[The effect of brimonidine on the pupillary reflex. A pupillographic study in healthy volunteers].
OBJECTIVE
The effect of brimonidine in comparison with acetazolamide on pupillary reflex was investigated in 18 volunteers.


METHODS
Infrared pupillography was performed with white diode light of 200 ms duration to measure pupil diameter, constriction latency, reaction time, constriction amplitude, and relative constriction amplitude. The measurements were performed according to a fixed schedule including a phase without medication to determine the baseline level. Data were analyzed by Student's paired t-test.


RESULTS
Application of brimonidine and acetazolamide led to a significantly reduced intraocular pressure as well as static and dynamic differences in the pupillary reflex. The pupil diameter measurements were significantly smaller after both medications in comparison to baseline. The reduction of pupil diameter after brimonidine led to significantly reduced contraction amplitude and prolonged latency.


CONCLUSIONS
Application of brimonidine leads to significant miosis, which might due to the affinity to alpha(2)-receptors with reduction of noradrenaline release in the synapse. This effect may play a role in a higher decrease of intraocular pressure by increasing aqueous humor outflow in comparison to clonidine and apraclonidine, but further investigations are required.
Dinslage
S
S
Zentrum für Augenheilkunde der Universität zu Köln. sven.dinslage@uni-koeln.de
Strauss
B
B
Jordan
J F
JF
Diestelhorst
M
M
Krieglstein
G K
GK
D000086:Acetazolamide / Q000494:pharmacology*; D000068438:Brimonidine Tartrate; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects* / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D012025:Reflex, Pupillary / Q000187:drug effects* / Q000502:physiology*
D011810:Quinoxalines; D000068438:Brimonidine Tartrate; D000086:Acetazolamide