OPTIC-NERVE VASOMOTOR EFFECTS OF TOPICAL APRACLONIDINE HYDROCHLORIDE

Aims - To examine, in vivo, the anterior optic nerve vasomotor effects of chronic apraclonidine hydrochloride in rabbits. Methods - After lo cal treatment in one randomly chosen eye with apraclonidine hydrochlor ide 0.5% over 21 days, the microvasculature of the optic nerve was exa mined in five rabbits using an intraluminal microvascular corrosion ca sting technique. The investigators were masked as to which eye was tre ated. The vasoconstriction near the branching point of arterioles supp lying the optic nerve was calculated as a percentage of the downstream vessel calibre. An average constriction was calculated and compared b etween the treated and the contralateral, untreated, eyes by means of a two tailed t test for paired variables. Constriction values of a tot al of 72 arterioles supplying the optic nerve were obtained for the fi ve rabbits. Results - The average constriction in the treated and the control eyes was comparable (p = 0.96). Conclusion - Chronic administr ation of apraclonidine hydrochloride 0.5% produces no observable optic nerve vasomotor effects in the rabbit eye.