May/June 2018 Newsletter
TWO EYES ONE IMAGE
The human visual system is a complex network including the eyes, the ocular nerves, and specific areas in the brain that process visual information. Because the eyes are side by side on the face, they see slightly different images of the same object, or the same object from slightly different perspectives, although the images overlap to some extent. These are transmitted via the optic nerve to the brain which synthesises them to create a single visual image. This ability to converge information from both eyes is called binocular vision and is essential for three-dimensional (3D) or stereoscopic vision. It allows us to perceive depth and judge distances and relationships between objects. Without it the world around us would appear flat like a two-dimensional picture.
So many of the day to day activities we take for granted and perform without a second thought depend on stereoscopic vision. Pouring a glass of water, parking a car, threading a needle, walking up or down stairs, catching or hitting a ball, even reaching out to shake someone's hand would be more difficult and less accurate without our ability to judge depth. It would be impossible to pursue certain professions and challenging to play certain sports.
The eyes and the brain need to work together in order for us to experience the world in three dimensions. The eyes are responsible for receiving a clear focused image which the brain is required to process and interpret, helping us to make sense of what we see. Light bouncing off objects passes through the cornea, and the pupil expands or contracts to control the amount of light entering the eye. It then travels through the lens and finally focuses on the retina at the back of the eye, where it is converted to electrical impulses which are sent via the optic nerve to the brain. Having gone through other areas of the brain, the impulses end up in the visual cortex where the perception of the visual images occurs. Here the brain may rely on visual memory to assist in the interpretation of the visual stimulus it has received.
Unfortunately, not everyone has stereoscopic vision, or the ability to see in 3D. This always occurs in people with only one functional eye and can occur to some extent in people who have two eyes that do not work together effectively. Whether someone was born with one eye or has lost an eye for whatever reason, they will be unable to perceive depth because they are unable to see an object from two different angles.
Binocular vision problems are among the most common visual disorders. The symptoms may include headaches, eye strain, blurred vision, light-headedness, neck and shoulder discomfort and double vision. Some people experience difficulty with balance, particularly on getting up too quickly, motion sickness and sensitivity to glare. Others may feel insecure driving as they are sometimes unable to judge the speed or distance of oncoming cars. Reading problems associated with binocular vision problems include skipping lines or words while reading, losing the place frequently, comprehension difficulties and fatigue after reading. Many people with binocular vision problems report having poor coordination especially in sports which require catching or hitting a ball.
Fortunately, there are a number of treatment options for most cases of binocular dysfunction. Glasses with specially prescribed lenses, filters or prisms can help to correct eye alignment. A course of vision therapy to improve eye coordination and eye teaming is generally successful. In certain cases, surgery is necessary to realign the eyes, and this may be followed by a course of vision therapy and/or the prescription of glasses. Your optometrist will guide you towards making the most appropriate decisions in terms of treatment. As with most problems, the earlier the problem is diagnosed and managed, the more successful the outcome, especially during childhood while the visual system is developing.
While the eyes and brain perform 3D processing automatically, film makers work at using the same principle to create movies which make the audience feel that the scenes they are watching are happening right in front of them and they are part of the action. Just as our view of the world would be flat without stereoscopic vision, so too would all the movies we see appear two dimensional on a flat screen, but more and more 3D films are being produced giving us an alternative.
The first 3D film was made in 1922. Since then, with the technological advances over the years, 3D movies have become extremely sophisticated and hugely popular worldwide. There are several different types of 3D technology used today to achieve a 3D image on the screen. One of these uses two cameras to film two versions of the same image to mimic the exact angle as the eyes would see it. By wearing specially designed 3D glasses, the two images taken at slightly different angles come together in a single cohesive image. Depending upon the exact type of technology used, 3D glasses will either use special shutters, color filters, or polarised lenses to receive the images. As with human vision, the final process occurs in the brain.
