Posts Tagged ‘retina’

All About the Retina

Thursday, September 23rd, 2010

The retina is an amazing part of the eye that like most of our body parts, we don’t appreciate until there are problems with it! For those of you who don’t know, it’s a light sensitive layer of tissue that lines the inside surface of the eye. Think of the retina as the film in a camera – light enters the eye, reaches the retina and is transmitted to the brain via nerve impulses, and our brain then interprets the image.

The retina is made up of layers of neurons joined by synapses. They contain photoreceptor cells that allow us to distinguish light, dark and colour. Photoreceptor cells give us our reflex reaction in bright light., rod cells work in low light and give us shades of grey vision at night, cones work during the day and allow us to see colour. It’s the lack of certain cone cells that leads to being colour blind. Each retina has about 7million cones and 75 – 150 million rods.

Retinal detachment is the commonest retinal problem, and can happen due to a blow to the head, or as a result of the retina being stretched if you’re very short sighted. If the retina tears it will come away from the underlying layers. The early symptoms are the appearance of lots of floaters in the eye, or flashing lights, or loss of part or all of the visual field in one eye. This is an emergency, and if you notice any of these symptoms you should go straight to your GP, Optician or A&E. Treatment involves surgery to re-attach the retina, and is usually sight saving if done quickly enough.

The macula is a tiny area of the central retina which is highly pigmented and gives us the middle of our visual field and fine detail. Macular degeneration can lead to loss of vision and usually affects adults over the age of fifty. There are two types of the disease, wet and dry. The wet form is sudden and severe, when blood vessels grow behind the retina and lead to detachment. Urgent laser surgery is needed to save the retina. The dry form occurs slowly, call debris builds up behind the retina and damages and detaches it. At present preventative treatment in the form of UV protection and vitamin supplements is the best treatment.

Swift action is the key to retinal problems, so at the first sign of anything unusual with your sight, seek help immediately.

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General Health Precautions Benefit Eye Health

Tuesday, September 7th, 2010

Age Related Macular Degeneration is the leading cause of sight loss in the Western world, and research is increasingly discovering that we can all reduce our risk factors with a few precautions that make sense to help general health too. As our population ages diseases due to us ‘wearing out’ are increasing, and ARMD is an example of this. A lifetime of exposure to pollutants, UV light, and a diet lacking in essential nutrients can lead to retinal damage and loss of sight.

Protecting the retina is vital, so we should all wear UV filtering specs, on clear or tinted lenses when we’re outdoors. Interestingly, less people seem to wear specs on the beach than in parks, but note that more light is reflected back from sand and water than any other surface. This is important for children, who are likely to spend more time outdoors, and have less natural protection in the inner structures of the eye. This allows more UV inside the eye, reaching the vulnerable retina. Sunglasses are cool, so persuading kids to wear them should be easy! Make sure they fit comfortably and conform to EU safety standards for full UV protection. Wide brimmed hats will also help to screen the eyes.

The five a day we’re all meant to eat protect your retina along with all the other health benefits it brings in terms of reducing the likelihood of Colon and other cancers. Aim for a range of coloured vegetables, with the emphasis on the green and leafy! Carrots, tomatoes, parsley and blueberries are all excellent too, and supplements containing Lutein and Zeathanthin will help you to maintain high levels of pigment in your retina. Macular pigment filters out the harmful blue light which causes the damage.

Moderate exercise, taken daily, will benefit general health and your sight. Oxygen circulating in the blood stream benefits the eyes too, and arthosclerosis has been cited as a risk factor in ARMD. Give up smoking now! It’s a pollutant that affects the retina as well as every other organ in the body! Keep an eye on your blood pressure, and take your GPs advice if you’re told you need to lower it. Systematic hypertension has been proven as another risk factor to ARMD.

So without sounding like the nanny state, it makes sense that if we can help our eye health along with our general health, that’s more benefits for the same amount of effort – win win!

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The Perfect System

Sunday, June 20th, 2010

The eye is one of the most amazing organs in our bodies. Our sight is the most precious of our senses, and these small and perfect globes make sight happen by refracting light through it’s systems to help us make sense of our world. The eye is an incredibly complex and sensitive structure, all finely tuned, so it’s not surprising that tiny abnormalities result in visual defects and lead us to need help to correct our sight.

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.


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Diabetic Danger

Monday, April 12th, 2010

We are all aware that the so called ‘obesity epidemic’ is a growing cause of concern  to our future health. One of the problems associated with this is the rise in Diabetes, a complex disease that causes a wide array of symptoms and potential problems for sufferers. As Opticians we spend a great deal of time with Diabetic patients, as the effect on sight can be devastating.

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.

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To Wear or Not to Wear?

Wednesday, March 24th, 2010

A common question that we’re asked is one that may seem to have an obvious answer. If I wear my glasses, will it make my eyes weaker? Will I start to rely on them? Some patients are clearly so concerned that they put themselves at risk by leaving their specs off unless they absolutely have to wear them.

