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It does sound like the shampoo probably burned his corneas. We can see pretty severe ulcers to the entire front of the cornea when this happens.
To treat, you really need to get him seen by a vet. Prescription drops that have an antibiotic, like Neo-Poly-Gram, is needed. I also usually put them on an anti-inflammatory med for the pain. This may be topical (Flurbiprofen) or oral (Rimadyl). They are usually much more comfortable within 12-24 hours of starting the meds. They heal completely within 7-10 days.
From home, the only thing that will help is a saline rinse. This can help soothe the corneas. You want to use saline as opposed to water that will dry them out more.
I hope this helps, let me know if you have any other questions.