Generally the contact gives you good vision only through the portion of your
pupil that it covers. If that's 75% of the total area of your pupil, you get
a crisp image from 75% of the rays, but it's surrounded by a blurry image
contributed from the 25% bypassing the contact. This haze would come and go
as the lens moved in and out of place. It would probably be associated with
"flare", a semicircular reflection produced by the meniscus at the lens
edge.

You didn't describe variability, or flare when the lens moves, so poor
centration may not be the problem.

You haven't said whether the haze disappears _immediately_ after switching
to glasses. That's important if you're worried about edema.

Corneal edema (CE, or CCC for Central Corneal Clouding) used to be very
common with PMMA contact lenses, and it always persisted more than a minute
or two after removing contacts.

CE would likely be spotted in the slit lamp if it were present. It stands
out. But probably you weren't examined at night, after several hours of
wear. CE would increase as the day goes on and start reversing soon after
you remove lenses.

If your haze persists after switching to glasses, another possibility is a
GP footprint, a temporary impression of the lens edge pressed into the
corneal epithelium, from a lens that sticks off-center and doesn't move
enough.

So, if the haze goes away after switching to glasses, it's likely buildup or
surface contamination.

Consider using a Q-tip soaked in cleaner, spinning it gently against the
back surface of the contact once a week or two. Sometimes your cleaning
routine misses that surface if your fingers are too big, etc. Make sure your
lenses stay wet after massaging with conditioner. If it beads up, there's
oil on the lens.

-MT