CLEAR-EYED REASONS TO QUIT SMOKING
Every year, on 31 May, the World Health Organisation and partners mark World No Tobacco Day, highlighting the health and other risks associated with tobacco use, and advocating for effective policies to reduce tobacco consumption. As well as having a direct impact on eye health and quality of vision, tobacco use is one of the major risk factors for the development of coronary heart disease, stroke and peripheral vascular disease, all of which can affect the eyes.
The good news is that smoking is the most preventable cause of vision loss. Even someone with a long history of smoking can significantly reduce the risk of health complications by quitting. For example, giving up smoking reduces the risk of macular degeneration by six percent after just one year, and it also reduces the risk of developing cataracts.
The harmful effects of smoking on the eyes include:
- biological changes in the eyes that can lead to vision loss;
- damage to the delicate blood vessels in the eyes caused by tobacco chemicals;
- interference with the production of tears;
- decreased amount of oxygen and nutrients reaching the macula due to compromised blood flow;
- increase in the risk for age-related macular degeneration (AMD), a leading cause of irreversible vision loss;
- development of AMD up to 5 years earlier than non-smokers;
- increased risk of cataracts;
- increased risk of developing diabetic retinopathy, damage to the blood vessels of the eye;
- risk of faster progression of diabetic retinopathy;
- increased risk of dry eye syndrome, a cause of eye irritation in elderly people;
- increased risk of developing thyroid eye disease;
- increased prevalence of colour vision deficiency;
- risk twice as high as normal to develop uveitis.
As well as its impact on the eye health of smokers, smoking affects those around them, so-called passive smokers, increasing their risk of developing certain eye conditions which could lead to vision loss and compromised quality of vision.
It is not all doom and gloom! Research indicates that stopping smoking improves the chances of avoiding certain eye diseases and slowing down the progression of others, and the risks tend to decrease the longer one has not smoked. If you are a smoker (or a quitter!) and notice changes in your vision, make an appointment to see your optometrist for a comprehensive eye examination. The sooner problems are detected the sooner they can be managed, and further deterioration prevented.
We have all experienced red or bloodshot eyes at one time or another. Eye redness occurs when the small blood vessels in the eye become dilated, inflamed and congested with blood. There are a number of causes of eye redness, most of which are not serious and do not require medical treatment, unless they persist or are accompanied by symptoms such as pain or changes in vision. The degree of redness is not usually related to the severity of the problem; red eyes sometimes look worse than they are!
Common Causes of Eye Redness
These range from lack of sleep to allergies, from irritants in the air to infections, from trauma to the eye to chronic health conditions.
Deficiencies in certain vitamins and amino acids, sensitivity to some foods and excessive alcohol consumption are often reflected in red eyes. Allergies to cosmetic products or not removing make up before going to sleep can cause red eyes. General allergic reactions, for example to pollen or pets, are often accompanied by red, watery, irritated eyes, and the common cold often manifests with red watery eyes as well as a runny nose.
Environmental factors include dust, lengthy exposure to the sun, dry air and chemical fumes. Eye redness may occur only the day after exposure to these irritants. Prolonged hours in front of the computer can lead to eye fatigue and red eyes.
Contact lenses can prevent sufficient oxygen from reaching the cornea. If the lenses are worn for too long or worn while sleeping, they can cause redness, irritation, infections and in more serious cases corneal ulcers.
More specific causes of eye redness are bacterial or viral infections in different parts of the eye. These are typically accompanied by a discharge and pain or discomfort. They include inflammation of the follicles of the eyelashes (blepharitis), inflammation or infection of the membrane that covers the eye (conjunctivitis or "pink-eye"), ulcers on the cornea, and inflammation of the uvea (uveitis). One of the first signs of a sty is redness, along with sensitivity and a swelling or small red bump that appears on the eyelid.
Eye redness may be one of the symptoms associated with chronic health conditions such as diabetes, hypertension, and liver disease, as well as a side effect of long term medication used to treat certain conditions. Childhood illnesses, particularly measles, are usually accompanied by red eyes.
