title: The zonula, lens, and circumlental space in the normal iridectomized rhesus monkey eye.
abstract: OBJECTIVE
  To document zonular orientation and suspension of the lens during accommodation, and age-related changes of the circumlental space (CLS) at rest and during accommodation, in living iridectomized rhesus monkey eyes.
  
  
  METHODS
  The CLS was measured in 34 iridectomized eyes of 24 living rhesus monkeys, age 5.7 to 26 years, in the resting and accommodated state, and the orientation of the zonula and suspension of the lens during accommodation was assessed qualitatively.
  
  
  RESULTS
  The nonaccommodated CLS decreased significantly with age in both the nasal and temporal quadrants and tended to do so at a slightly faster rate in the temporal quadrant. The CLS correlated significantly with the accommodative amplitude: the greater the CLS the greater the accommodative amplitude. Multiple regression analysis indicated that age and CLS together are better predictors of accommodative amplitude than is age alone. The zonula appeared taut in the nonaccommodated eye throughout the age range despite the age-related decline in CLS.
  
  
  CONCLUSIONS
  Characterization of age-related changes in the accommodative apparatus may help to model the system for hypothesis testing. The CLS may be an indicator of presbyopia-related processes in surrounding tissues. However, these results do not prove that the width of the CLS, in and of itself, has a causal relationship with accommodative amplitude, or that changes in the CLS play a pathophysiological role in presbyopia.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Wisconsin Regional Primate Research Center, University of Wisconsin, Madison 53792-3284, USA. macroft@wisc.edu
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Croft
authors.forename: Adrian
authors.initials: A
authors.lastname: Glasser
authors.forename: Gregg
authors.initials: G
authors.lastname: Heatley
authors.forename: Jared
authors.initials: J
authors.lastname: McDonald
authors.forename: Timothy
authors.initials: T
authors.lastname: Ebbert
authors.forename: Nivedita V
authors.initials: NV
authors.lastname: Nadkarni
authors.forename: Paul L
authors.initials: PL
authors.lastname: Kaufman
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D006068:Gonioscopy; D032801:Iridectomy; D007908:Lens, Crystalline / Q000502:physiology* / Q000648:ultrastructure; D008022:Ligaments / Q000502:physiology* / Q000648:ultrastructure; D008253:Macaca mulatta / Q000502:physiology*; D008297:Male; D033401:Microscopy, Acoustic