--------- Quoted Kelly ----------
One odd thing about my prescription is that I had a strange distortion
in which things that should have been square or rectangular looked
slightly trapezoidal. I'm told this is due to differences in power and
it seems that I've adjusted to that ok. As you may expect, when I take
the glasses off I now notice the trapezoid in the opposite direction.
(In other words, with glasses I at first saw edges on the left of my
monitor as taller than the right side. Now that I've adapted somewhat,
it looks close to normal with the glasses on. However if I take them
off, the right side of the monitor now seems taller than the left
side.) No one seemed to have heard it described that way from any of
their patients at either clinic or store.

--------- Quoted William Stacy ----------
Very common, especially if the astigmatism Rx is slightly off axis, or
stronger than necessary. Can be normal, but if bothersome, my modus is
to recheck axis and reduce cylinder.
-----------

I am curious to hear what you ended up doing to correct the trapezoidal shape distortion. I just got my first pair of glasses and have the exact same problem.

I may have caused this problem myself by being such an uber cheapskate. I ordered my glasses online (for $8.95+$5shipping) but the OS-CYL on the glasses I got is .25 off from my prescription. I have my doubts that that is the cause of my problem though because I'm pretty sure my o.d. said I could really use up to a 3.5 correction but he was giving me a weaker OS-CYL prescription because my brain would have trouble adjusting as a first time glasses wearer. The glasses are great otherwise, super clear, it's just that my monitor is now 15% taller on the left side. Sad

Anyhow, I would like to get someone's opinion on if I should pay for a recheck or just go ahead and order a new pair to get the correct prescription.

Prescription:
OD-SPH: -.50
OD-CYL: -1.25
OD-AXIS: 90
OD-ADD: 0
OS-SPH: -.50
OS-CYL: -2.25
OS-AXIS: 1
OS-ADD: 0
PD-Pupillary Distance: 64

Glasses:
OD-SPH: -.50
OD-CYL: -1.25
OD-AXIS: 90
OD-ADD: 0
OS-SPH: -.50
OS-CYL: -2.00
OS-AXIS: 1
OS-ADD: 0
PD-Pupillary Distance: 64

Thanks for any help!

I have exactly the same problem!
I got my fist pair of glasses 4 days ago from SpecSavers, tests done at VisionExpress.
The trapezoid effect seems to be on the right eye - the left edge of a computer window is longer than the right edge - just by 5% perhaps. But I'm getting dizzy and confused.
I already started to develop the reverse effect in the left eye!

Funny is that I never noticed shape distortion before! I only needed some spherical +0.75/+0.25 to help me read in sharp focus!

How did you solve your problem eventually?