This study evaluated the effect of
sodium naproxen (a reversible competitive inhibitor of
cyclo-oxygenase) and
phenylephrine (a
mydriatic alpha-
adrenergic agent)
eye drops in maintaining
atropine mydriasis in the rabbit after paracentesis. Moreover, to assess the influence of these treatments on vascular and cellular inflammatory responses in the rabbit eye, several biochemical parameters were considered. Anterior chamber paracentesis significantly reduced
atropine-induced
mydriasis and a parallel elevation of
proteins, polymorphonuclear leucocytes (PMNs),
prostaglandin E2 (
PGE2) and
leukotriene B4 (
LTB4) levels in the secondary aqueous humour (obtained 120 min later) was observed. A significant increase in PMNs in the aqueous humour and a parallel increase in
myeloperoxidase activity, a measure of PMN infiltration, in the iris-ciliary body were detected.
Atropine-induced
mydriasis was maintained in rabbits treated with either
sodium naproxen or
phenylephrine eye drops. However, only in the former group were the inflammatory parameters significantly reduced, with the exception of aqueous
LTB4 levels. The inhibition of the
protein influx in the aqueous humour and of the
miosis produced by
sodium naproxen can be related to the high
drug levels in the aqueous humour that were effective in inhibiting the
cyclo-oxygenase pathway of
arachidonic acid metabolism, whereas the effects on PMN infiltration appear to be independent of significant release of the potent chemotactic agent
LTB4, synthesized via the
5-lipoxygenase pathway.