Sir,

We read with great interest Wertheim et al's1 article on a new minim technique for diagnostic anterior chamber paracentesis. Although the use of a 25-gauge needle attached to a minim is an ingenious option in cases in which no better suited equipment is available, we would not wish readers to assume that this is the only, nor, in our opinion, the best, alternative to a specifically designed paracentesis pipette such as the O'Rourke pipette.2

Our group has previously described our technique for diagnostic anterior chamber paracentesis at the slit lamp. In that series of 70 procedures, 48 were performed with a 27-gauge needle pre-fixed to a 1 ml insulin syringe (BD Medical, Oxford, UK), rather than a specifically designed pipette. This was found to be safe, with no serious complications using either instrument.3 Usage of the insulin syringe technique now predominates in our specialist service, with 56 of the 57 paracenteses performed by us in the last year utilizing this technique. As with the minim technique, the equipment required for the insulin syringe technique should be present in any ophthalmic department.

There are significant advantages of the insulin syringe technique that help make this procedure as safe as possible: a prefixed needle (with no risk of detachment or slippage), a measurable chamber (enabling monitoring of the volume withdrawn), and a slow predictable response to withdrawal of the plunger (vs a rapid fluid shift for a very small change of pressure on the bulb of a minim). The disadvantage of the insulin syringe technique is that, similar to the minim technique, it has a longer needle than the O'Rourke pipette (½″ for the insulin syringe vs ¼″ for the O'Rourke). We do recognize that the insulin syringe technique is assisted by having an assistant to withdraw the plunger under the supervision of the operator, whereas this is not necessary with dedicated aqueous pipettes such as the O'Rourke or the minim technique.

Alongside welcoming the resourcefulness of the minim technique and recognizing its potential usefulness, we would propose that in general a specialist paracentesis pipette such as the O'Rourke or a 1 ml insulin syringe is likely to be the safer option.