Pannus

Aweb-like patch of grayish membranish tissueusually covering the upper half of the cornea,making it almost opaque. It is usuallv causedby the rubbing of roughened or granulated lidsover the cornea and results in the eifort ofnature to protect this membrane.

Source: Ophthalmic Dictionary including pronunciation, derivation and definition of the words used in Optometry and Ophthalmology by James J. Lewis, Oph. D. Professor of Optometry in the Northern Illinois College of Ophthalmology and Otology, Chicago.