So here’s the history lesson – glass photochromic lenses appeared in the mid-sixties. They had a light tint when you were indoors, and then went dark when you stepped outside – how cool is that?! UV in sunlight triggered the change. The only disadvantage was that as they were glass, as all lenses were in those days, they were heavy, and of course could break if dropped. The lenses were slower to react than our modern versions, and over time, stayed darker in all light conditions. In 1986, the first plastic photochromic lens arrived, giving safer, lighter weight photochromics. The glass versions had been available in several different colour options, but these new fangled plastics came in light brown which then darkened to blue – choosing a matching frame was a challenge!

Now here’s the science lesson – the lenses work thanks to colourless molecules within the material that are excited by UV radiation. This breaks a chemical bond within the molecules, and they go dark! They fade back when the UV stimulus disappears, and you go back indoors.

Finally, here’s the practical lesson – what can these lenses do for you? Well, if you like one pair of specs for everything, photochromics give you clear lenses and sunglasses all in one. You don’t have to swap glasses around, and you only need to carry one pair with you, whatever the weather. Since 1986 several new versions of the material have been developed, and thankfully they are now available in grey or brown. Each new generation of lenses are faster reacting too.

So if you wear photochromics, or may choose them next time, take a moment to appreciate these quietly hard working, amazing lenses. That’s all for today’s lesson – class dismissed!

Varifocal Glasses

The thickness of your finished lenses depends on several factors. The strength of your lenses, the size of your chosen frame, and even the distance between your pupils all affect the lens thickness and weight, and where any chunky edges will show. If you are short sighted, your lenses will be as thin as physically possible in the centre, and thicker towards the edge. If you are long sighted, they will be thick at the centre, and will magnify your eyes, but the edges will be relatively thin.

Once your prescription gets above -4.00, or +2.00, you have to start being careful with your frame and lens choice. If you are petite, and your eyes are close together, choose a small rather than a larger frame, and choose a thinner material lens. These lenses are made of a dense material, that gives you the required lens power but with less bulk. Most modern lenses in high density materials are also made in a super-clever flat form nowadays, so they are less bulbous as well as thinner.

If you think your specs are too thick and heavy, contact us with your frame choice, and we’ll calculate the end result of your lenses. If a high density lens will reduce lens thickness your specs will look better, be more comfortable, and even give you sharper vision. Thicker lenses give increased internal reflection, which can interfere with your sight. Weight loss without the help of the gym or a celery stick – what more could you want!

Varifocal Glasses

Generally the eye is long or short sighted because the eyeball is the wrong length, so light doesn’t focus correctly on the retina, and your sight is blurred. Astigmatism arises because the curve of the eye is not even. You need help for reading because of unavoidable ageing changes within the eye. So don’t worry that you can accelerate your sight defect or indeed make your eyes better if you don’t wear your glasses.  Computers are also blamed for causing eye strain and making the eyes worse. In reality, you just notice a sight defect more if your eyes are tired, and constantly staring at the screen means your eyes feel slightly blurry when you look away. So is there any way that you can improve your own eye health?

Having an eye test every two years, or more often if your optician recommends it, will ensure that your eyes stay as healthy as possible and that any eye health problems are picked up from the earliest signs. Keeping your specs prescription up to date and wearing glasses as prescribed will save eye strain and keep the dreaded headaches at bay. Make an effort to blink regularly if you’re in front of a screen all day and glance across the room whenever you think about it to allow the eye to change focus. Gentle daily exercise increases oxygen levels in the eye, essential for healthy tissues.

If you wear contact lenses be strict with sticking to check ups and using the solutions your Optician suggests. Don’t exceed wearing time and if you buy them from the internet take care to buy exactly what your Optician recommends and make sure you order from an up to date prescription.

Varifocal Glasses

We have two eyes that work together to form one image for many reasons. The two slightly differing images from each eye fuse to let us see clearly and to give us perception of depth. Two eyes also give us a wider field of vision, and allowed our ancestors to see predators creeping up along side us! Of course having two eyes also means you have a back up if one goes wrong!

