(Table 48-2: Events that Alter Intraocular Pressure)
- Equipotent paralyzing does of all the nondepolarizing neuromuscular blocking drugs directly lower IOP by relaxing the extraocular muscles.
- Intravenous (IV) injection of succinylcholine (SCh) transiently increases IOP by about 8 mm Hg with return to baseline in 5 to 7 minutes (reflects the cycloplegic action of SCh and is not reliably prevented by pretreatment with nondepolarizing muscle relaxants or IV administration of lidocaine).
- It is no longer valid to recommend that SCh be used only with extreme reluctance in ocular surgery (any SCh-induced increase in IOP would be dissipated before surgery is started), but SCh is not the ideal drug for penetrating ocular wounds.
- SCh may interfere with interpretation of the force duction (FDT) test used to determine if strabismus is caused by muscle paresis or a restrictive force (need to wait about 20 minutes after administering SCh to perform the FDT).
- In light of the boxed warning issued by the Food and Drug Administration stating that use of SCh in children may rarely be associated with hyperkalemia and cardiac arrest, it should be reserved for emergency intubation or when immediate airway control is needed (reason SCh is typically avoided in pediatric strabismus surgery).