Originally posted by Loadstone
View Post
Another phenomenon I have seen, related to hypertension I have heard, are very bright streaks like shooting stars that cross the visual path and leave a fading trail. My father complains of these as well.
But the most disturbing optical action I have experienced was during a period of serious sleep deprivation and eyestrain. Even after a few hours sleep the problem persisted and I imagined that it could have been related to some blood related event in the visual cortex. In the middle of my field of vision a section of imagery would become inverted - it was there regardless of which eye was closed and prevented any normal focus. The area observed was only a small fraction of the overall field and would represent the diameter of a dime on my monitor three feet away. But it was very problematic. Even after 3 hours sleep, it was still there. It took a full 10 hours of rest before it was remedied. In addition to the inverted section, the boundary between that section and the surrounding normal vision was skewed with radial color streaks and out of focus blurs. Evidently, it had something to do with that portion of our vision we call the 'center' of focus.
Another strange thing I have experienced during continuous staring, is that if the eyes are kept very still and centered on the same image, eventually the image will fade away. In some cases the image will alternate between one eye and the other eye. Each fading away in its turn. This also seems to be preceded by a measure of tunnel vision. I concluded that this is a natural response to an unchanging image where the eyes do not transmit the repeated values to the brain until queried to do so. When the brain encounters what seems to be a failure it will initiate steps to test that failure. A similar thing happens with our ears. If the ears seem to stop functioning, the brain will vibrate the drum and initiate a ringing as a type of calibration. This is most noticeable in very quiet environments or environments with a lot of white noise. I recall there was one girl whose ear rang so loud that her sister could hear it sitting next to her during piano lessons. Here is a different article on the same topic:Sign in to read: Our ears may have built-in passwords - tech - 13 April 2009 - New Scientist
Comment