A small bright red blood blotch sometimes appears in one eye after exertion or even a strong cough or sneeze. This subconjunctival haemorrhage occurs when a blood vessel just under the surface of the eye breaks. It looks uncomfortable but is not serious unless accompanied by pain. It will usually clear within a week to 10 days. Trauma or injury to the eye will typically cause the eye to appear red. Even if it is not painful it should be checked by a doctor or optometrist to rule out serious damage.
Acute glaucoma is characterised by a sudden increase in eye pressure, red eyes and pain. In such cases, immediate medical intervention is crucial.
When should you contact your doctor or optometrist?
The majority of cases of eye redness do not warrant emergency medical attention, and often the symptoms disappear on their own or can be relieved by applying a cold or warm compress to the eyes. However, medical attention is advised if there has been trauma to the eyes, the symptoms last longer than two or three days, there is pain or discharge from the eyes, or there are changes in vision or sensitivity to light.
Red Eyes in Babies and Children
Puffy red eyes in babies and children are common, and as with adults may be due to a variety of factors. Generally, they are not serious and tend to resolve within a day or two but parents need to be alert to signs such as discharge and obvious discomfort or pain that would necessitate a visit to the doctor. Allergies to irritants such as pet dander, cigarette smoke and pollen are thought to be the primary cause of red eyes. They may be associated with other allergic reactions. In some babies a blocked tear duct prevents adequate drainage of tears, resulting in swollen, crusty, puffy eyes. A red lump on the edge of the eyelid could indicate a sty which is uncomfortable but will probably go away in a few days. Conjunctivitis (or "pink eye") is a common occurrence in children and is highly contagious, spreading from one child to another especially at school. Conjunctivitis in a newborn can be indicative of a more serious infection which needs to be treated by a doctor.
Gently bathing the eyes with cotton wool and warm water removes crusting and relieves discomfort. If the infection persists antibiotic eyedrops may be prescribed. A cool compress or even cucumber slices over the eyes will constrict blood vessels and reduce swelling and inflammation.
Red Eyes in the Elderly
As we get older, the normal function of eye tissue decreases and age-related eye problems are common. These include cataracts, age related macular degeneration, glaucoma, diabetic retinopathy and dry eye syndrome. Red eyes may also be the result of blepharitis, conjunctivitis, corneal ulcers, or allergies. Certain medications for chronic health conditions in the elderly may cause red eyes.
Help for Red Eyes
Bathing the eyes with cotton wool and warm water removes crusting and relieves discomfort. A cool compress or even cucumber slices over the eyes will reduce swelling and inflammation. Wash the hands frequently, encourage hand hygiene in children and discourage them from touching or rubbing itchy eyes as this spreads infection. Use separate towels for family members with eye infections. Speak to your optometrist about using preservative-free contact lens solutions. Specific eye drop products may provide temporary relief from symptoms of eye irritation, such as redness and dryness, but they sometimes exacerbate the problem. Ask your optometrist for guidance on these.
Red Eyes in Photos
Red eyes in photos has nothing to do with inflamed, tired or infected eyes!
The human eye is capable of adjusting to different light conditions. The amount of light that reaches the retina at the back of the eye is controlled by the pupil. On a bright sunny day, the pupil will contract, allowing only a small amount of light to enter the eyes, while at night, the pupil will enlarge in order to allow as much light in as possible. When the light from the camera flash goes off in a room with dim lighting, the pupils are dilated, and do not have time to contract fast enough to adjust to the bright flash of light. A large burst of light reaches the back of the eye, reflects back off retina with its rich blood supply, and that reflection is captured by the camera. People with wider pupils are more likely to end up with red eye in photos, whereas those with smaller pupils are less likely to.
HOW TO HAVE A SIGHT TEST
Before you see your optometrist, you will have to wait in the waiting room surrounded by outdated copies of every magazine imaginable. This is where you will discover the true meaning of the word "patient".
Once you have found the chair, the optometrist will slip a pair of heavy metal glasses on you that look like they have been knocked together by the local blacksmith. Whatever your optometrist tells you, these are not the latest in high fashion.
