aetiological factor as the upper incisors were most affected in our patient. 5 When prescribing oral tetracycline for the treatment of blepharitis in adult patients, it is important to advise on oral hygiene measures and on avoidance of sunlight to minimize staining of teeth. Patients should also be reassured that the stain may be removed with abrasive cleansing by dental surgeon. The evidence for the use of face-masks in surgery generally is poor, with no effect on theatre air bacterial counts 3 and no effect on wound infection rates in a major randomised controlled general surgical trial. 4 Culture plates placed around the patient during cataract surgery without masks have been shown in one study to have increased bacterial cell counts, 5 but there are no prospective studies of face-mask use and PIE. It would be surprising to find a greater effect from mask use in the prevention of PIE than pertains in general surgery, given that the majority of PIE organisms are presumed to originate from the patients' conjunctival flora. ReferencesWhere the evidence for benefit is uncertain, it is appropriate to assess adverse effects. Theatre masks increase condensation on operating microscopes and may impair the surgeons' view. Masks may rub on the face, thus displacing facial skin squames onto the operative site. Unnecessary use is inconvenient, wasteful, and impairs communication. In the absence of direct evidence of harm, we consider it reasonable to continue our current practise of not wearing face-masks in theatre.

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