CYLINDRICAL PRISM STABILIZED LENSES


With a hydrogel lens the cylinder can be generated on either the front or back surface.

The cylindrical power and axis is 
specified in the same way as with 
spectacles except the reference 
for the cylinder axis is the 
base-apex line of the prism.  When 
specifying the axis it is assumed 
that the base-apex line is in the 
90 degree meridian.

On the eye the base-apex of the lens 
may rotate away from vertical 
meridian.  During the fitting this rotation 
must be taken into account when the 
lens power is ordered.