The eye test itself starts when you are asked what the lowest line on the eye chart is. Don't waste time by saying "Printed in the UK". Rather say "What eye chart?" The optometrist will then slide a number of lenses into your special metal glasses and keep asking you whether it is better with this one or that one. This is just to wind you up - they are all exactly the same!
Remember, the phrase optometrists hate most is "they are much of a muchness". Say this once too often and they will send you home with a pair of glasses that make you see round corners, and when you complain they will tell you that all glasses are "much of a muchness"!
Optometrists also like to ask whether the circles are clearer in the red box or the green box. This is no time to tell them you are colour blind! Just make a choice and go with it.
At some stage the optometrist will want to take a closer look at your eyes. While he is staring into your eyes, its important to maintain eye contact, even if you get the unpleasant impression that your entire skull is empty, and he is thinking "oh my, there is absolutely nothing in there!"
If your vision needs correction, the optometrist may discuss the benefits of contact lenses over spectacles. You will find this very hard to believe as he/she smiles wearing the latest designer frames.
Finally, you will walk out of there with new glasses and crystal-clear vision, and suddenly see that your job, home and family are nothing like you imagined!
ALL EYES ON SAFETY
Statistics show that job-related eye injuries are common, and many of them can be prevented. Whether one works in an industrial setting, an office or even at home, the necessity to protect the eyes is an issue which is often overlooked. Injuries can include strikes, scrapes, penetration, burns, or digital eye strain. The effects of eye injuries can range from mild discomfort to permanent damage, sometimes requiring time off work or even a change of occupation. The best way to prevent these problems is to be aware of the hazards and what can be done to avoid them.
Types of Eye Injuries
Most eye injuries occur when small particles strike or scrape the eye, for example dust, wood chips, or slivers of metal, scratching the cornea. They are usually discharged by machinery or blown by the wind. Larger objects may strike the eye resulting in trauma to the eye or eye socket.
Sharp objects, such as nails, staples, or shards of wood, glass, or metal may penetrate the eye, and can result in permanent loss of vision.
Industrial chemicals or certain cleaning products used in the home are common causes of chemical burns to the eyes and surrounding eye tissue, while welders are at risk for injury due to flying debris as well as ultraviolet radiation and photochemical burns.
Health care workers face eye hazards from infectious contaminants which can be spread through the mucous membranes of the eyes as a result of direct exposure to blood splashes and respiratory droplets, or from touching the eyes after handling them.
Spending long hours in front of a computer or on a tablet or smart phone can result in digital eye strain or computer vision syndrome, an increasingly common complaint affecting more and more people in this age of rapidly advancing technology. Symptoms include blurred vision, headaches, and dry eyes, as well as neck and shoulder pain.
Promoting Eye Safety and Eye Health in the Workplace
The first step towards promoting eye safety is understanding the risks, assessing the environment and identifying the potential hazards.
Protect the eyes with appropriate protective eyewear, such as safety goggles or glasses, face shields or helmets. When choosing protective eyewear consider the nature of the hazard, the extent and circumstances of exposure, and personal vision needs.
For most circumstances, impact resistant safety glasses will protect the eyes from flying objects that could pierce, bruise or scratch the eyes. However, they do not provide complete protection from all elements, in which case safety goggles would be a safer option. Safety goggles are designed to minimise exposure to contaminants by forming a seal against the face. They are sometimes worn over safety glasses and can be worn over prescription glasses. Consult your optometrist about prescription safety glasses or goggles which will protect against flying objects, radiation and chemical contaminants, while addressing your individual vision needs.
Ensure that protective eyewear fits comfortably and securely and allows for sufficient peripheral vision.
Replace protective eyewear regularly. If there are signs of damage this could compromise eye protection and can potentially cause injury.
Modify your office workspace to ensure comfort and prevent eye strain. Minimise glare and reflections on the computer screen and avoid having lights directly overhead or behind you. Dust and fingerprints can reduce clarity and increase strain, so keep the computer screen clean.
Ideally, the centre of your computer screen should be 10-15 degrees below eye level and 20-24 inches away to keep your eyes and neck comfortable. Maintain the brightness of the screen at a comfortable level. If you are alternating between the computer screen and paper work, try to keep them at the same working distance.