Babies are born with the basic tools to acquire binocular vision – they have two eyes placed at the front of the head that each creates an image of similar size and quality. The visual pathways then run from the eye to the brain to allow us to interpret what we see. Babies don’t immediately have binocular vision however, this develops between three and five months as they take in their surroundings and are stimulated by what they see. It continues to develop up to age eight.

Glasses Online

If anything stops the visual stimulation – like a turn in one eye that stops you seeing clearly – then the pathways don’t develop. After age eight, there’s nothing that can be done to develop the necessary pathways, and sight will be affected in that eye. In later life, accident or illness such as stroke can cause loss of sight in one eye, or stop the eyes from working together. This can lead to you feeling disorientated, unsure of distances, and generally unsteady while walking about or driving.

If sight is permanently lost in one eye, adjustment will take time, but mostly people adapt, turning their head more to compensate for the loss of peripheral vision. Judging depth with one eye is a skill that you acquire. If there is sight in both eyes but they no longer work together properly, then we can build prisms into your spectacle lenses to help you fuse images together. This works well in the majority of cases, although it can’t be done with contact lenses.

The first thing is to make sure your spectacle prescription is fully up to date. A change in lens power that your optician said was borderline may make a difference when light levels are low. Scratched or damaged lenses or coatings may all interfere with your vision. A new, sharp and clear lens may make a radical difference to your comfort and confidence at night. So if you didn’t change your glasses last time, or didn’t think you needed to, check with your optician as to any improvements that could be made. Make sure your prescription is up to date – was your test within the last two years, or whatever time scale your optician recommended.

Secondly, don’t wear any kind of tinted lens for night driving, for some people even the very lightest tint can impair their vision. Photocromic lenses which change in the sun always have some residual tint, and this gets darker over the life span of the lenses. You may need to invest in a clear pair specifically for night driving.

Thirdly, an anti-reflection layer will help. Light is reflected by the front and back surface of your windscreen, your lenses, and mirrors. Every reflection cuts down on clarity and dazzle from oncoming vehicles is at best uncomfortable, at worst dangerous as you are momentarily blinded. The coating makes sight sharper, cuts out interference, and damps down dazzle – it’s useful to know there’s’ one car coming towards you, not two!

So stay and comfortable on the roads this Winter, with a little thought and care and possibly the investment of some new specs.

The movement of each eye ball is controlled by six muscles, called extra ocular muscles, which hold the eye in place and enable it to move. This gives us the maximum vision all around us, and helps both eyes to work together. Shut each eye individually and you’ll realize that you see a slightly different image with each eye, but by controlling the movements of both eyes and the brain then fusing the two images together, most of us don’t suffer from double vision.

Problems arise if your muscles don’t work together, and the eyes don’t turn together. Injury or disease such as stroke can cause difficulties with this, stopping the two eyes from co-ordinating their movements. Some of us are born with abnormalities in the length of a muscle, which means one eye is out of alignment. This can be corrected by surgery.

Opticians correct double vision by using a prism built into your spectacle lenses. The prism bends the light so that you only see one image. This can be put into one or both lenses, and usually we divide the prism up so that the weight is even across both lenses. We also use prisms that stick onto lenses sometimes, this allows us and you to experiment with the amount of prism needed, or correct a temporary problem. When you’re tired the double vision can be worse, as your eye muscles suffer from fatigue just like aching legs or arms! To prevent eye strain and overworking those busy eye muscles, always wear glasses if they have been prescribed, take breaks from close work at regular intervals, and visit your optician at once if you suddenly suffer from double vision. All less tiring than a visit to the gym!

One of the most common problems patients suffer from is lazy eye, or  as people often call it. One eye wanders and does not focus as with as normal eye. This can make it difficult for other people to tell where you are looking. It can be successfully operated on, so do bring it up with your optician, it may be possible for you to be referred to the hospital eye service for assessment.

Cosmetic problems with the coloured part of the eye, the Iris, are more unusual. We have patients with different coloured eyes, or with a segment of the Iris missing. This can be treated with coloured contact lenses, which we can use to match the different colours, or to disguise a gap in the Iris. This can produce excellent results without resorting to surgery.

