Abstract

Six patients with intraocular hypertension received 0.5% timolol or saline uniocularly with saline to the other eye, and the intraocular pressure was measured by applanation tonometry at 0, 30, 60, 120, and 240 minutes. Falls in pressure were seen in both the timolol treated and consensual eyes. The same experiments were conducted after pretreatment of the consensual eyes with guanethidine 5%. The consensual ophthalmotonic reaction (COR) to timolol administration was blocked by pretreatment with guanethidine. Three out of four patients with Horner's syndrome also showed a reduced COR in the affected eye after timolol administration to the normal eye, suggesting that the COR is mediated by a nervous reflex with the efferent limb in the sympathetic nervous system.