title: Aqueous humor dynamics in the aging human eye.
abstract: OBJECTIVE
  Healthy subjects were recruited to identify normal, age-associated changes in intraocular pressure and aqueous humor dynamics.
  
  
  METHODS
  Normal healthy subjects from two age groups were enrolled in the study: (1) those from 20 to 30 years of age (n = 51) and (2) those 60 years of age and older (n = 53). Intraocular pressure was measured by pneumatonometry, tonographic outflow facility by pneumatonography, and episcleral venous pressure by venomanometry. Aqueous flow and outflow facility were determined by a fluorophotometric technique. Uveoscleral outflow and anterior chamber volume were calculated. Results from the older group were compared with those from the younger group by means of unpaired, two-tailed t tests.
  
  
  RESULTS
  Compared with the younger group, the older group showed significant differences as follows: smaller anterior chamber volume (160+/-39 vs. 247+/-39 microl; mean +/- SD; P< .00001), reduced aqueous flow (2.4+/-0.6 vs. 2.8+/-0.8 microl/minute; P = .002), and reduced uveoscleral outflow (1.10+/-0.81 vs. 1.52+/-0.81 microl/minute; P = .009).
  
  
  CONCLUSIONS
  In the healthy aging eye, there is a reduction in the production of aqueous humor and a reduction in its drainage through the uveoscleral outflow pathway.
authors.affiliation: Department of Ophthalmology, University of Nebraska Medical Center, Omaha 68198-5540, USA. ctoris@mail.unmc.edu
authors.forename: C B
authors.initials: CB
authors.lastname: Toris
authors.forename: M E
authors.initials: ME
authors.lastname: Yablonski
authors.forename: Y L
authors.initials: YL
authors.lastname: Wang
authors.forename: C B
authors.initials: CB
authors.lastname: Camras
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000867:Anterior Chamber / Q000502:physiology; D001082:Aqueous Humor / Q000378:metabolism*; D005260:Female; D015590:Fluorophotometry; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D012590:Sclera / Q000098:blood supply / Q000502:physiology; D014065:Tonometry, Ocular; D014602:Uvea / Q000502:physiology; D014690:Venous Pressure