I don't know exactly about ur dog real condition. But I guess that he got conjuctivitis, it is an inflamation on eye's mucous/conjunctiva layer. There'r some causes;local inflamation or from inside his body system. Dog should get deworming pil every 3 months orally. If u haven't gave any deworming pil yet, may be ur dog got worm inside his stomach and it signed on his eyes dirt. for the eyes i suggest u give gentamycin eye ointment or chlorampenicol eye ointment twice a day. and if u find redness on his eye ball u can also give cendotropin eye drops. Wish it help u.