A blister or pustule.
A bubble, as in water or other fluid, or in a substance that has been fluid, as glass.
Doctors make a small hole toward the front of the eye to drain out extra fluid, which is filtered through a "bleb" - a blisterlike bulge -- and eventually absorbed by the blood stream.
He could not breathe on his own, but neither could he tolerate breaths the way they should be delivered, all at once and then out again, because that bleb was expanding and would eventually burst, popping the way a birthday balloon does when the party is ended and the guests have dispersed, violently shredding beyond all hopes of repair.
It's that scanner that peeks under your clothing, creating a ghostly but realistic image of your naked body, accurate down to every curve, knurl, protuberance, carbuncle, wen, bleb, wart and wattle and garfunkel.
The wound itself showed as a tiny scarlet spot on the sclera, a small conjunctival bleb above it.
The word 'bleb' is probably an alteration of 'blob'.