Outflow facility and its response to pilocarpine decline in aging rhesus monkeys
B. T. Gabelt, K. Crawford and P. L. Kaufman
Department of Ophthalmology, University of Wisconsin Medical School, Madison.
Refractive error and total outflow facility were determined by Hartinger
coincidence refractometry and two-level constant-pressure perfusion,
respectively, in 17 rhesus monkeys, aged 5 to 29 years. Maximum
accommodative response to corneal (iontophoretic) carbachol hydrochloride,
baseline outflow facility, and the facility response to strong but
submaximal intracameral doses of pilocarpine hydrochloride all declined
with age. The correlation between accommodative response to carbachol and
facility response to pilocarpine was slightly stronger than that between
age and facility response. Since the ciliary muscle plays a major role in
controlling both outflow facility and accommodation, and since histologic
and videographic techniques demonstrate an age-related decline in rhesus
ciliary muscle excursion induced by topical pilocarpine or electrical
stimulation of the Edinger-Westphal nucleus, the present data support the
hypothesis that an age-related decline in ciliary muscle mobility is
associated, perhaps causally, with an age-related decline in facility and
facility responsiveness to cholinergic drugs.
