In many cases this swelling amounts to a bleb which may be increased by massage of or pressure upon the eyeball.
bleb, bleb, n. a transparent blister of the cuticle: a bubble, as in water.
c.1600, "blister or swelling," imitative. Also used for "bubble" (1640s), "protuberance on a cell surface" (1962).
A large flaccid vesicle.