We first have to identify what kind of distortion you are referring to. A photo will be great.
Originally Posted by La Fontaine
There are general 3 kinds of distortions associated with UWAs, perspective distortions, keystone effects and curvilinear distortions.
From the way you've described, I'll hazard a guess and think that it was perspective distortions. This is inherent in UWA design and cannot be corrected. This is the best example I can find in the office. Take a look at the floor tiles at the bottom of the frame and the tables in the near distance. They are being skewed out of proportion and shape. That is perspective distortion associated with a UWA and they cannot be corrected. Their impact can however, be minimised with careful framing. Personal, I'd like to go wild on these because they can make a composition look more dynamic.
About tilt/shift lenses.....
They are used to correct keystone effects which are commonly seen in architectural photography where you need your vertical lines to be straight without cropping out bits or parts of your subjects.
As you can see, the photo was corrected with with a tilt/shift lens. If you were to pay attention to the top of the building, geometric distortion is still pretty evident. the building is being skewed out of shape by the UWA tile/shift. That's inherent in the lens design.