The calabar bean as a new agent in ophthalmic medicine

Abstract

{The substance of this paper was read as a communication at a meeting of the Edinburgh Medico-Chirurgical Society, on Ath February 18G3.

The Effects of Physostigmine Sulphate Eyedrops on Human Visual Function

“…The rapid onset and sustained time course of miosis caused by instillation of physostigmine eyedrops and the transient increase in accommodation confirm the earlier reports of Fraser (1863), Argyll Robertson (1863 and Rengstorff (1970). The effect of physostigmine in potentiating voluntary accommodative effort, assessed as the near-point, was also observed.…”

“…He noted that a rapid and sustained miosis occurred which was accompanied by a 'loss of vision' (attributable to defocus of the retinal image) at 30 min after application, but which had returned to normal by 90 min. Douglas Argyll Robertson confirmed his colleague's observations by recording that a constriction of the pupil by 75 % was still present at 12 h after application while the amplitude of accommodation at 30 min was +5 D (dioptres) and had subsided by 70 min (Argyll Robertson, 1863). These effects of physostigmine in causing miosis and accommodation are now known to be due to its action in inhibiting cholinesterase, thus enhancing the action of acetylcholine released from postganglionic parasympathetic nerve processes (Leopold, 1961).…”

The Pharmacology of Physostigmine

“…Physostigmine is extracted from the seeds of Physostigma venenosum. As "ordeal beans" these seeds were used in trials for witchcraft (80) and an early therapeutic use in ophthalmology was described in 1863 (12). The structure of physostigmine (1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethyl-pyrrolo [2,3-b]indo-5-ol-methylcarbamate) was determined by Stedman and Barger in 1925 (251) and its effect in prolonging acetylcholine action, subsequently revealed as mediated through the inhibition of AChE (252), was discovered by Loewi and Navratil a year later (158).…”

An Evaluation of the Effectiveness of Intramuscular Atropine or Homatropine Eyedrops in Preventing the Effects of Physostigmine Eyedrops on Human Vision

“…Miosis was excluded as a contributory factor since pupil diameter remained constricted for long after the restoration of contrast sensitivity. Douglas Argyll Robertson had first demonstrated the effectiveness of ocular instillation of atropine sulphate in reversing the actions of physostigmine on pupil diameter and accommodation (Argyll Robertson, 1863). Antagonism of the systemic actions of physostigmine by atropine was demonstrated by Thomas Fraser (Fraser, 1870) who had previously first described the actions of physostigmine when given ocularly and systemically (Fraser, 1863).…”