Amblyopia is blindness from any cause. What we are talking about here is amblyopia ex anopsia, that is blindness without obvious ocular cause - a well-formed eye that doesn't see well. Likely causes are malalignment or significant refractive difference between the eyes. It turns out that vision is learned. If you sew a kittens eye closed and then open it later it will not see. Same thing happens with kids with congenital ptosis. Now it also turns out that alignment of the eyes is also learned to a certain extent. Infants and yoga practitioners can move them independently - they are not yoked together like the front wheels of a car. There is a certain amount of "chicken and egg" problem here because if the eyes aren't aligned one will tend to be suppressed because if it isn't double vision will result. OTH if one eye doesn't see it will tend to drift because it lacks the stimulus of doubleness which keeps eyes aligned in the first place.
Now it gets more complicated. Frequently only the central part of the vision of the deviating eye is suppressed and the peripheral part is fused with the vision of the other eye. This situation is more stable in terms of alignment than cases in which the deviating eye is totally suppressed. Those are the ones that get operated every 5-10 years for increased deviation.
The whole system is pretty malleable in terms of training prior to age 6, iffy from 6-12 and virtually impossible to influence after age 12. No one know why, but it has to do with the same thing that lets you learn a foreign language without an accent if you are young enough. After a certain age that is nearly impossible. To evaluate this report you have to know the age of the patients and whether or not there was organic disease, prior treatment including glasses and surgery and a lot of other variables. Then there needs to be a matched group with another form of therapy.
We are not exactly dealing with
The New England Journal of Medicine here. The first thing you see on the site is an
invitation to visit the LiveScience store. It would appear that the purpose of this
article is to sell something.
The arteries in the retina are
the only arteries directly visible in the human body and physicians have been
looking at them ever since von Helmolzvon Helmholtz
invented the direct ophthalmoscope in 1851.
This is the unit with which your doctor peers into your eye using one of
his own. Unfortunately, due to the intractability
of Snell's LawSnell's
Law less than 10 degrees of retina can be seen. A good explanation of the exam is located
here.here.. Should the doctor use both eyes with an
indirect ophthalmoscope such as is used during retinal surgery considerably
more retina can be seen but the image is aerial and cannot be photographed
directly. Nevertheless a good retinal
camera, taking multiple views which are then pieced together can provide a map
of the retinal vessels. The gold
standard for this sort of thing in diabetes was the Airlie
House Classification developed in 1968.1968.. A modern study modern study might involve 7-field
stereoscopic color photographs to get an accurate map. Accurate results cannot be produced with a
single picture through an undilated pupil in an aging
population suspected of disease. The way
to diagnose hypertension is with a blood pressure cuff. The way to diagnose diabetes is with a blood
test.
"As you start moving forward, inboard portions of the retreating blade see airflow from trailing edge to leading edge."
Same thing happens with a rotary lawnmower. As you push it forward faster and faster the retreating edge moves slower relative to the grass and cuts less efficiently. The opposite happens with the advancing edge. At high ground speeds you get a wavy cut, higher on the retreating edge side. It seems to me it's higher at the extreme edge, not at the middle as would be indicated by the above statement. I think this is because the sideways motion of the blade fore and aft is more efficient in the middle, whereas on the edge there is none.
We are talking here about sex differences which are objective, not gender differences which are not. The link goes to ABC News Online which in turn quotes an article in the Journal of Theoretical Biology. The reporter offers as explanation: "The Sunday Times quoted a specialist in evolutionary psychology as saying it could be because the children of "systemiser" parents appeared to encounter more testosterone in the womb" It is a little difficult to understand how any amount of testosterone in the womb could induce a Y chromosome to appear de novo. It costs $30 to view the original article but the abstract is free. OTH it doesn't indicate any methodology.
This isn't exactly a medical breakthrough. The pre-frontal area has long been known to control higher functions - judgement, abstraction - of which sarcasm is a subset. The interpretation of proverbs is a standard test for its being intact. Unfortunately, this system succumbs to toxic influences before the motor system so that anoxic pilots fly into mountains and drunk drivers crash cars.
Depth perception, the ability to perceive realtive distances, exists to some extent as a monocular function. You can move your head side to side to gain parallax for instance, distant objects are bluer, closer objects overlap distant ones. Stereopsis, which is the phenomenon upon which this screen and 3D movies is based requires 2 eyes. Two input streams have different angles and the effect of 3 dimensions is created in the brain as a cyclopean view. A person with one eye would not see the stream addressed to that eye.
Not too impressed with the research. Reminds me of the flap a few years ago when a study purported to show that leaving the night light on caused the baby to develop myopia. Turned out near sighted mothers see poorly in the dark, tend to leave the night light on, are more likely to have near sighted children. Correlation of factors does not prove causation.
