Eye disability

[Degenerate]

This should be the right plave to post about this. What causes shortsightedness or longsightedness? What are ways to prevent it if any? What treatments are given or ccan be given? Surely there must be a cure?

I often hear about starting at something short distant too long (reading a book) can cause eye damage. But are there more scientific reasons? And also, shy do some people get shortsightedness "more" than others?

 

[AndyHui]

In my case, it's genetic, but there are a number of factors that contribute to it.

In the case of short-sightedness (myopia), it's often a case of "use it or lose it". The eye focuses on a short distance for an extended period of time, cause the muscles that control the lens shape to weaken. The lens is then unable to be pulled into the correct shape for long distance focussing.

Take the case of staring at a monitor for an extended period. Precisely the situation described above. I've heard that refocussing your eyes on a distant object (away from the screen) can make a material difference to the speed at which myopia increases.

I've heard of several other reasons for short-sightedness, such change in the size of the eyeball without a corresponding change to the lens, but then, this is mostly what I have heard.

Any eye doctors here? We probably have one or two lurking in OT who would know.

 

[navyrn]

The iris has mucles that warp the lense. This is what allows you to focus. Some people are born with lenses that are "pre-warped" and everyone warps over time. That is why we tend to need glasses to read when we get older. When people are far or near sighted, the focal point of the lens is off (the focal point is actually before or behind the retina) and the muscles can only bend so much to compensate. What glasses do is bend the light so the focal point is corrected and the muscles don't have to work so much. People with weak prescriptions can go without but they get headaches and "tired-eyes". This is the mucles working too hard to correct and they strain. Astigmatism is different. This is where the focal point of the lense is not quit centered on the retina. In other words: Astigmatism is where the movie camera is only showing halfway on the screen. Near and far sightedness is when the movie projector is initially in focus and you move it closer or further from the screen without refocusing it.

There is a surgery to correct most of this. Of course it depends on the nature and degree of the problem. It is a laser surgery that burns the eye and when it heals things are brought into correct allignment (i know i way understated the actual procedure.)

Bottom line, get your eyes checked and ask the doc for your options. Good luck.

 

[Mingon]

<< In the case of short-sightedness (myopia), it's often a case of "use it or lose it". The eye focuses on a short distance for an extended period of time, cause the muscles that control the lens shape to weaken. The lens is then unable to be pulled into the correct shape for long distance focussing. >>



I thought short sightedness was due to the muscles being too strong, and your describing being long sighted.

 

[Degenerate]

Is the relaxed state of the musles for the eye allowing you to see far distant? in other words, is your eye more relaxed when looking at far objects than short? If that is right then i should not have aproblem looking at long distance since its the 'normal state'. Unless as some of you mentioned that the eye is not 'adjusted' properly.

 

[Ju1cyJ]

Iirc, some problems develop with the shape of the eye, after awhile it begins to flatten out (a la gravity). Therefore the front of the eye is more concave, and thus the focal point is not in the same place it was, causing out of focus vision. I believe that laser surgery cuts the eye and reshapes the lense by making little staggering steps of the lense.

(I can't remebr exactly what that kind of lense is called, it is like when they make a really big lens, but because it would be really hard to do this they use a lot of smaller pieces and it kinda looks like stairs meeting at the top. I think it also has to do with the fact that after the light goes in parrallel, then bends out and goes to the focal point, if the big lense is too thick things will be messed up since it will take quite a bit more time for the rays to get through different parts of the lense.)

It's pretty cool how they do laser surgery, they use a bunch of weak lasers that dont harm u, butonce they meet at the same location it has the power to burn/cut/whatever. I think the process is the same with some brain tumors too.

 

[Degenerate]

<< the lense by making little staggering steps of the lense. >>

wound't this make your vision worse because the light gets diffracted?

 

[bacillus]

laser surgery works by altering the shape of the cornea, no physical changes are made to the lens itself!

 

[Mingon]

All I know (being short sighted) is that my eyes actually get better when I dont use my glasses for a while. Also sunlight helps me to focus better. Mostly its due to vdu work, but genetics does play a part.