What does the axis do on your prescription?

Question

mine's right: 158

left: 162

what does the axis actually do?

Answer 1

The axis of an astigmatism prescription defines where the power is located in the lens.  Think of it like this.  Astigmatism means that your eye is shaped like a cylinder to some degree.  If you look at a drinking glass sitting on a table you will notice that there is no curvature to the part of the glass going straight up and down.  The most dramatically curved part of the glass, though, is positioned horizontally on the glass.  

The axis of a cylinder is the direction which has no curvature whatsoever.  The curvature of the glass rotates around the axis of the cylinder.  So the axis of the cylinder on the drinking glass would be vertical (located at 90 degrees).  If you were to take the glass and tip it 20 degrees to the left then the axis of the cylinder of the glass would be located at 110 degrees.  

Now think of the eye like this.  If the shape of your eye is somewhat cylindrical in nature then there will be a direction on the surface of the eye which has the least amount of curvature.  This would be the axis of your astigmatism.  So when you see an axis written on a prescription that tells you where the optician will grind the axis of your prescription in the lens to offset the axis of the cylindrical shape of your corneas.  

I know this was probably confusing but hopefully it made some sense.

Answer 2

The axis is just the direction that your astigmatism correction is at in your lenses.

Kind of like the face of a clock...but instead of 60 minutes, there are 180 degrees that your lens is divided into.

So, your correction is placed along those meridians to focus light in that one specific direction onto your retina.

It could get more complicated , getting into the 90 degree right angles to it as a secondary focal point...but you probably don't need to know that part...