Archive for the ‘Eye Care’ Category

Depth Perception, What Exactly is It?

Have you seen the movie Gravity? Did you see it in 3-D?

If so, you probably found yourself marveling at the amazing technological effect of seeing Sandra Bullock and George Clooney tumble through a very realistic depiction of the depths of outer space.

But you probably never find yourself marveling at the even more amazing technological effect of seeing everything in the world in 3-D – achieved by simply having two eyes, as well as a brain that blends the images your eyes see.

Very simply, this is depth perception, meaning the ability to see things in three dimensions – length, width, and depth – and to perceive how near or far away people and objects are.

One way humans perceive depth is by having eyes that are spaced a little bit apart. This is contrary to certain animals that tend to be prey, and have evolved so that their eyes are on either side of their head to enable them to spot predators. (Predator animals, on the other hand, or paw, usually have eyes positioned closely together, like humans, to enable them to spot, chase, and swoop down upon prey.)

Like those clunky 3-D glasses you wore while watching Gravity, human eyes spaced a little bit apart see two slightly different images, based on each eye’s position on your face. These two slightly different images are called binocular visual cues. They’re called binocular because the images are seen by two eyes.

Here’s a fun way to test your binocular vision. Take a look at the picture of the baseball below:

Now hold up one finger about six inches away from your face, in front of the picture of the baseball. If you focus your eyes on the baseball, you will see two somewhat transparent images of your finger, on either side of the baseball.

Now focus your eyes on your finger. You will see two somewhat transparent images of the baseball, on either side of your finger. That’s depth perception.

Here’s another way to test your depth perception, and to see whether one of your eyes is dominant.

Hold your finger in front of the baseball, just like before. Focus on the baseball and close your left eye. Your finger should appear to the left of the baseball. Now open your left eye and close your right eye. Your finger will seem to jump to the right of the baseball.

Once again, as in the previous test, if this is what you see, you have binocular – also known as stereo – vision. However, you may have faulty depth perception if you experience any of these things:

  • You can see your finger better on one side than the other.
    The view of your finger is larger with one eye than with the other.
  • One eye’s finger image appears right over the baseball, while the other one is far to the left or right.
  • You can only see one finger image.

If you do experience any of these things, it would be a good idea to get your eyes checked by an ophthalmologist or an optometrist.
 

 
But what if you have sight in only one eye? Do you still have depth perception, even if you don’t have binocular (stereo) vision?

Yes! Here is a way to test your one good eye for depth perception.

Let’s say you are doing this indoors. You will need stationary objects in three different distances from you: one object close to you, one a little farther away, and one still farther away from that one.

Let’s try this with three objects you may find indoors: a chair (close to you), a filing cabinet (a little farther away), and a table (farther away).

You can do this outside, too. Try it with, say, a bush (close to you), a tree (a little farther away), and a house (farther away).

Of course you don’t have to use these three indoor and outdoor objects, in these three positions. You can use them in different positions, or you can use three other objects, as long as the one farthest away is large enough so you can see it well.

Focus on the object in the mid-distance range – the table if you are inside, the tree if you are outside, if you are using those objects. Then walk from side to side.

As you focus on the midrange object, perhaps the filing cabinet or tree, you will see the object closer to you (the chair or the bush) move to the opposite direction from where you are walking. You will also see the object farther away (the table or the house) appear to move in the same direction that you are moving.

If you can see this with one eye (if you are sighted in both eyes you can close one eye while you do this), you have depth perception!

Another way either one or both eyes can perceive depth is by perspective – which means how objects appear based on the position of your eyes in relation to the object.

Here’s a very common way we perceive perspective. When we’re standing on the ground and looking straight down at parallel lines, they appear parallel:

If you click the below link it will take you another tab. Click the red “add perspective” ball, and you’ll see the lines converge (and be sure to come back when you are done). It’s like when you look at railroad tracks off in the distance as they approach the horizon. They appear to meet at what is called the “vanishing point”:

http://psych.hanover.edu/krantz/art/linear.html

Just like the way perspective can trick the eye into seeing parallel lines that appear impossibly to meet, artists can use perspective tricks to create other optical illusions. Look at this one, created by the German psychiatrist Franz Muller-Lyer in 1889:

The two parallel lines are the exact same length. You can prove it with your ruler. But the line on the top appears longer, because our brains perceive the inverted angles as lengthening the line.

What causes this? Theorists have advanced various explanations, none proven. If you are interested in exploring this further, you can read the explanations at the link below, and test their validity yourself:

http://www.rit.edu/cla/gssp400/muller/muller.html

Your perspective affects not just your view of distance, but the appearance of colors and hues you perceive as well. Check out this picture:
 

 
The gray bar across the middle of the picture appears lighter on the left and darker on the right. But that’s only because of the contrast between the gray bar and the different shades of gray in the background. The background is darker on the left and lighter on the right. Despite its appearance, the gray bar is actually the same color on the right and left.

In addition to appearing to vary shades of a color, sometimes our visual perspective can cause us to see colors that are not actually there. This is because our brains can perceive color in relation to other colors that are present. Take a look at this optical illusion, follow the simple instructions, and notice if you see green grass:

http://www.illusions.org/dp/color.htm

These optical illusions are all results of perspective – what you perceive as true is determined by your perspective, a principle that can apply not only in vision but in many other aspects of life, as well!