Staring at the screen for prolonged periods leads to eye strain so take frequent breaks by following the 20-20-20 rule - look away from the screen every 20 minutes at something 20 feet away for 20 seconds. Don't forget to blink regularly! It has been reported that we tend to blink less often while concentrating on work, compromising the lubrication of the eyes.
Talk to your optometrist about glasses that would make working on your computer more comfortable.
What to Do in the Case of Eye Injury
Any injury or trauma to the eyes should be taken seriously. The key signs to look for are a visible wound or bloodshot appearance, blood or fluid leaking from the wound, partial or total loss of vision, pain in the eye or eyelid. As a general rule do not touch or rub the eye.
The eye often cleans itself of foreign objects or particles by tearing. If this does not happen lift the upper lid over the lower lid and roll the eyes around. Flush generously with water, keeping the eye open. Don't rub the eye. Visit your doctor or optometrist to ensure that the object is no longer there and the eye is not scratched.
If an object has penetrated and is embedded in the eye do not try to remove it as this may cause further damage. Cover the eye lightly with a piece of gauze or eye shield. Do not apply pressure to the eye. Seek immediate medical attention.
If there has been a chemical or infectious splash into the eye, try to keep the eye open as closing it may trap the chemical in the eye. Flush the open eye with water for at least 15 minutes. Seek medical intervention immediately.
Blows to the eye can cause eye trauma. Gently place a cold compress over the eye at 10 minute intervals. Do not place directly on the tissue around the eye, rather wrap it in a cloth. Keep the head and eyes as still as possible. Be aware of any signs of bleeding, changes in vision or other visible injury. See a doctor to determine if there is serious damage. After 24 hours, warm compresses may help lessen bruising.
For cuts or puncture wounds on the eye or lid immediate medical intervention is essential. Do not wash the eye or eyelid. Protect it with an eye shield or the bottom half of a paper cup gently taped over the eye and keep the head and eyes as still as possible. Do not apply pressure.
No matter what your job is, your eye safety in the workplace should be a top priority. It won't only ensure your health, but it can also boost your productivity and efficiency.
June is Youth Month, so I'm sending my best to all the millennials out there (and the millennials at heart). It's also the month with the shortest day of the year, so when it's over we can start counting down to spring. But here's something I didn't know until my pal Wikipedia told me: June is named after Juno, the Roman goddess of marriage.
When I got to thinking about it, there are some mighty interesting things that married couples do with their glasses. So this column is especially for them. And like I always say, I'm just an old pair of glasses so what do I know? But here I go anyway...
We've all been in restaurants, and we've all seen this couple. Two people, one pair of glasses. You know who I'm talking about. He puts on the glasses and reads the menu. Then she puts on the glasses and reads the menu. Then he takes the glasses again because he's changed his mind. And just when they're ready to order, the waiter arrives with the specials board and it starts all over again.
On another note, it seems a spouse poses the biggest potential threat to a pair of glasses. How many people have had their glasses lost, broken or sat on by their significant other? Spouses have this knack of inadvertently causing harm to one another's glasses. It's true... the way I see it, getting married is the single biggest danger to glasses and sunglasses the world over.
Of course, glasses always feature in the classic married couple line. You know, the one called "Have You Seen My...?" The end of that sentence could be car keys/wallet/Filofax etc. But glasses are undoubtedly the most common object in that refrain. A person has trouble finding lost glasses because he/she can't see, because he/she isn't wearing said glasses. Then again, a spouse won't be much help because he/she can't see either. Why? Because as mentioned above, they share a single pair of glasses. So it's less a case of losing "my" glasses and more a case of losing "the" glasses. One pair gets lost and nobody can see.
Then there's the old joke about the couple who've been together for so long because of the way he looks and the way she sees. But no one tells that one like my grandfather did. So I won't even try.
Anyways, happy June month everybody. And here's to your beloved... for richer or poorer, in sickness and in health, for better or worse, and sharing glasses in restaurants.