John,

This material can be a problem at this power, likely aggravated by improper lens
positioning and/or waves and flaws in the grind near the central area of the
lens. Ask the optician to mark the distance optical centers and draw a cross at
each center. Look straight into a mirror with your nose pointed right at the
center of the mirror. Try to get at least a couple feet away. Cover each eye
(you must not move your head right or left) and note the position of each center
in relative to the pupil center. The center of each cross should be slightly
nasal, about 1mm, with the vertical position about 3mm to 5mm below the pupil,
The bottom of the frame should be tilted in towards the cheek. If all is well,
and there are no grinding errors, then a less dispersive material will minimize
or eliminate the off-axis blurring. If impact resistance is a priority then
choose Trivex, if not try Spectralite. Regular cr39 plastic will also provide
excellent off-axis vision, is less expensive, with a thicker edge and increased
weight. I would also recommend coated optics (anti-reflection).

Hope this helps
Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
robopt@execpc.com
~~~~~~~~~~~~~~~~~~
"If a million people believe a foolish thing, it is still a foolish thing."
-  Anatole France

I think the grind, etc is fine.

I probably should stick with cr39 in the future as impact resistance is not
an issue.

Thank you.

I had this same experience with two different PAL's.  The first
ones were from Lenscrafters and I returned them, because I could only
see clearly out of one spot of the lens just as you describe.  My
current PALs are Varilux Comforts (same prescription as the other
ones) and these give me a nice wide distance view over the entire
top half of the lens.

The first PAL's also showed quite a bit of swimming effect.  The
new ones don't have this effect at all that I am aware of.

I believe that the cause of this is either cheap lenses, bad fitting,
or possibly both.