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Archive for November, 2015

What actually happens to your eyes when you sleep?

Monday, November 30, 2015 @ 05:11 PM
Author: Amit Mathur

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Do you ever wonder why you see what you see when you dream? Though nothing is known for certain, there are speculations as to what happens to our eyes when we sleep and dream.

Certain things are known. For one thing, when you close your eyes, your eyes are still able to detect light. This is why we sleep better in the dark, why when the sun rises or when someone turns on the light we are woken up. Our eyelids protect our eyes from the external visual cues that might otherwise keep us awake. Also, our eyelids keep our eyes from drying out over the night by keeping the moisture to the cornea. This is a very important part of what happens.

When you’re awake, your eyes send information constantly and at such a rapid-fire rate to your brain, you don’t even notice it’s happening. However, when you are sleeping, your eyes stop sending your brain this “visual data” so the response and processing times slow down naturally. This is why when you do wake up, it takes your eyes a little bit of time to readjust to what you’re seeing and the light. It can take up to 30 seconds for your eyes and your brain to wake up.

You may have heard of the different stages of sleep. There are altogether five stages: 1, 2, 3, 4 (called non-REM) and the fifth stage, REM (rapid eye movement). Generally speaking, you go through each of the five sleep cycles repeatedly when you sleep, but not equal amounts of time are spent during each of the stages.

  • 30% is spent during stages 1, 3 and 4

  • 50% is spent during stage 2

  • 20% is spent during REM

So what happens during each stage of sleep?

Stage 1: your eyes roll slowly sometimes opening and closing a little bit.

Stages 2-4: your eyes are completely still and you fall into a deeper sleep.

REM: your eyes start to move around in all directions really fast. Despite your eyes not sending any information to your brain, the part of your brain that processes this visual information (called the visual cortex) is still found to be active during REM. Scientists believe that this is happening because your brain is, in essence, storing all the visual information you received during the day. And as it turns out, this is the time when you dream.

A study at Tel Aviv University found that our eyes function the same during REM sleep and when we are awake and sending image information to our brain for processing. This same research concluded that our eyes are in fact responsible for the images we see in our dreams and the neurons in our brain continue to react the same when we are dreaming. That is to say, the images you see while you are dreaming are images you’ve already processed when you were awake, only this time your brain is telling your eyes what it wants to see.

October 8 is World Sight Day — Will You Take The Challenge?

Monday, November 23, 2015 @ 05:11 PM
Author: Amit Mathur

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What a lot of Canadians don’t realize is that 80 percent of the world’s blindness is actually avoidable. Avoidable blindness is blindness that can either be prevented or treated with known, cost-effective treatments. It means you don’t have to go blind. You can take care of your vision and prevent long-term detrimental impacts.

What Is World Sight Day?

Thursday, October 8, 2015, will be World Sight Day. An annual day of awareness surrounding blindness and vision impairment around the world, and how it can be prevented and/or treated.

This day is meant to shed some light and bring more understanding around the fact that 80 percent of blindness can not only be prevented and treated if everyone had access to proper vision and eye care services.

What Are Some Of The Causes Of Blindness?

In some instances, blindness can be caused by simply not having a proper pair of eyeglasses to help fix a simple refractive error. Other potential causes include diabetes, cataracts, and glaucoma.

Seeing Is Believing

It’s true that vision impacts every aspect of our lives. From students learning in the classroom, to adults feeling empowered in the workplace, sight isn’t a privilege, it’s our natural right. And everyone should have access to universal eye care from trained professionals to help properly detect and treat any and all vision problems, as well as catch early signs of other serious health conditions.

A Worldwide Initiative

Although the governing body around World Sight Day is UK-based International Agency for the Prevention of Blindness (IAPB), this still affects us here in Canada. This is a problem that knows no geographical boundaries, and doesn’t care about skin colour or religion. Blindness can affect each and every one of us, and should be treated as such.

How You Can Spread The Word

The IAPB has created a photography competition to help spread awareness of World Sight Day. All you have to do is submit your photo under one of three categories (professional, amateur or junior), and your photo must showcase the impact of eye health in people’s lives under one of the sub-themes such as eye screenings, families, guide dogs, eye care professionals, etc. Then, simply share your photo through Facebook or Twitter and invite everyone in your network to vote for your photo. The photos with the most likes/shares will win one of several prizes. And don’t forget to tag #EyeCareForAll. [http://photocomp.iapb.org/]

To learn more about World Sight Day, visit their website http://www.iapb.org/wsd15 and help spread the word!

