Posts Tagged ‘double vision’

Life in 3D

Friday, March 4th, 2011

Technology moves at a swift pace, and from the early days of wonky plastic specs and magic eye pictures, we’ve come a long way in making 3D an important part of our daily entertainment. From the ground breaking spectacle that was Avatar, to the joy of Toy Story 3, 3D is gathering pace and fans! It’s not all excitement though – there have been some concerns raised over the safety of 3D, and potential problems with eyesight, so studies are ongoing within our profession to monitor any effects.

So far, you can rest assured that there is no evidence to suggest that 3D can cause long term harm to viewers. They may even have a positive effect in bringing to light slight visual problems that the patient has been suffering with but have not been diagnosed. If you watch 3D and suffer any visual problems or headaches then it may prompt a visit to the optician, where double vision or undetected short or long sightedness can be corrected. These ‘eye-strain’ type symptoms have been reported by viewers, but it’s usually a short term problem.

Varifocal Glasses

The launch of the Nintendo 3DS portable gaming system has worried many parents, concerned over possible damage to children’s sight. The advice at present is that again, there’s no evidence to suggest problems. Parents should however note that like any other system children should not use them excessively. Hand held consoles are closer to the eye than 3D TV or film, and kids may watch them for longer, so frequent breaks are advised. The short focal distance to the screen of a game means the child has to focus harder, so eye-strain is a potential problem. Healthy outdoor sports, where you focus far away help the eye’s optical systems to develop properly, so a mixture of hobbies is the best way to offset any potential overuse of hand held games.

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Muscle Power

Wednesday, July 21st, 2010

When we really think about how the human body works, muscles are seen as the power stores that drive us. Think of muscles and we visualize hard bodied sport’s men and women with sculpted bodies, perfect specimens of fitness and health. There are however some tiny muscles that most of us take for granted, which we use every waking moment in our visual system. They work tirelessly throughout the day to make our eyes work together and give us the gift of sight.

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!

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All Greek To Me

Monday, July 13th, 2009

Sitting in the optician’s chair, bedazzled by the bright lights and blind without your glasses on, having an eye test can be a confusing experience. After the exam, the optician gives you your prescription – the power you need for corrective specs. So do you understand it? Read on for some simple explanations of what the numbers mean.

The first part says sph or sphere, and this tells you whether you are long sighted – it has a plus sign, or short sighted – it has a minus sign. It increases in steps of 0.25, and the higher the number, the stronger your lenses. If this says plano, or has the Greek symbol alpha in it, then you have no power here.

If the cyl or cylinder bit is filled in, you have an astigmatism. This is a common eye defect, and simply means that your eye is shaped more like a rugby ball than a football. Axis tells us which angle the cyl power needs to oriented to.

If you have any prism power, this corrects double vision. This may make your lenses a little thicker. The higher that any of the powers – sph, cyl, or prism are – then the stronger, and therefore thicker your lens will be.

If you need help for close work, then the reading section will be filled in, or will have a single power written across it – something like Add +1.50. This tells us what we need to add to your distance power to help you to see for reading.

Some opticians also write down your VA or visual acuity, this is how well you can see. It looks like a fraction. If it says 6/6 you have prefect vision, so well done you!

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