Acetylcholine in Cataract Surgery.

ALTHOUGH the use of acetylcholine as a miotic agent in ophthalmic surgery is not new, it has not been widely used in the United States nor has it been readily available. Amsler and Verrey (1949) recorded the rapid miotic effect of acetylcholine instilled into the anterior chamber and suggested its use as a possible therapeutic agent after cataract extraction. Acetylcholine acts directly on the motor end-plate of the sphincter muscle of the pupil to effect pupillary constriction. The activation of structures supplied by post-ganglionic fibres of the parasympathetic nervous system mediated by acetylcholine (parasympatheticomimetic action) is well known. At the Barraquer Institute in Barcelona, where it has been used extensively, acetylcholine was being introduced into the anterior chamber as a routine measure after cataract extraction during the 1962 congress. Schimek (1961) has observed that rapid miosis permits prompt protection of the vitreous face after cataract extraction. Miosis also facilitates the addition of post-placed corneo-scleral sutures by reducing the hazard of iris incarceration by the sutures. Barraquer (1964) reported on a small series in which acetylcholine was used in the anterior chamber after cataract extraction to determine an effective concentration of the drug which was at the same time harmless to the anterior chamber structures. He stated that the 1: 100 concentration was the most reliable and dependable for miosis but the series was too limited to be conclusive. In certain ophthalmic surgical procedures such as cataract extraction or keratoplasty the immediate constriction of the intact pupil is a distinct advantage. In order to determine the most effective strength of acetylcholine for using in the anterior chamber two series were performed using the same premedication and technique with a total of 106 cataract extractions (Harley and Mishler, 1964). Various concentrations of acetylcholine from 1: 1000 to 1: 100 were injected into the anterior chamber and the pupillary size was measured one minute later. The corneas and anterior chamibers have undergone careful scrutiny for any immediate or long-term changes. The results are fully tabulated and include brief mention of some experimental observations (Tables I and II, overleaf).