Why Do I Need Glasses? Part I

Your roommate wakes up in the morning and has perfect vision but when you wake up... you can't see squat. Why?

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Part I

Glasses can be incredibly simple yet incredibly complex. Elegant yet cumbersome. Helpful, yet, in some cases, damaging. Part I is the beginning of a several-part series as there is simply too much to cover and too many cases to consider. I would be doing you, the reader, an injustice by attempting to lump so much into one article.

Thus, let us start by considering the case of simple nearsightedness and astigmatism in a person with the absence of any disease. And remember, there is a lot more to consider, especially neuro-anatomy and binocularity, that factor into vision that I will not cover in this article.

Vision, in its most basic form, relies on focusing light at photoreceptors in the back of your eye. Stay tuned for a full article that will explain basic eye anatomy, however, until then you might want to freshen up with some wikipedia.

When your eye doesn't accurately focus light on photoreceptors as it should, we call it refractive error. The length of your eyeball is the primary reason why you may have this error. Eyes that are too long tend to focus light before it reaches the photoreceptors (myopia/nearsighted) and eyes that are too short tend to focus light after it passes the photoreceptors (hyperopia/farsighted).

Imagine a pro NFL quarterback on the 1 yard line of a football field. It's getting far too close to the season for me not to drop a football analogy in here. Sorry, not sorry. Lets say this quarterback is practicing throwing at a very specific distance, 50 yards. Now imagine a wide receiver standing on the 51 yard line. The quarterback's pass will soar in the air to land perfectly, and precisely, into the wide receiver's likely gigantic hands. This is like a normal eye that doesn't need glasses; because the light (the football) focuses exactly on the photoreceptors (the WR).

Now, imagine this WR is actually a player from the ____ (insert terrible team yourself, because I haven't checked with an attorney to see if I can actually bash on teams I don't like) and he stands too far from the QB, completely misjudging the trajectory of the pass. The football never even reaches him, only to bounce pitifully on the 51 yard line in front of him. This is the nearsighted eye, or as we call, the myopic eye. The light (the football) focuses before it reaches the photoreceptors (the WR).

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http://www.freeimages.com/cedar-31004

"If you don't stand on that damn there 51 yard line, Jerry, like I've done told you to, there will be no team showers following practice!"

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Further diving into this terrible excuse for an analogy, how far the WR is from the 51 yard line determines how far he was off from catching the ball, and, in our case, how blurry your vision is. This is not like in football where an incomplete pass is an incomplete pass and regardless the WR needs to be benched. With eyes, the closer the light is to focusing on the photoreceptors, the better the image quality will be. The WR who is 5 yards too far fares far better than the WR who is 25 yards too far.

I'm going to go back to watching preseason football games, however, if you want to know how glasses fix this horrible conundrum, continue reading.

#Glasses #Health