Registered: Aug 2012
08-30-12 10:51 AM
Response to Sam
“..We'd all love to be good profitable traders but would it be worth it to go blind in the process?..”
Being a trader is not going to make you go blind. Needing to wear glasses is not blindness. People who are blind would give anything to have their vision restored with a pair of glasses.
"..what I understand, the major cause of myopia/nearsightedness is spending too much time with your eyes focused close in. Our eyes were designed to focus at a distance. Do some research and you'll see that Myopia was a rare condition until people started going to school and they had to spend hours with their eyes focused close up on books..."
Your understanding is erroneous. Being short sighted makes your distance vision blurry to varying degrees, but every short sighted person has a close up point where their vision is very good. The more myopic you are the closer it is. Speaking as very short sighted person, as a child my distance vision gradually deteriorated and I was not taken to an optician. My close up vision was excellent. This naturally made me more interested in books or close up things that I could see clearly, and made things like socialising or team sports more difficult. I managed to achieve a -6.00D prescription by the age of 10, without the intervention of nasty optical people. Then despite having glasses I refused to wear them, bearing in mind this was 1970. I’d sneak them out of my school bag to quickly peer through if I absolutely had to see something far away. I don’t think that this is an unusual sequence of events. By my 20s I was -10.00
"...Optometrists will claim that myopia is an inherited condition but all the evidence shows that it's a behavioural condition. If peoplewere born with myopia, evolution would naturally eliminate the condition since those people would make poor hunters..."
No, people are not born with myopia it develops through childhood. Babies are born longsighted. Longsighted eyes typically have a less than average axial length eg newborn eyes. As the globe grows it achieves “normal” vision because it has grown to a “normal” length. Short sighted eyes keep growing and have a more than average axial length. Adults with myopia may have been poor hunters, but would be amazing tool makers or stitchers or butchers or berry pickers. That is such a simplistic thing to say. After 40, everybody has blurry close up vision, except myopes who can retain their near vision beyond this.
"...Optometrists have been taught that the cure for myopia is to prescribe stronger and stronger eyeglasses as your eyes become weaker and weaker.."
I was never taught this
..". It isn't actually a cure but it just compounds the problem. Its just like someone who can't sleep, the doctor prescribes them a sleeping pill. Then one pill isn't enough and the doctor has to prescribe stronger and stronger pills. Why didn't the doctor just tell the patient to exercise more and they'll sleep better..."
It isn’t anything like the sleeping pill analogy. To understand the relationship between near vision and myopia, you have to understand something about normal eyes that don’t need glasses.
That eye has approximately +60.00D focusing power when we look into the distance. When we look at something close we increase the power of the eye using a muscle that changes the shape of our crystalline lens, this is called accommodation. So for example if you look at something approx. 40cm away the eye increases its focusing power to approx. +62.50. Babies and small children have a massive capacity to accommodate. As we age we gradually lose this elasticity until in our 40,s we need to hold things further back to see them and by our 60’s we have none left.
Longsighted eyes are less than +60.00D so for an eye of +58.00D, +2.00D glasses are prescribed to correct it. Because of our ability to accommodate if that +58.00 eye is a youngster they will see quite clearly and not appreciate the need for glasses. They will accommodate the extra +2.00D to see in the distance and it will not necessarily cause symptoms. If that eye is elderly and has no accommodation left, distance vision will be blurry without the glasses. If that eye is a young adult, the capacity to accommodate has already reduced so the effort of accommodating to see in the distance, combined with needing more focusing power for a demanding close up job, can start to cause symptoms such as headaches or tired strained eyes.
Myopic eyes have more than +60.00D focusing power. For a +62.00D eye -2.00 glasses are prescribed for clear distance vision. When this eye looks at something close up it will be clear without the need to accommodate however wearing the -2.00 glasses normalises the vision along with the need to accommodate.
However the process of accommodation in a normal eye does not occur alone or independently. As we accommodate to focus, our eyes also converge, turn in and our pupils become small, this gives an image on the most sensitive part of the eye the fovea and provides stereopsis for detailed tasks. These 3 processes are inexorably linked, and occur simultaneously. This is a problem for our longsighted child who is accommodating to see in the distance because their eyes will squint, converge. While their visual system is still developing they suppress the double vision. This leads to a lazy eye. A completely preventable permanent loss of vision.
"...My eyes are at about -3.0 right now. What I was going to do was to find a weak prescription for the computer so that my eyes would be focusing at a distance. Something like a -2.0, just strong enough to enable me to see the computer screen. My hope is to not make my eyes lazy by wearing too strong a prescription when I spend all day at the computer..."
If your eyes are -3.00, then -3.00 is what you said you could see clearly with. It is not just a made up number! Despite your massive amount of knowledge of things optical and clear disdain for my profession, a lot of our training is to never overminus a myope. So even if you say yes its clearer with that lens, there are ways of checking. The red green duochrome and by putting a lens in that we know should blur you a specific amount. These are essential checks for children or learning disabled or confused patients. They also become invaluable for healthy adults who like to treat it as some sort of game, say yes that’s good I can see clearly with that and then decide that that isn’t what they need at all. Actually I want to be quite blurry in the distance so will only wear -2.00, Ludicrous! Wearing your correct prescription will not make your eyes lazy. They will encourage the proper / normal amount of accommodation needed for your computer and make your distance vision clear.