Hay and eye problems

What type of hay are you using? Is it really hard and crunchy?

It is from a farmer so its the hard stuff

My only advice is to get softer hay, no matter how you store the hay for them in the cage they will still be able to get hurt.

You can build them a hay box. That's what I have for my 2. It's made out of coroplast. I don't know if you can see it too good but it's in the right front corner of their cage. Because it's at face level there is nothing falling down on their faces.

how hard do you pack your hay into it? Could it maybe be difficult for them to pull out because its packed in tightly?

The only eye poke problems I've had with my herd was when I was giving them first cut hay. I now feed only second cutting and have not since had an eye poke problem [in 8+ months]
First cutting is hard and stemmy, much resembling straw; second cutting is mostly the "leaf" of the grass and is much softer and greener. On average it may be slightly more expensive [Where I live it is $7.00 per bale of 2nd cutting versus $4.00 per bale of 1st cutting] but well worth it.

Silverbeat that is very interesting as it co-relates to something in horses...
stalky hay has a lot of lignin laid into the previous cellulose structure - so the plant can hold up the heavy seed heads when they get riper. In horses, a single stomached animal who also can't vomit, this leads to problems with colic (tummy upset and immunity issues)
While lignin is important for the gut flora cellulose is more important - the leafy hay because it acts as water storage in the colon. I don't know if this is the same with guinea pigs...
the other interesting thing and relevant to eye issues is this: the eye is the indicator organ for the function of the liver (chinese medical philosophy) and when hay is stalky - the root is stressed because the leaf is mostly missing and therefore the root is starving. Very basic explanation here, sorry if it is over simplified... but what the plant then does is attract a kind of living fungus (endophyte) which lives in the base of the plant and feeds the root, it is a neurotoxin. It accumulates in the internal organs especially in the liver at first, it can be the cause of unexplained ill thift - losing weight, also conversely of obesity. It might be that the guinea pigs are showing a symptom of stressed hay. Their first symptom being eyes that look as if they have been infected.

So the small extra cost of second cut hay that has good leaf (and therefore no mycotoxin) is very much worth every cent extra. You can store hay for a minimum of two years to kill of first cut mycotoxin. But as much as this is true not all first cut hay has been eaten off prior to the paddock being closed up for hay production. That depends solely on the farmers personal knowledge and ethics... In horses you always tell from the eye first, then sunburn on white noses second if there is a mycotoxin problem going on - the eyes look as if they are mucky and might have an infection, they are also a bit swollen on the medial upper lid near the corner.

Because mycotoxin accumulates in the body it eventually shuts down the neural function of the organs and the animal dies of unknown causes.