So, why do we need glasses and how do they work? Put simply, you are short sighted if your eyeball is too long, and long sighted if it’s too short. Light is focused in front or behind the retina and your sight is blurred. Some visual defects are also down to irregularities in the surface of the Cornea, the clear area we look through at the front of the eye.

So, as the reason for your sight defect is physical, wearing glasses or leaving them off will not change your sight. All that happens is that your brain realises that life is easier with the specs on, and you get used to seeing clearly. This makes you feel reliant on them, but if you left them off for a day or two this effect would be lost.

At best you’ll get a headache if you don’t wear them, which will quickly improve once you put your glasses back on. At worst you could cause an accident by not seeing clearly and failing to react. Never drive without your specs if you’ve been told you need them to reach the driving standard.

Keeping your glasses on your face, where they belong, will keep the frame in good condition, and save any eye strain. They’ll always be there when you need them, and you’re utilising the gift of sight at it’s maximum standard. The good news is that leaving them off will not make your sight worse, so don’t panic if you do feel more comfortable under some circumstances without them on, it is allowed as long as you’re not behind the wheel!

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Eye Health Breakthroughs

Thursday, March 4th, 2010

Some exciting eye health advances have hit the news within the past couple of weeks, with a couple of surprising ways to protect your sight!

Researchers at the Hong Kong Eye Hospital have found the Green tea could help in the prevention of the eye disease Glaucoma. Glaucoma leads to loss of peripheral vision due to excess production or inadequate drainage of fluid within the eye. This leads to an increase in pressure within the eyeball, which damages the Optic nerve. The study examined Rat’s eyes, where it was found that catechins, active constituents in green tea, are absorbed by the eye. This helped to protect against oxidation, the cause of some eye diseases.

A test that can be purchased and used at home can help patients to find out their risk of Age Related Macular Degeneration. This eye disease leads to loss of central vision and fine detail. The kit uses a small saliva sample for analysis, which is then checked and a full report issued. A free counselling service is also offered, with suggestions to protect against and prevent ARMD.

For sufferers of ARMD, research has proven that Saffron can reverse the disease. Saffron is a spice used as a colouring in Spanish and Indian cuisine, which derives from Crocus Savitus flowers. Pound for pound it can cost more than Gold, due to the vast quantities of delicate filaments needed to make a pound of Saffron. It is a well known anti-oxidant and is presently used to treat cancer and depression. It encourages oxygen flow, and in the eye affects fat storage to make the cells of the retina more resilient to damage. Patients on the trial showed a reversal of symptoms while taking the Saffron, and researchers are now working on finding the optimum dosage.

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All About Eye Tests

Friday, July 17th, 2009

If your eye sight is not up to the driving standard then you might be more dangerous than a drunk driver when out on the road. An eye test will detect eye diseases and pick up general health problems too. 89% of people fear the loss of their sight over any other sense, yet many do not have regular eye tests.

In the UK your eyes will be tested by an Optometrist – also called an ophthalmic optician. They are fully qualified, and are governed by the General Optical Council, who insist upon a specified list of tests, and control other issues such as the confidentiality of your appointment. The GOC suggest that eye exams are necessary every two years, although you may be recalled earlier if anything needs monitoring. The opticians will fully check the health of your eyes, and test your vision.

Eye Examination Routine

The optician will talk to you about any medication you are taking, your general health, and any symptoms you are concerned about. They will ask about your job, hobbies and sports activities, as these may affect the glasses they prescribe. They will assess the glasses you currently wear. You will then be tested in the following ways.

Intraocular Pressure

High pressure of the fluid inside the eye could mean Glaucoma, an eye disease that can lead to blindness. Nowadays most Opticians use a puff of air to read the pressure.

Visual Fields

A symptom of Glaucoma is a reduced field of view. The optician will check your peripheral vision, and your all-round vision.

Retinal Imaging

The optician uses a camera to take a picture of the retina, the light sensitive layer that lines the back of the eye. This can detect early signs of eye disease. During the rest of the test the optician sees small areas of the retina, with imagining they can see all of it and store the image for future reference.

Refraction

This tests your need for corrective lenses. You are checked for close work, intermediate – ie the VDU, and far distance. The optician uses a trial frame, into which he puts a series of test lenses, or a mechanised version called a phoropter. He may also use a hand held light to double check your prescription.

Pupil Reflex

This checks that your pupils react normally to light. Abnormal responses may be a sign of a neurological problem. The optician shines a light into your eyes to make sure your pupils dilate and contract as they should.

Oculomotor Balance

Muscles controlling eye movements have to co-ordinate, to give you comfortable vision and no double vision. There are several different ways of checking this.

Ophthalmoscopy – This is very important as it can detect eye health problems and general health issues such as high blood pressure, diabetes and macular degeneration. The optician uses a hand held instrument to examine the internal structures of the eye.

The optician will explain your results, and give you a copy of your spectacle prescription. In the event of finding any general or eye health problems that need treatment or investigation they will go through this with you and refer you to your GP.

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See Your Hundredth Birthday!

