PubMed ID: 2211015
Author(s): Crawford KS, Kaufman PL, Bito LZ. The role of the iris in accommodation of rhesus monkeys. Invest Ophthalmol Vis Sci. 1990 Oct;31(10):2185-90. PMID 2211015
Journal: Investigative Ophthalmology & Visual Science, Volume 31, Issue 10, Oct 1990
After unilateral total iridectomy, maximum accommodation inducible by corneal iontophoresis of carbachol in rhesus monkeys was approximately 40% less in the iridectomized than in the contralateral untouched eyes, irrespective of age. Ultrasonographically measured anterior chamber shallowing and lens thickening were also less in the iridectomized eyes. Neither submaximal accommodation induced by intramuscular pilocarpine infusion nor maximum accommodation inducible by midbrain stimulation differed in iridectomized and intact eyes. The authors hypothesize that at maximum cholinomimetic drug-induced contraction, the iris sphincter muscle pulls the ciliary body farther forward and inward than does maximum ciliary muscle contraction alone, allowing additional rounding of the lens and, consequently, additional accommodative power.