Lid retraction is caused by?
Correct answer : A. Apraclonidine
Both brimonidine and apraclonidine can cause lid retraction. But it is much less frequent with brimonidine.
Ref: KDT 6th p146
Apraclonidine – It is a polar clonndine congener which does not cross blood brain barrier, but applied topically (0.5-1%) it lowers intraocular tension by ~25%. It decreases aqueous production by primary α2 and subsidiary α1 action in the ciliary body. Itching, lid dermatitis, follicular conjunctivitis, mydriasis, eyelid retraction, dryness of mouth and nose are common side effects.
Brimonidine – This recently introduced clonidine congenere is more α2 selective and more lipophilic than apraclonidine. It lowers intraocular tension by 20-27% by reducing aqueous production and by increasing uveoscleral outflow. Ocular side effects are similar to, but less frequent than with apraclonidine. Because of weaker α1 action, side effects like mydriasis, eyelid retraction, conjunctival blanching-hyperemia are less prominent, but dry mouth, sedation and small fall in BP have been noted.