I require assistance from a bigger brain than mine. This is driving me nuts and my physics teacher doesn't speak english, my bio. teacher has trouble remebering my name and has in fact been calling me 'Charlene' 'Cordelia' and 'Sharron' (despite my objections every time he takes attendence) for the past 2 years. I'd like this explained in terms of scientific principles please.

I'm short sighted, why when I look in the mirror without my glasses do close things seem in focus and far things seem just as blurry if not more so. My brain just can't figure it out and is leading me to believe my IQ score was a cruel cruel joke.

Thanx, you will be saving me from many more sleepless nights.:(

By close things to you mean things that are close to the mirror? I.e. you look into the mirror then at the object?

Your mirror may have a slight curvature, but I wouldn't bet that this is the cause.How bad is your short-sightedness? 1m, 2m, 10m?

In my oh so simple brain even with out my glasses when i look in the mirror every thing should be in focus. I know it's not by I can't figure out why and it's making me crazy.

I would guess that what you are thinking is that when you look at
a photo at 12" everything is in focus, why is it that when you look into
a mirror from 12", it is not? The image you are looking at in the
mirror is reflection of objects both near and far, they are still at
various distances from you, not the 12" to the surface of the mirror.

But why do i see them blurry??!! I think I'm just going to have to put this on my incomprehensible (by my brain) list. So far I have THIS.

say you have an object 10 m behind you and you are 1m in front of a mirror. The light from the object will be seen by you looking in the mirror as if it has travelled 12m, not 1m.

But how does that relay to my squished optic nerve?

Perhaps it's your belief that a "squished optic nerve" is responsable
for your short sightness. You eyeball itself is the problem. It is unable
to focus correctly on distant objects, whether you are looking directly
at the object or a reflection of the object. The optic nerve just relays
the image created on the back of your eyeball to your brain. If the
image is out of focus, that's the way your brain "sees" it. Your
glasses provide a way for your optic nerve to receive properly
focused images of distant objects, reflected or not.

I think I'm starting to get it. Thanx all.

I don't know if this is what you are looking for, but do you know know why your eye isn't able to focus on distant objects?

I hope I'm not [preaching] telling you what you already know, but this is how it works. When I was younger, I thought that the eye worked like a pinhole window, which would explain why the image formed on the back of your eye would be upside down, like people say. How it actually works is the curvature of your cornea, the lens-thingy on the outside, bends the light so that light coming from a point source and entering your eye at any location on your pupil will all get bend such that it focuses towards a point on your retina, the back of your eye. Otherwise not enough light would be entering into your eye, and you wouldn't be able to see.

The problem is getting the curvature right. If your cornea is curved wrong, the light will be bent more than is optimum, and light that is coming from a source farther (futher??) away will focus to a point before it impacts your retina; then it turns into a sort of cone-thingy and spreads out the light over an area. Which is why you see blurry.

Either that, or you have a dirty mirror :) Or you need to stop using so much hot water in the shower! :D

That really makes sense to me now. Thanx sankuro. I can now sleep soundly.