That sounds promising.
Are you sure its not foreign object /grass seed or something?
Has he had his teeth checked, sometimes accesses can cause eye bulges/problems.
One of my girls had a bad eye, she hadpain killers & eye drops &the eye hadn't cleared up after 2days so I took her back as the eye was cloudy &and a bit bloodshot.
When I went back the vet had a good look &still couldn't find a problem. She was just about to go back in her carrier &I spotted a green fleck in her eye.
It was a grass seed had got lodged in her eyelid &worked its way around the back of the eyeball. The vet &I managed to get it out &I was to give her eye drops for at least another 7-10days &go back in a few days if still no better.
Luckily she improved quickly when the seed was removed &was fine afterwards.
I think it was Tiacil drops or possibly fulcalthmic (sp?) drops -although these are now under a new name that I can never remember!
Please enquire about paying in instalments. A lot of vets are good at helping where they can&offer this as a compromise for owners.
Try phoning Anton vets as suggested &see if they can advise on costs,treatment &instalment payments to make things easier for you.
I think he's more of a specialst vet than vets for pets. He would probably have more experience &success rate with eye removals if needed anyway.
Eye removals aren't the end of the world &guineas still have a good quality of life by the sounds of it from other members on here going through it.
It would be such a shame for you to lose him just because of his eye problem.
Healing vibes for your little man &speedy recovery. Xx