9 Really Cool Facts About Eyes You’ve Never Heard Of Before

Monday, November 16, 2015 @ 05:11 PM
Author: Amit Mathur

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Eyes are some of the most complex, intricate and fascinating parts of the body. In fact, there are more than two million parts to the eye, which means after the brain, it’s the most complex and intricate organ in the body. We’ve compiled a list of interesting and strange facts about eyes, that we thought we would share with you.

Size.

Unlike some parts of your body, your eyes don’t grow as you age. This means, your eyes are essentially the same size when you are born, as when you’re a full-grown adult. And it has been proven that a fetus in its mother’s womb will start to develop its eyes only two weeks after conception takes place.

You can only see part of it.

On average, only one-sixth of your eye is actually exposed to the outside, the rest (the five-sixth) of your eye is safely being protected inside your head. Because the eye is such an intricate organ, with highly complex physiology, over time, the body has evolved to protect as much of it as possible. And since most of the functions of your eye happen where you can’t actually “see” it, your skull protects it from being damaged.

Blinking.

How many times do you blink? A lot. They say people blink an average of 17 times per minute; 1,020 times per hour; 24,480 times per day; 171,360 times per week. All the way to 9 million times per year. This also makes the eye the fastest muscle in the whole body, hence the expression, “In the blink of an eye.”

Tears.

Tears are a way for the eyes to defend themselves from foreign bodies such as microscopic items, dust, dirt, debris, bacteria and other such things that could potentially harm your eyes. However, you also produce tears when you’re sad. When you sneeze or have allergies, when you hurt yourself, and so on. Scientists have been able to prove that different tears are chemically different.

What you see.

In order for your eye to process what it sees, it has to translate the information. The way it does this is by turning the image upside down and dividing it in half, similar to cameras. Within a fraction of a second, your eyes, specifically your retinas, will rotate the image and piece it back together in order to send a proper “picture” back to your brain to let you know what you are seeing. This happens so quickly we never even realize it’s happening.

Red.

Although yellow, blue and red are considered primary colours, your eyes, again specifically your retinas, don’t actually see red. With the millions of receptions in your retinas, they are able to process blue-green and yellow-green colour-combinations, which means by process of elimination your brain is able to deduct that any other colour-combination will fall into the “red” category.

Red eyes in photos.

Raise your hand if you’ve ever looked at a photo of yourself and you had red eyes in the pic. We all have. Now with things like PhotoShop we can remove “red eye” but what causes it is actually the light from the flash reflecting the blood vessels at the back of your eye in a layer of tissue called the choroid. The choroid is found behind the retina and contains so many blood vessels (which are red from the blood) and when the flash gets reflected back, that’s what you end up seeing in the photograph.

Unique.

Fingerprints were once thought to be the only unique and distinguishing feature in a human. However the more we learn about eyes, the more we know that in fact the eyes are even more than fingerprints. Fingerprints have 40 unique characteristics while the eye has more than 256 unique characteristics within the iris (the coloured part of the eye). This is also why biometric eye scans are more secure than fingerprint scans.

Processing information.

Because of the rapid rate at which our eyes are processing information, we are constantly taking in and analyzing. Some scientists suggest that your eye can focus on 50 different objects per second. That can be as much as 3,000 objects per minute or 180,000 objects per hour. So just think of what you’ve actually seen (and noticed) that you didn’t even realize!

What are photochromic lenses and are they for you?

Monday, November 9, 2015 @ 10:11 PM
Author: Amit Mathur

 

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Most people with prescription eye glasses not only have one pair for indoors, but also require prescription sunglasses, so they can see when they are outside in the heavy sunlight. If you have two pairs of glasses, then you know the strain this puts on you in terms of having to carry around two pairs of glasses, as well as having to pay for two pairs of prescription glasses. And most of the insurance companies won’t cover all those costs, so it falls on you to pay for the difference.

There is a solution. A simple one at that. Getting photochromic lenses.

What are photochromic lenses?

Photochromic lenses are prescription lenses that automatically darken when they are suddenly exposed to sunlight or get back to being clear when you are indoors or when it gets darker.