Here we know that myopia alone can produce field defects - either as an artefact of field testing or through peripheral retinal thinning due to increased axial length. Some defects are typically produced by glaucoma and some aren't - no differentiation is made. Where is the score of the equally near sighted people who don't use computers? In the discussion of self selection it is said that the general public doesn't know that myopia is a risk factor for glaucoma, but I would go further back the chain and say that myopia may be a self selection process for computer users. After all, the gene preservation for myopia is highest in those societies furthest removed from hunter-gathering and computation is the current most distal point
Slashdot Mirror
Amblyopia is blindness from any cause. What we are talking about here is amblyopia ex anopsia, that is blindness without obvious ocular cause - a well-formed eye that doesn't see well. Likely causes are malalignment or significant refractive difference between the eyes. It turns out that vision is learned. If you sew a kittens eye closed and then open it later it will not see. Same thing happens with kids with congenital ptosis. Now it also turns out that alignment of the eyes is also learned to a certain extent. Infants and yoga practitioners can move them independently - they are not yoked together like the front wheels of a car. There is a certain amount of "chicken and egg" problem here because if the eyes aren't aligned one will tend to be suppressed because if it isn't double vision will result. OTH if one eye doesn't see it will tend to drift because it lacks the stimulus of doubleness which keeps eyes aligned in the first place. Now it gets more complicated. Frequently only the central part of the vision of the deviating eye is suppressed and the peripheral part is fused with the vision of the other eye. This situation is more stable in terms of alignment than cases in which the deviating eye is totally suppressed. Those are the ones that get operated every 5-10 years for increased deviation. The whole system is pretty malleable in terms of training prior to age 6, iffy from 6-12 and virtually impossible to influence after age 12. No one know why, but it has to do with the same thing that lets you learn a foreign language without an accent if you are young enough. After a certain age that is nearly impossible. To evaluate this report you have to know the age of the patients and whether or not there was organic disease, prior treatment including glasses and surgery and a lot of other variables. Then there needs to be a matched group with another form of therapy.
We are not exactly dealing with The New England Journal of Medicine here. The first thing you see on the site is an invitation to visit the LiveScience store. It would appear that the purpose of this article is to sell something.
The arteries in the retina are the only arteries directly visible in the human body and physicians have been looking at them ever since von Helmolzvon Helmholtz invented the direct ophthalmoscope in 1851. This is the unit with which your doctor peers into your eye using one of his own. Unfortunately, due to the intractability of Snell's LawSnell's Law less than 10 degrees of retina can be seen. A good explanation of the exam is located here.here.. Should the doctor use both eyes with an indirect ophthalmoscope such as is used during retinal surgery considerably more retina can be seen but the image is aerial and cannot be photographed directly. Nevertheless a good retinal camera, taking multiple views which are then pieced together can provide a map of the retinal vessels. The gold standard for this sort of thing in diabetes was the Airlie House Classification developed in 1968.1968.. A modern study modern study might involve 7-field stereoscopic color photographs to get an accurate map. Accurate results cannot be produced with a single picture through an undilated pupil in an aging population suspected of disease. The way to diagnose hypertension is with a blood pressure cuff. The way to diagnose diabetes is with a blood test.
"As you start moving forward, inboard portions of the retreating blade see airflow from trailing edge to leading edge." Same thing happens with a rotary lawnmower. As you push it forward faster and faster the retreating edge moves slower relative to the grass and cuts less efficiently. The opposite happens with the advancing edge. At high ground speeds you get a wavy cut, higher on the retreating edge side. It seems to me it's higher at the extreme edge, not at the middle as would be indicated by the above statement. I think this is because the sideways motion of the blade fore and aft is more efficient in the middle, whereas on the edge there is none.
We are talking here about sex differences which are objective, not gender differences which are not. The link goes to ABC News Online which in turn quotes an article in the Journal of Theoretical Biology. The reporter offers as explanation: "The Sunday Times quoted a specialist in evolutionary psychology as saying it could be because the children of "systemiser" parents appeared to encounter more testosterone in the womb" It is a little difficult to understand how any amount of testosterone in the womb could induce a Y chromosome to appear de novo. It costs $30 to view the original article but the abstract is free. OTH it doesn't indicate any methodology.
This isn't exactly a medical breakthrough. The pre-frontal area has long been known to control higher functions - judgement, abstraction - of which sarcasm is a subset. The interpretation of proverbs is a standard test for its being intact. Unfortunately, this system succumbs to toxic influences before the motor system so that anoxic pilots fly into mountains and drunk drivers crash cars.
Depth perception, the ability to perceive realtive distances, exists to some extent as a monocular function. You can move your head side to side to gain parallax for instance, distant objects are bluer, closer objects overlap distant ones.
Stereopsis, which is the phenomenon upon which this screen and 3D movies is based requires 2 eyes. Two input streams have different angles and the effect of 3 dimensions is created in the brain as a cyclopean view. A person with one eye would not see the stream addressed to that eye.
Not too impressed with the research. Reminds me of the flap a few years ago when a study purported to show that leaving the night light on caused the baby to develop myopia. Turned out near sighted mothers see poorly in the dark, tend to leave the night light on, are more likely to have near sighted children. Correlation of factors does not prove causation. Here we know that myopia alone can produce field defects - either as an artefact of field testing or through peripheral retinal thinning due to increased axial length. Some defects are typically produced by glaucoma and some aren't - no differentiation is made. Where is the score of the equally near sighted people who don't use computers? In the discussion of self selection it is said that the general public doesn't know that myopia is a risk factor for glaucoma, but I would go further back the chain and say that myopia may be a self selection process for computer users. After all, the gene preservation for myopia is highest in those societies furthest removed from hunter-gathering and computation is the current most distal point