Ocular interlimbic distance. A new method of monitoring muscle relaxation during anaesthesia.

Measurement of the ocular interlimbic distance (OILD) with a vernier caliper has proved a useful method of studying the reduction in muscle tone caused by general anaesthetic agents and non-depolarising muscle relaxants. The depolarising muscle relaxant, suxamethonium, has a special effect on the extraocular muscles which can be exploited to monitor the incremental use of this drug and to assist in the management of suxamethonium-apnoea in patients with atypical pseudocholinesterase.