Normal near sighted and far sighted is an out of focus situation like a pair of binoculars. Its a mater of changing the focal lenghth to get the focus right. Astigmatism is more complicated. Somtimes it's just the shape of the eye cousing one side of the focal pattern to be different than the rest. It can be the cornea is not a perfect cone but distorted. Regular lasik can add some correction to the eye to compensate for the non perfect shape of the eye. Custom lasic reads the small variations in a cornea astigmatism with a detail topographical map of the cornea. The custom takes a map and makes lots of cuts to get the cornea as near perfect as it can. Somtimes the eye is basically too flat and they can't remove any of the eye. Somtimes your cornea is just too thin and thats why they do an actuall cell count of the thickness. We have ways to correct that also but it basically involves cateract surgery which is the removal of the lens inside your eye and replacing it. Two lens in the eye. One is the cornea and the other is the lens behind your iris. If the cornea is too far out then you go to the other lens. The reason you blink to gain focus is because Astigmatism contact is weighted on the bottom. Your eye may need more correction on one side so thats why they are weighted. The thing about glasses or contacts is they only give a basic corrrection to the focalness of your eye but with lasic or custom lasic they map the eye with so much more detail and digitally manipulate the info to feed into the laser. Regular lasic also maps they eye but with a regular old cornal topographer. It shines rings of light on your eye and looks at the reflection. If the reflection comes back distorted then thru progrming it knows how much and where to trim you eye to better focus it. I used to work on those and there is not much more to them than that. The problem with your eyes you most lickly were born with. Your brain only developed the capacity to define what it saw. So if you correct it then yes you will send your brain much more detailed information but whether or not your brain can use it is a crap shoot. Thats why they ussually won't guarentee steller results with astgmatism. It's better than contacs or glasses but to get the perfect vision you think you are paying for then all bets are off. Thats the problem I have. All the custom correction in the world won't corect the fact that the brain only developed enough for a fuzzy picture. It's like not having as many camera pixels. So feeding it a better image thru a better lens will only help so much. This is why it's so important to get little kids eyes checked. If they have astgmatism then make sure they were gasses even if you have to strap them on.
