To the Editor.
—Some points in the interesting article by Wolf et al1 in the March 1985 Archives require clarification.
—The temperature, pressure, and humidity of the injected gas are likely to differ from that of the gas subsequently withdrawn from the eye. These factors are all likely to influence the measured volume of gas withdrawn. Therefore, some estimate of the expected error should be mentioned.
—Wolf et al extrapolate their findings to give a possible explanation of Abrams et al's2 high incidence of postoperative ocular hypertension. Surely, the results indicate just the opposite. Once N2O anesthesia is terminated, the patient will rapidly exhale his dissolved N2O, with consequent N2O diffusion out of the intraocular gas bubble, thus tending to lower the postoperative gas bubble size rather than increase it. I agree that the converse is true preoperatively, but, surely,
Thaller VT. Effect of Nitrous Oxide on Gas Bubble Volume. Arch Ophthalmol. 1985;103(9):1272. doi:10.1001/archopht.1985.01050090022006