10 Facts & Myths about Your Eyesight
Eating carrots will help you see in the dark
Myth: Eating carrots wil not help you see in the dark. This myth continues to live, because of the fact that carrots are rich in beta-carotene (Vitamin A). Vitamin A is used by your body to convert light into a signal that is sent to your brain. This signal allows you to see in low light conditions.
So, if Vitamin A helps you see in the dark, why don’t carrots, rich in vitamin A help you see in the dark? Like most people, you very likely already have all the vitamin A from your regular diet that your body needs. Ingesting more vitamin A will simply result in it being metabolized and not used by your body.
THE COOLEST PART OF THIS MYTH
This myth was actually concocted purposefully as a strategy to defeat NAZI soldiers!
According to a book by Robert Buderi called “The Invention that Changed the World”, during WWII Nazi planes were very effectively being intercepted during night-time missions. The Brittish created a rumour that their secret to success was feeding their pilots massive amounts of carrots. What was the real secret? The invention of a RADAR set for aircraft use by Scottish physicist Robert Watson-Watt. Pretty sneaky, hey?
Vision can be corrected with eye exercises
Part truth – Part myth: This claim is a tricky one to sort out. There is some partial truth here.
The myth: If you have common vision insufficiencies such as being farsighted, nearsighted, have an astigmatism or presbyopia (blurry vision for close objects), don’t throw away your prescription lenses and start your eye calisthenics just yet! Despite claims you may find, there is no scientifically founded evidence that any eye exercises will correct these conditions.
The part that is true: …well, sort of true. There are some hypotheses that some eye exercises and vision practices could potentially delay the need for vision correction as you age. But it is best to think skeptically, when taking in information promoting these ideas as facts. Although the information may seem true from an intuitive perspective, there are not yet any properly conducted study’s that have produced empirical evidence to support these ideas.
Once last important item: At Eye Expressions, Dr. Dave does prescribe something called vision therapy. As part of the vision therapy regiment, there are guided exercises conducted in the clinic, and sometime in addition, prescribed ‘homework’. This practice can help correct some vision conditions, that would otherwise be treated with lenses, or surgery. Vision therapy, however is not to be confused with the at home self-help ‘eye excercise’ remedies. If you feel you or a loved one may benefit from vision therapy, or if you have any questions about it, please book an appointment to see Dr. Dave at Eye Expressions Optical in Lloydminster.
20/20 is perfect vision
Myth: Some people actually have vision even sharper than 20/20.
So, what is 20/20 vision?
20/20 vision is simply the most widely accepted standard for ‘normal’ vision acuity. The numbers represent how well you can see in comparison to what is considered “normal”. For example, if your visual acuity is 20/50, that means that text you can read from 20 feet away can be read from 50 feet away by someone who has 20/20 vision.
Reading in the dark can damage your eyes?
Myth: Reading in the dark doesn’t cause permanent eye damage. However, it may cause temporary discomfort, as you may need to focus on the words longer in order for your brain to receive enough signal from your eyes to register the text you are reading. This will cause you to blink less often, which in turn means your eyes will not receive as much moisture on the surface. This cause of dryness is referred to as eyestrain.
Newborn babies don’t have tears when they cry
Fact: This is true. Tear ducts are normally not fully formed until a new born is at least 2 weeks old. The tear glands however are still producing fluid to keep the child’s eyes lubricated.
You actually see things upside-down
True! Well, sort of true. When light reflected off an object passes through the lenses of your eyes, it is projected onto the retina, located on the inside back wall of each eye. This image on your retina is in fact inverted. Your brain naturally makes you ’see’ the object as right-side up. Pretty cool, isn’t it!
Want to hack your brain-sight? …I mean, eyesight? First, take note that not only does your brain flip the perception of the image on your retina top to bottom. It also flips it horizontally (left and right).
Here’s what how you can hack your brain:
1. Find an app that will flip a photo on your phone horizontally (left-to-right).
2. Take a photo of your beautiful face with your phone.
3. Use the app to create a flipped version (Flipped left to right).
Now look at the original photo versus the one that is flipped. Which image of yourself do you like more? Most people will choose the ‘flipped’ version. “Flipped”, meaning the one that is most similar to what you see when you look in the mirror. Why? Well, you see your own face most often when you’re looking at a mirror, so this is what your brain has associated as what you ’should’ look like.
The feeling of ‘I look better in the mirror image of myself’ is actually part of the reason that some mobile app developers choose to render the mirror image of yourself when snapping a ’selfie’, rather than the unflipped image rendered by a regularly snapped photo. They want you to feel good when you use their product, so they give your brain what it wants. The mirror image of your smiley face.
People blind in one eye have no depth perception
Mostly false: You can think of a person with vision only in one eye as having ‘impaired’ visual perception of distance. So, how does this work?
