Get your cute rabbit to the vet ASAP! My Trix had this for the first time in 11 years, and we found it was an ulcerated cornea. It is most likely needing an antibiotic eye drop.
Well my last bunny when we got him had it and it settled down because I used some bit nice hay and I hm forgot with new bunny so I removed it now and wonders is there a way I can clean it easy to see if it stays away?