Hello fellow SOxon-er! Just as a note you don't have to be quite so specific on your location... you can change it by clicking on your name (top right) and finding account details
One option is a tumour near the eye making it bulge but actually some pigs do have a smaller eye or a weepier eye sometimes. Or there might be a bit of hayseed or something stuck under a lid causing swelling. Best to get a vet check though - if it is going to be a problem it's usually best for piggy and cheaper for you to catch it early. They will have a good look at her, maybe using some contrast dye, and they will inspect around the eyeball for any redness or inflammation. She's a dark pig like my George and it's often a bit trickier to see what's going on with them - even in a good light!