Does topical flurbiprofen affect the pupillary response to acetylcholine?

Effect of Flurbiprofen on Acetylcholine-Induced Pupillary Contraction

Preoperative treatment with topical nonsteroidal anti-inflammatory agents such as flurbiprofen (Ocufen) is used to maintain pupil dilatation during cataract surgery. Flurbiprofen maintains pupil dilatation by inhibiting release of prostaglandins and other modulators of surgical miosis. Some reports suggest that these agents may reduce the miotic effect of intra-operative acetylcholine (Miochol). It is hard to explain this effect unless there is a pharmacological interaction between the two drugs. This study aimed to investigate the possibility of a direct interference by flurbiprofen with the action of acetylcholine on the pupil sphincter.

Iris tissue of seven cadaver eyes were isolated and maintained in an organ bath containing Kreb's solution. Pupil contraction force induced by acetylcholine was measured in the presence and absence of flurbiprofen. Acetylcholine produced a mean pupillary contraction force of 52.4 × 10–3 N. When it was added to the organ bath in the presence of flurbiprofen the mean contraction force was 50.6 × 10–3 N (paired t-test P=0.68).

This study does not find any evidence to suggest that flurbiprofen reduces the pupil sphincter contraction that is induced by acetylcholine. It is likely that the apparent reduction in miosis is due to factors other than the mechanism of action of acetylcholine on the sphincter pupillae.

A pre-operative mydriatic regime using a single application of tropicamide Novel Ophthalmic Delivery System and guttae phenylephrine 10%

Tropicamide Novel Ophthalmic Delivery System (NODS) and guttae (g.) phenylephrine 10% was applied once, 2 hours before cataract surgery, as an alternative to our standard pre-operative regime of g. cyclopentolate 1% and g. phenylephrine 10% used four times before surgery. The two treatment groups were compared using a randomised, prospective, observer-masked study design. The horizontal pupil diameter was significantly smaller using the new regime but the per-operative decrease in diameter was not significantly different, suggesting that surgical miosis was not influenced by reducing the number of mydriatic applications. There was no difference in the subjective grading of the pupil, suggesting that adequate mydriasis suitable for cataract surgery was obtained using the alternative regime. No major complications were documented in relation to the use of NODS. We discuss why less intensive mydriasis is likely to be as efficacious and describe its potential advantages.