Sir,

We thank Beare1 for his interest in our article. It must be remembered that our study was originally an audit of handwashing in the general ophthalmology clinic.2 Through this we showed that the holder used in TONOSAFE can act as a reservoir for micro-organisms such as Staphylococcus, transferred there by normal doctor–patient interaction. This transfer was presumed to be via the clinician's fingers from the patient's face, which is a known route of MRSA transmission.3 We also highlighted that this ‘disposable’ product is not truly single use.

TONOSAFE is manufactured and packaged with one holder designed to be used only with 20 disposable prisms (5 holders with every 100 prisms). It has been our clinical observation that these holders are often used greatly in excess of this, and are rarely disinfected between cases, clinics, or even overnight. This is probably because disposable devices should not require cleaning, as they are, by definition, single use. The idea for our study was generated by the multiple colonies and variety of micro-organisms grown following random plating of one such holder. It was in this context that we suggested cleaning with alcohol wipes between patients to remove the micro-organism load from the holder. It could be argued that these results can be replicated by swabbing any equipment used in regular ophthalmic examination.4 In keeping with surveys of the normal ocular flora, we made it clear in our article that these micro-organisms were unlikely to be of pathological significance in the healthy patient.5, 6

Nevertheless, we thank Beare for his helpful comments regarding cleaning and the theoretical risk of prion transmission. Hopefully, our study has indirectly raised the issue regarding overuse of the TONOSAFE holder and, in doing so, helped to prevent continuation of this practice.