As you ponder this, here are some other fun optical illusions to look at and share with your family and friends, to get their perspective, too!

Tuesday, December, 10 2013 by

Eyelash enhancer can turn eyes brown

brown eyes
 
I’ve written before about the importance of eye makeup sanitation, noting that germ-infested cosmetics can cause a whole host of eye infections. Now I find out that, in the quest for longer lashes, some people may be willing to risk turning their blue eyes brown.
 
Until recently, individuals with sparse eyelashes were in a bit of a pickle. While mascara and even false eyelashes could help create the appearance of fuller lashes, cosmetic approaches had limited effectiveness. For many people, eye framing “doll lashes” was simply another unattainable beauty standard.
 
Then something interesting happened. Users of a glaucoma drug called Bimatoprost, sold under the trade name “Lumigan,” began to notice that their eyelashes appeared thicker and darker after they’d been using the drug for awhile. Researchers became interested in these claims and began running tests. Sure enough, the drug proved effective at not only treating glaucoma, but also encouraging eyelash growth. In 2008, the FDA approved the drug for cosmetic use under the brand name of “Latisse.”
 
To many people, the drug sounded like a miracle: Lush, full eyelashes are in demand. High-end mascaras cost $25+ and many women pay even more for eyelash tinting and extensions. Being able to grow thicker lashes sounded like a dream come true.
 
Unfortunately, like most drugs, Latisse use has potential side effects. Some users reported blurred vision and redness. Others noted a darkening of the eyelid and under the eye. In some cases the eyelashes grew too long, resulting in discomfort and scratched corneas. Sloppy application could result in the medication getting onto other parts of the face, leading to unwanted hair growth.
 
And then there’s the bit about eye color: Some blue eyed users found that their eyes had turned permanently brown.
 
The drug contains prostaglandins, which help to relieve the dangerous pressure that threatens the eyesight of glaucoma patients. These prostaglandins can trigger increased melanin production in the eyes, permanently altering their color. While users are cautioned to keep the drug on the lid, mishaps can occur, with the drug spreading into the eye itself.
 
How do you feel about drugs like Latisse? Is beauty worth the risk?

 

 

Tuesday, October, 1 2013 by

In the Eye of the Beholder: 5 Eye Makeup Safety Tips

Women have been using eye cosmetics for generations and for good reason: A pretty pair of eyes has been known to sweep many a suitor off his (or her) feet. The flip-side of this is that  makeup is notorious for causing irritation and infection and there are few things more unattractive than peepers that are red, swollen and oozing green muck.

 

 
If you are going to prettify your peepers, put a little thought into the makeup you use and how you use it:

 

1. Pore Over Packaging

Your eyes are sensitive organs: Easy to irritate and easy to damage. Contaminants in eye makeup, such as bacteria or foreign substances cause a world of pain. Use your common sense when shopping and make sure a product’s packaging is intact and sealed.

(If there is a “sell-by” date on the package read it, abide by it.)

Tip: Be extra cautious while shopping in the “bargain bins” at drug stores and boutiques, as some of the makeup in there can be pretty old, even if well-sealed and in its original packaging. Also, check out the FDA’s Import Alert of contaminated cosmetics.

 

2. Be Selfish

Never, never share makeup with a friend. No matter how much she begs. No matter how long she pleads.

(Don’t share even if there the cutest guy in the world is at the bar and she really needs an extra coat of mascara.)

Sharing makeup is just asking for trouble. It’s how infections get spread. Don’t do it.

Tip: If you are the “need to be needed” sort, keep a package of unused, trial-size cosmetics in your purse so that you can dole them out to grateful friends and strangers in the ladies’ room. Just keep your own stuff for yourself.

 

3. Don’t Be a Hoarder

If you love a mascara, set it free after four months.

 

 
(You can always buy another.)

Eye makeup doesn’t improve with age, so don’t stockpile or hang onto a product for months or years. Mascara and eyeliner should be dumped 4-6 months after opening. Toss other cosmetics after a year.

Tip: If you hate the idea of tossing a beloved shade because it’s no longer being manufactured, don’t fret. There are companies that will custom blend shades for you. Just send ‘em a sample of what you already have and they’ll match it.

 

4. Get a Clean Slate

Got an eye infection? Lucky you. Now you get to go shopping for all new eye makeup!

(Yep, that’s ALL new. No time for getting sentimental.)

Never, ever keep eye makeup around after an eye infection. It all needs to head for the trash. If you use it again, you risk reinfecting yourself.

Tip: Shop wisely if you are on a modest budget. Department store brands often feature “gift with purchase” offers that may include generous samples of shadow, liner, mascara, and eye makeup remover. For the price of one or two items, you’ll end up with a nice “starter wardrobe” of eye makeup.

 

5. Block Those Rays

Don’t forget the importance of protection against UV rays when choosing your eye makeup. Some makeup (such as mineral eye shadow) provides this protection, but some products don’t, so it is up to you to protect your eyes, and the skin around them, from the sun.

How to do it? Look for eye care products (such as moisturizers) that include a sunblock. You should also make sure that your glasses and sunglasses have a UV coating.

 
Tip: Try layering UV products around your eyes for serious protection: Start with a moisturizer that contains sunscreen, then add mineral eyeshadow. Complete your look with a pair of UV-coated sunglasses or regular specs.

Wednesday, May, 16 2012 by