CAD), prophylaxis is absolutely contraindicated in adults. Considering that many elderly ophthalmologic surgery patients have significant comorbidities associated with aging (ex. Prophylaxis with medications (atropine, glycopyrrolate) or retrobulbar block (4) may be effective in children but has not been effective in adults. The OCR most commonly occurs in children undergoing strabismus surgery but can occur in adults as well. The OCR is not suppressed by general anesthesia, and occurs secondary to globe pressure, traction on the extraocular muscles or conjunctiva, and sometimes retrobulbar blocks. Stimulation of the eye leading to cardiac dysrhythmias, most commonly bradycardia but almost any rhythm, including AV block, bigeminy, PVCs, V-tach, or aystole can occur. Oculocardiac Reflex (trigeminal afferent, vagal efferent) Intravenous anesthetics, with the possible exception of ketamine, also decrease intraocular pressure. Inhalational anesthetics decrease intraocular pressure due to decreased blood pressure (reduces choroidal volume), relaxation of the extraocular muscles, and pupillary constriction (facilitates aqueous outflow). Classically there has concern that this increase in IOP could lead to extrusion in open eye injuries, however this has never been substantiated – there is now at least one report IV SCh administration which did not lead to extrusion. Succinylcholine and IOPīy an unknown mechanism (initially thought to be due to extraocular muscle contraction, however now there is evidence to the contrary (2), SCh increases IOP by 5-10 mm Hg for 5-10 minutes, with onset 2-4 minutes after administration. IOP can be increased with hypoventilation, hypoxemia, or increased central venous or arterial pressure. IOP can be lowered with hyperventilation, lowered arterial or central venous pressure, or hypothermia. When the globe is open (either during surgical procedures or secondary to trauma), the globe is highly sensitive to forces which would normally raise IOP – in the open globe, IOP cannot be raised, and the eye responds by draining aqueous fluid or extruding vitreous through the wound, the latter of which can permanently worsen vision.
IOP is generated by ocular muscle contractions and is partially-dependent on scleral rigidity (which increases with aging), intraocular content (lens, vitreous) rigidity (also increases with age), and venous congestion. Normally 10-22 mm Hg, varying 1-2 mm Hg per beat (HR) and 2-5 mm Hg over the course of the day (highest in the AM). (1) Ocular Physiology Intraocular Pressure While ophthalmologic procedures are not particularly dangerous in and of themselves, many patients are elderly and have multiple comorbid conditions.
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