No way to tell for sure but the most likely thing would be a small cyst of the conjunctiva. You might use artificial tears. If it continues to be a problem see an eye MD for a diagnosis and to drain the cyst which is easy.
JCH DM
Thank you John,
Do you have any idea what was the reason for that bubble..
Thanks
Prasad
just happens, same as cysts elsehwere, very common on the eye.
JHC MD