Effect of pretreatment with propranolol on intra-ocular pressure changes during induction of anaesthesia

It is well documented that intra-ocular pressure (IOP) increases following the administration of suxamethonium and also after laryngoscopy and intubation. It is possible that there may be a final common pathway mediated by beta adrenergic transmission which leads to this pressure rise. If so, this mechanism should be inhibited by beta adrenoceptor blockade. Pretreatment with propranolol prevented a significant rise in IOP during a thiopentone, suxamethonium, intubation induction sequence. The change in IOP was even more pronounced during a thiopentone, alcuronium, intubation induction sequence as the base-line IOP was not regained, but there was significant cardiovascular depression. In both these methods the IOP did not remain stable; there was an initial reduction followed by a rise in pressure. Whether these changes in IOP are clinically important remains an open question.