DFFA and keratitis: The presence of the icaA and icaD genes (involved in the production of exopolysaccharide N-acetyl-glucosamine) and IS256 exhibited a low frequency in the isolates of the two sources of isolation; which it was according to S. epidermidis isolates from keratitis [15] and also icaA gene was not useful for discriminating between the isolates of keratitis from the healthy conjunctiva isolates [18].