Hi and welcome
Eye injuries in guinea pigs are quite common; especially hay pokes. They deteriorate very quickly and often ulcerate (produce infectious gunk). The sooner you can have them seen, the better because they also heal the better less bad they get. In the UK, eye injuries are seen as a priority and will be squeezed in at a vets as soon as possible.
Any injury should be ideally seen within 24 hours; if there is blood, then this counts as an emergency and may need a trip to the out-of-hours vets. You can eiher google for out-of-hours vet services or get the contact number from your vets' phone message when the clinic is shut.
Since guinea pig eyes are just like dog or cat eyes and require the same treatment consisting ideally of antibiotic eye gel or drops, lubricant and an analgesic (anti-inflammatory and painkiller), speed comes before specialisation - see the vet who can squeeze you in quickest, whether that is a general vets or an exotics one.
Any gel you gently dab on the eye and for any eye drops you gently pull the lower lid down and aim the drops into the gap. If necessary, distract the piggy with their favourite veg and assert your authority with a spot of piggy whispering. Please always wait at least half an hour between the antibiotic gel/drops and any lubricant whether that is a vet brand or plain carbomer tear gel to ensure that the antibiotic is fully absorbed and cannot be washed away. You should see a noticeable improvement latest after 2-3 days.
Thankfully, most hay pokes heal well without complications if seen promptly. The eye can look worse before it gets better, especially if healing blood vessels appear temporarily to bring oxygen to the wound in the eye. Please always continue medicating until the last of cloudiness has fully disappeared.
Who is the Boss - Your Guinea Pig or You?
If it is any consolation to you, I've been to my local general vets this morning with a piggy of mine that had some hay stuck under her lid (which I was able to remove yesterday) but also has been found to have a small ulcerating perforation of the cornea, so I am following the same tips in this post myself right now.
All the best!