Ptosis is a term which covers drooping lids due to muscle defects. The muscles which control the eyelids are a complex mechanism and any difficulties with the system can impair vision if the lids droop down across the eye. Surgery can help in some cases, or you can have a slim metal prop attached to your specs which lifts the faulty lid.

Any of these issues may also be helped when it comes to changing your specs – small and fashionable frames, possibly with a light tint will give your more confidence and a small measure of camouflage. It’s never to late to look into solutions for these problems, and new techniques may give you options now that weren’t possible a few

For perfect sight, light has to enter the eye and focus on the back surface. If your eyeball is too long, you’ll be short sighted. If it’s too short, you’ll be long sighted. Specs or contact lenses position the light in the right place so you can see clearly. If the curve of your cornea, the clear window at the front of the eye, is imperfect, then this will also create a problem with focussing.

Light enters the eye through the pupil, the black hole at the centre of the eye. It travels through the crystalline lens, a transparent structure that changes shape to let us see both close up and far away. Muscles hold the lens in place and stretch and relax to alter its shape and therefore its focus. If the lens is not the perfect size and shape then this will add to the visual defect of the eye. So you can see that there are several reasons why you may need glasses or contact lenses.

Once your optical system has been corrected and is working as it should, light reaches the light sensitive layer, the Retina, which lines the back of the eye. Here the image we see is upside down and in reverse! It travels to the brain through the optic nerve, where thankfully it’s put the right way round.

Ophthalmologists and opticians are lucky in that they’re the only clinicians who can examine their specialist organ without cutting their patient open! Thanks to ever advancing screening equipment and retinal imaging systems we can see inside your eyes and spot the very first signs of problems. This fantastic and beautiful system works on our behalf for every minute of our waking day, so look after it by attending your check ups and taking a few minutes to appreciate and maintain it.

An eye is short sighted because the eyeball, from back to front, is the wrong length, and light isn’t focussed correctly, so what we see is blurred. Specs and contact lenses re-focus the light so that if falls in the correct place and we see clearly. Laser surgery works by altering the curve of the front of the eye, so that light is focussed properly, but it’s a pretty drastic solution!

The Australian researchers have been working on spectacle lenses which play with peripheral vision. (That’s what we see around the edges!) They are working on creating lenses that work differently to standard spectacle lenses to control our short sightedness and stop it progressing. There have been many suggestions through the years to alter the length of the eye, and to understand why myopia occurs. The social stigma of wearing glasses and the sheer inconvenience of specs will always drive us forward in trying to correct visual defects by more permanent methods. There are already techniques such Orthokeratology, where you wear specially prescribed contact lenses at night to reverse myopia.

So even if we’re presently hanging onto our specs and contact lenses, there may be hope for the future, if the researchers are far sighted enough!

Diabetic retinopathy is a major cause of blindness, and the condition must be carefully monitored and quickly treated to save a patient’s sight. Uncontrolled Diabetes causes blood vessels to grow and leak into the retina, destroying this vital layer of cells and leading to loss of sight. Research is currently involved in better retinal screening, improved treatment uptake, and new treatments. If the early signs of retinopathy are treated quickly by laser surgery sight can be saved.

At present we know that tight control of sugar levels in the first few years of diagnosis can affect development of Diabetic retinopathy in the future. Controlling blood pressure and cholesterol lower blood sugars, and therefore help to reduce symptoms. Patients taking Statins to control their cholesterol have a lower incidence of Diabetic Retinopathy, so it’s interesting that all the symptoms and good management are interlinked in combating the disease. As Diabetic Retinopathy is also connected to memory impairment and reduced brain function it really does make sense to take a holistic approach to managing Diabetes and controlling sugar levels.

Yearly eye exams are free to diabetic patients, so take advantage of this and make sure you have your check ups. Find an optician with OCT screening equipment – this takes a 3D scan of the retina and will pick up the every earliest signs of problems. Manage your symptoms and don’t mess with those sugar levels – as well as endangering your life and your sight here and now, you could be storing up problems for the future.