While medical scientific knowledge pertaining to bacterial adhesion to biomaterials has become a rapidly growing field in most areas of medicine, its significance in ophthalmic infections has not been emphasized. Corneal bacterial ulceration in patients wearing extended-wear contact lenses has become a problem of epidemic proportions. The designation of the contact lens itself as a suitable substratum for bacterial colonization and as a source of subsequent inoculum to compromised epithelial cells are important factors in the pathophysiology of corneal ulcer formation. We demonstrate polysaccharide- (biofilm-)mediated adhesion to two ophthalmic pathogens (Pseudomonas aeruginosa and Staphylococcus epidermidis) to the surface of a typical extended-wear contact lens in vitro using cytochemistry and scanning and transmission electron microscopic techniques. This interaction between the biomaterial and bacterial organisms, which represents a favorable self-protective environment for propagation and inoculation, is a previously overlooked area of importance in the mechanism of corneal ulceration associated with hydrophilic (soft) contact lenses.