Challenge Accepted

(please wear protective eye-wear)


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Eyesight Color Test

Click the image above to take a short test that will tell you how well your color vision is.

I scored a 16.

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Can Dogs See Colors?

by Stanley Coren, Ph.D., F.R.S.C. in Canine Corner at Psychology Today Dot Com



Probably one of the most frequently asked questions about dog's vision is whether dogs see colors. The simple answer-namely that dogs are colorblind-has been misinterpreted by people as meaning that dogs see no color, but only shades of gray. This is wrong. Dogs do see colors, but the colors that they see are neither as rich nor as many as those seen by humans.

The eyes of both people and dogs contain special light catching cells called cones that respond to color. Dogs have fewer cones than humans which suggests that their color vision won't be as rich or intense as ours. However, the trick to seeing color is not just having cones, but having several different types of cones, each tuned to different wavelengths of light. Human beings have three different kinds of cones and the combined activity of these gives humans their full range of color vision.

The most common types of human colorblindness come about because the person is missing one of the three kinds of cones. With only two cones, the individual can still see colors, but many fewer than someone with normal color vision. This is the situation with dogs who also have only two kinds of cones.

Jay Neitz at the University of California, Santa Barbara, tested the color vision of dogs. For many test trials, dogs were shown... Click here to continue on to the rest of the article..

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Sight and Vision

Available here..

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Eye Floaters

(I thought it was just me..)



Today I found out what causes “eye floaters”.

For those who’ve never experienced this phenomenon, eye floaters are little oddly shaped objects that appear in your vision, often when one looks at bright light such as a blue sky. Their shapes vary greatly, but will often appear as spots, cobwebs, or randomly shaped stringy objects. These are not optical illusions, but rather something your eyes are actually perceiving. There are a few different things that can cause this, but in most cases these eye floaters are caused by pieces of the gel-like vitreous breaking off from the back portion of your eye and then floating about in your eye ball.

The vitreous humor, or often just “vitreous”, is a clear gel that fills the gap between your retina and lens, helping maintain the round shape of your eye in the process. This gel is about 99% water and 1% other elements; the latter of which consists mostly of a network of hyaluronic acid and collagen. Hyaluronic acid ends up retaining water molecules. Over time though, this network breaks down which results in the hyaluronic acid releasing its trapped water molecules. When this happens, it forms a watery core in your vitreous body.

As you age then, pieces of the still gel-like collagen/hyaluronic acid network will break off and float around in this watery center. When light passes through this area, it creates a shadow on your retina. This shadow is actually what you are seeing when you see the eye floaters.

Continue reading..

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