Age-related loss of morphologic responses to pilocarpine in rhesus monkey ciliary muscle
E. Lutjen-Drecoll, E. Tamm and P. L. Kaufman
Department of Anatomy, University of Erlangen-Nurnberg, West Germany.
Ciliary muscle topography and connective tissue distribution were studied
by light microscopy in atropinized, pilocarpinized, or untreated eyes from
rhesus monkeys of various ages. With age, the connective tissue ground
plate between ciliary muscle and ciliary processes thickens, while there is
very little increase in connective tissue within the ciliary muscle. With
age, the atropinized muscle becomes shorter and smaller in area while it
remains unchanged in width and position. In pilocarpinized eyes, the
ciliary muscle is shorter, narrower, smaller in longitudinal and total area
(ie, more circular and compact), and positioned more anteriorly than in
contralateral atropinized eyes. These contractile responses to pilocarpine
diminish with age at a rate similar to that for accommodative decline.
According to these topographic findings, physicians seeking the
pathophysiologic characteristics of presbyopia, which occurs in humans and
rhesus monkeys on a comparable relative time scale, should redirect their
attention toward the ciliary muscle.