Sunday, May 17th, 2009

Even if you’re a fitness freak or a gym bunny, the one aspect of health you may not have thought about is looking after your eyes. We all focus on a balanced diet, moderate exercise, and looking after ourselves, but do we pay attention to one of the most important organs in our bodies?

Keeping your eyes healthy is really a matter of prevention, and a few simple steps can go a long way towards preserving your sight and general ocular (eye) health. A vital step is to have regular check ups with a qualified Optician, also called an Optometrist. They recommend tests every two years to check your eye health, tell you if you need glasses, and will even pick up some general health issues too.

If you smoke – give up! Smoking is a factor in the eye disease Macular Degeneration, and as soon as you stop you are halting any damage. Macular Degeneration causes loss of central vision, which means you won’t be able to see to read or drive. It may also be a factor in formation of cataracts.

A good balanced diet will obviously help your general health, but can also maintain healthy eyes and vision too. Natural carteniods, found in green leafy vegetables have a positive effect on the retina and therefore protect against Macular problems. If you don’t eat a wide variety of fruit and vegetables you might consider taking a supplement to maintain eye health.

There are many supplements on the market. Ingredients to look for are antioxidants, zinc, selenium, Vitamins A, B, C, and E, Lutein and Zeaxanthin. Antioxidants and zinc reduce the risk of Macular Degeneration. Selenium and the Antioxidant vitamins A C and E encourage mucus production, which keeps the soft tissue around the eye – the conjunctiva healthy. Vitamin C may also protect the eyes against cataract formation. Vitamin B complex is vital to healthy function of the Optic nerve. Lutein and Zeaxanthin occur naturally in the retina, the light sensitive layer that lines the back of the eye. These nutrients protect the retina by absorbing blue light, which can damage the Retina.

You may not have realised that keeping your body fit keeps eyes fit too. It improves oxygen levels in the eyes, and a recent study has shown that children who play outside and therefore focus at long distances are less likely to become myopic (short sighted) They also benefit from being out in natural light too.

If you wear prescription glasses then take good care of them and ensure that they are kept clean and up to date. Talk to the Dispensing Optician when you visit your Optician’s practice to make sure that you have UV protection if necessary, and the correct tints for your needs. They will also help you with protective glasses for sport or at work.

Looking after your eyes takes very little but reaps huge rewards. We’re all living for longer – won’t it be nice to actually see the cake at your hundredth birthday party?!

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UV and Your Eyes

Saturday, May 16th, 2009

What Is UV Light?

UV or Ultra Violet light is an invisible part of the spectrum of light that surrounds us. Due to the increased incidence in skin cancers, we know about the damaging affect of UV on our skin, but do we think about the fact that UV can also damage our eyes?

UV is made up of three wavelengths of light

  • UVA- closest to visible light, range 320 – 400 nanometers
  • UVB – 280 – 320 nm
  • UVC – 280 – 200 nm

Could UV Damage My Eyes?

UVA and UVB can cause significant damage to the crystalline lens inside the eye and to the retina. It’s also harmful to the cornea – the transparent window at the front of the eye.

UVA is the most dangerous, especially if you are exposed to low doses over a long time. It can damage the eye but it is absorbed by the crystalline lens. This protects the retina but as the affects accumulate pigments are generated within the lens, and with ageing and further exposure cataracts develop. When cataracts are surgically removed that vital filter to protect the retina is gone.

UVB causes sunburn and snow blindness, and this is exacerbated by reflection from water and snow. The cornea absorbs it to protect the internal structures of the eye, but that does leave the cornea vulnerable to problems. Pterygium is a patch of cloudy tissue that grows on the cornea as a result.

UVC is filtered out by the ozone layer, but if you’re in an area where the ozone layer is thin, then it may still be dangerous.

Do I Need UV Protection?

Yes, if any of the following applies to you:

  1. You spend time on the water.
  2. You’ve had cataracts removed.
  3. You spend most of your time outdoors.
  4. You like wearing dark glasses.
  5. You’re regularly exposed to UV light.
  6. You live where the ozone layer is thin.

What Will Protect My Eyes?

Wearing spectacles, whether dark or clear gives you some protection against UV, but total protection only comes from a UV Filter or a Polycarbonate Lens. Other lens materials give varying degrees of UV protection.

Standard Plastic – As these lenses can yellow over time manufacturers add a small amount of UV filter to the material. They give about 92% UV protection.

Glass – As they do not absorb any UV they give no protection.

Lenses that darken in the sun – these lenses go dark due to UV light, so as they change they block all UV.

UV filter – This is a lens coating which guarantees to give 100% protection against all types of UV.

Sunglasses are sometimes labelled as giving protection against UVA, UVB, or UVC. The problem with listing these categories is that we see the UV symbol and assume we are protected. You need to make sure that the lenses in question filter all types of UV.

Do I Need A UV Filter On Sunglasses?

Our eyes react to bright light by reducing the size of the pupil. This stops light from getting to the retina and the lens. So a tinted lens will let light flood into the eye, and without a UV filter the internal structures are fully exposed to the dangers of UV.

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