take your spectacles off to read) you must realise that if orthokeratology is done in both eyes this will affect your reading prescription too. If you are treated so you are not short sighted for distance and you would previously have removed your distance spectacles to read you will find that when your short sight is treated you will need to wear reading spectacles instead. You may find that this is more inconvenient than simply removing your spectacles to read. Your optometrist will advise you about this in more detail, and one of the advantages of orthokeratology is that it is reversible, so if you don’t like the effect you can return to the status quo"

Researchers test treatment for short-sighted kids.

"Researchers at the University of New South Wales are running a trial of special contact lenses that they hope will be able to correct short-sightedness in children.
The treatment, known as orthokeratology, is used widely in Asia.
Associate Professor Helen Swarbrick says there is compelling new evidence that the lenses can do more than simply correct short-sightedness.
'The excitement in this new research is that if we use these lenses in children we might be able to slow down or stop the short-sightedness,' she said.
Associate Professor Swarbrick explains how they are used.
'The lenses are worn overnight during sleep. During sleep they reshape the front of the eye,' she said.
'Then in the morning the patient can remove the lenses and see clearly all day without contact lenses.'
Unlike day time lenses, these are made of a hard plastic which shapes the cornea.
The treatment is widely used in Asia, where up to 85 per cent of people are myopic."

Eye correction is seriously short sighted - 20 November 2002 - New Scientist

"Yet the only proof that it works comes from a study of just 33 Japanese children in 1965, and from studies on chicks in the 1990s. And these studies have since been attacked as lacking rigour or relevance. In their trial, O'Leary and his colleagues at the National University of Malaysia in Kuala Lumpur, undercorrected the sight of half the children and fully corrected the rest. Then they measured the length of the eyeball with ultrasound every six months. To their surprise, they found that the eyeball elongates faster when vision is undercorrected. As a result, the team reports in a paper that will appear in Vision Research, on average the vision of the 47 children with undercorrected myopia deteriorated more rapidly than those given full correction. Yet full correction has long been out of fashion. 'I had to go back to 1938 to find someone in the literature saying a full correction should be made,' O'Leary says. The explanation for his results, O'Leary speculates, is that the eye cannot tell whether the focal point is in front of the retina or behind it. It just grows backwards if the image is out of focus - which means that not wearing glasses might be even worse than undercorrection. 'Any blurred vision will make myopia worse,' he says."

Eye correction is seriously short sighted - 20 November 2002 - New Scientist

"There is still much debate about the causes of myopia, but it is certainly common in children who spend a lot of time reading or doing close work. It has reached epidemic proportions in Far Eastern countries such as Taiwan, Singapore and Hong Kong, where 90 per cent of young people are short-sighted, compared with 15 to 30 per cent in Europe and the US."

Eye correction is seriously short sighted

The following Study is a real eye opener. Prof. Dan O'leary was my lecturer in anatomy when i was at university. He's widely regarded as one of the leading authorities in Myopia (short sightedness) and takes a very keen interest in this...Have a read...

"Millions of people worldwide may have worse eyesight and even be more likely to go blind because of a long-held but misguided idea about how to correct short-sightedness. A study intended to confirm the theory has instead been stopped because the children's eyesight was getting worse, New Scientist has learned. For decades, many optometrists have been routinely 'undercorrecting' short-sightedness, or myopia, when prescribing glasses or contact lenses. 'What was done was done with the best of intentions,' says optometrist Daniel O'Leary of Anglia Polytechnic University in Cambridge, England. Indeed, his study of 94 children in Malaysia sought to prove the value of undercorrection. Instead, it showed the opposite. While the number of children involved was small, amazingly it is the largest and most rigorous study to date. 'The study was meant to run for three years but after two years, when we found out we were making the children's eyes worse, we had to stop it prematurely,' O'Leary says. 'Short-sighted people need to know it's not the thing to do.' The results have been hailed by some optometrists as key evidence that could change the way children are treated. 'It's the strongest evidence I've seen in this field,' says Paul Adler, a spokesman for Britain's College of Optometrists. "It could change prescribing practice worldwide."