Originally developed in the 1960s by the Corning company that used to manufacture Pyrex and Corningware, photochromic lenses are now more commonly known as transition lenses after the company (Transition Optical) that is the most well known in the market. But there are many different companies and brands that manufacture such lenses, and your optometrist can advise you on the best choice for the eyewear you select.

From a scientific standpoint, what sets these types of lenses apart is what they have that you actually can’t see. Extremely small molecules are part of the make-up of these lenses and when a large enough amount of UV rays hits the lens, these molecules react to the light. By structurally changing, the molecules are then better able to absorb a large amount of visible light and that is what causes them to darken. Conversely, once the light or UV rays are removed (or you go inside in a darker setting), the process is reversed and the molecules go back to their original shape and the lenses become transparent again.

Who needs photochromic lenses?

Your optician will give you the option of whether or not you would like these types of lenses. The choice is yours. But you should understand what their benefits are so you can make an informed decision as to whether you should get them or not. Here are a few points to consider.

  1. Cost: Yes there is an added cost to have a special coating put on your lenses. However consider the cost of having two pairs of prescription eyewear (sunglasses and regular glasses). Your insurance company might not cover the total cost for both pairs, so you might be out of pocket.
  2. Protection: Sure you might have a pair of sunglasses in your bag or purse that you can switch over to. But how often do you do that if you’re just going for a short walk to the corner store? The truth is, it takes very little time for UV rays to start affecting your eyes. By having your glasses automatically change to the appropriate level of protection, your eyes are literally always covered. It’s as simple as that.
  3. Convenience: Not to mention, if you don’t have to always carry two pairs of glasses with you, that quite literally takes a weight off. Imagine the extra space in your purse or bag. Not having to shuffle through to change from one pair to the other.
  4. Adaptability: These lens coatings are available for a variety of lens materials and adapt to work with different types of lenses including bifocal and progressive. So regardless of what you need, your covered.

THE EYES — Part 3 of 3

Monday, November 2, 2015 @ 10:11 PM
Author: Amit Mathur

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In the last part of our series in describing the eyes and how they function behind the scenes, we will examine how light is processed and the function of tears. Let’s begin!

Rods and Cones

We’ve already discussed the retina and how it has special cells called rods and cones which work to process light. Each one of your eyes has an astounding 120 million rods and an incredible 7 million cones. This is to help you see in great detail different shades of colour, as well as forms and shapes of items.

Rods detect the form and shape of items and specifically translate black, white and grey colours. Although rods can’t distinguish colour, they are what help you see things even when it’s very dark because they are so sensitive.

Cons, on the other hand, can distinguish colours, but require light for that. And within the cone family, there are three different types of cones. Each type of cone is specifically designed to distinguish a particular family of colours, red, green ad blue (the primary colours). These colours, as we learned early on, are the foundation of all other colours. The combination of these three different types of cones are what allow your eyes to see and detect the millions of different colours in the world.

Tears

Tears are an important part of the eyes and vision process. Tears are made from the lacrimal glands. The same way blinking helps keep dust and other little particles out of your eyes, tears do the same. When you blink, a small amount of tear fluid is secreted which also helps remove these small particles and ensures they don’t go into your eyes.

The other job tears have are to prevent your eyes from drying out. Once your lacrimal gland releases a bit of that fluid, it is then drained into your tear ducts. If you hurt your eye, have something in your eyes, your eyes will produce extra tears to protect the eye itself.

And of course, we all know that when we are sad, or laugh way too hard, we produce tears. Though crying doesn’t protect your eyes, tears are formed as a result of your brain sending a message to your glands.

Take Care Of Your Eyes

In the last few weeks, we’ve examined all the wonderfully complex parts of the eyes that work together, undetected, to allow you to see objects, colours, from a far and from close up. All in the blink of an eye, these things happen. But just as quickly, one can lose their vision. So it’s incredibly important to protect your eyes and treat them as you would any other part of your body. They are, in fact, more sensitive then other parts.

The things you should do to ensure you maintain healthy eyes, include maintaining a healthy lifestyle (including eating right and not smoking), protecting your eyes from UV rays, and wearing protective lenses when necessary, and having regular check ups with your eye care professionals to ensure everything is ok and there are no signs of disease or problems.