The effect of phenylephrine hydrochloride on the resting point of accommodation.

Previous models for ocular accommodation have suggested a dual sympathetic/parasympathetic innervation to the ciliary muscle. Such models would predict that sympathomimetic drugs should change the resting point or dark focus of accommodation. The effect of an alpha-adrenergic agonist (10% phenylephrine hydrochloride) on accommodation was examined; the results show a decrease in the near point of accommodation, without a change in the resting point of accommodation. These results suggest that the accommodative state of the eye is not the result of a simple balance between sympathetic and parasympathetic innervation as proposed by previous models of accommodation.