Your brain is just as responsible for your sense of sight, as your eyes are. Think of your eyes as the lenses attached to a 3D camera, and your brain as the camera itself that renders the image. For depth of field, a primary method that your brain uses to gauge near to far, is by binocular disparity. Binocular disparity is works by comparing small differences in the image received by each eye. However, your brain also uses other cues to judge distance, such as sizes of objects, and changes in perceived geometry. For example, if you look down a straight road, it looks wide right in front of you, and narrows off into the distance.
Let’s hack your brain again! This one is very simple. Cover one eye and look around. Bet you can still make judgements of approximate distances to objects as you look around the room.
Too much screen-time can damage your eyes
Some Myth – Some Truth: This is actually a complex topic, and an important one since for most of us a typical day includes more and more screen-time as our world becomes more reliant on digital technologies. We may dedicate a future article to this topic. For now, here are a few quick notes on screen-time affects on eye health:
- There has been some research on this and there is something called ‘Computer Vision Syndrom’ AKA ‘CVS’.
- Temporary symptoms of CVS are eyestrain, blurred vision, headaches, neck & back pain.
- Over long term, there is evidence that there could be permanent damage to your vision.
- Among the discomfort and potential for harm to your vision, too much screen time can disrupt your circadian rhythm. (AKA sleep cycle)
- Screens tend to emit high amounts of blue light. Humans are subconsciously triggered to feel more awake, in the presence of blue light energy. So habits of viewing screens in the evening can cause a person to stay awake later than usual, or make it more difficult to fall asleep post screen-time.
What can you do to avoid potential harm from too much screen time?
- Use common sense – Take breaks from your screens and enjoy the real world around you.
- Listen to your body – If your eyes feel dry, it may be time to take a screen break
- Listing to your partner or parent, or whoever may mention that you’re spending a lot of time scrolling your favourite social site, or working too hard on that report for work.
Bright light can make you sneeze
Fact: This is true! Well, it’s true for some people. According to some sources, 18 to 35 percent of people find that emerging from dim to bright light, or even turning to face the sun will induce a sneeze, or two or three. It isn’t clear on exactly why this phenomenon occurs, but it does seem to be genetically inherited trait.
Are you a bright light sneezer?
A blind spot in your vision is normal
True! This is completely normal. However, if you notice any abnormality in your vision, you should consult a medical professional to determine the cause. The blind spot that is natural and normal, isn’t easily noticeable since your brain fills it in for you. Confusing? Let’s take a closer look at this.
First, why do us humans have a blind spot in our vision? Well, the way we see is by light being absorbed by photo sensitive cells called rod and cone cells. These rods and cones line our retinas, and have the job of converting light into signals that our brain uses to produce what you experience is the sense of sight. The rods and cones are distrubuted accross the retina, but there is a small area near the back centre of each eye where nerves and blood vessels pass through. With no rods or cones in that area, we have a blind spot in our vision.
So why don’t we notice this blind spot?
There are a couple hypotheses on this. In a nutshell, it appears either the brain actively fills in the blind spot for you, or it simply ignores it. Scientist have found evidence for both methods.
Can you ‘see’ your blind spot?
Or more accurately ‘not see’ it? Yes, you can hack your brain and find the blind spot in your field of vision. Technically there are 2 spots, since they are off-centre in each eye.
HACK YOUR BRAIN TO SEE YOUR BLIND SPOT!
1. Click the orange & blue rectangle above. If you’re on a small mobile device, it may help to turn your screen 90 deg. to landscape(wide), so the image is larger.
2. Now, starting with your screen about an arm-length from your face, cover or close your right eye and focus on the dot with your uncovered eye.
3. Slowly move physically closer to the image until you notice the triangle disappear from your peripheral vision. -You can make fine adjustments by turning your head slightly, once you notice the right area.
You just found the blind spot in your left eye! Did you also notice that not only did you not see the triangle, your brain also filled in the area with the same orange colour surrounding the triangle. Try it again covering your left eye and looking at the triangle. The dot will disappear and your brain will fill in your perceived vision with blue.
Deciphering Fact from Myth for Your Vision Health
With all of the electronic information in our daily lives, are all inundated with information every day. Sometimes it can be difficult to decipher what is true and what is a myth. It gets even more difficult to undertand fact from fiction when there is some truth in the claim, or the real answer is not difinitivley known.
At Eye Expressions, we really care about your health and well-bieng and enjoy promoting reliable information. If you have any questions about any of the content in this article, please book and appointment with Dr. Jade or Dr. Dave by clicking the button below.
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Our clinic is owned and operated by Dr. Jade & Dr. Dave of Lloydminster. Right next door, our eyewear gallery is managed by Melinda from Lloydminster. We love being part of our community, and we truly appreciate your support.