The sensitivity and specificity of 0.5% apraclonidine in the diagnosis of oculosympathetic paresis.

AIMS To evaluate the sensitivity and specificity of 0.5% apraclonidine test in the diagnosis of oculosympathetic paresis (OSP). METHOD Apraclonidine (0.5%) was administered to 31 eyes, nine with a diagnosis of Horner syndrome (HS), 22 with bilateral OSP caused by diabetes, and to 54 control eyes. All were confirmed with the cocaine test. The effects on pupil diameter and upper eyelid level were observed 1 hour later. RESULTS Apraclonidine caused a mean dilation of 2.04 mm (range 1--4.5) (p<0.001) in the pupils with OSP and it caused pupillary constriction in the control eyes with a mean change of -0.14 mm (range 0.5 to --1) (p<0.05). It caused reversal of anisocoria in all HS cases. Its effects on both pupil diameters and upper lid levels differed significantly between the groups (p<0.001). The mean elevation in the upper lid was 1.75 mm (range 1--4) in the OSP group (p<0.001) and 0.61 mm (range 0--3) in the control group (p<0.001). CONCLUSION The effect of the apraclonidine (0.5%) test on the pupil diameter was diagnostic for OSP and had at least the same sensitivity and specificity as the cocaine test for the diagnosis of OSP.