title: Gas stress test for assessment of corneal endothelial function.
abstract: OBJECTIVE
  This study was undertaken to evaluate the endothelial pump function by monitoring both corneal swelling response under hypoxia and dehydration response following hypoxia in vivo.
  
  
  METHODS
  Humidified nitrogen gas was used to obtain corneal swelling, and humidified gas mixed with oxygen and nitrogen was used for corneal dehydration. First, in 6 young volunteers, we investigated the most suitable oxygen level for evaluating pump function by changing oxygen levels. Then, with the optimal oxygen level, we attempted to evaluate pump function in 53 normal subjects, 5 Fuchs' dystrophy patients, and 3 iridocorneal endothelial syndrome (ICE) patients.
  
  
  RESULTS
  Swelling rate showed similar values regardless of age, but both dehydration rate and swelling rate plus dehydration rate decreased with aging. The swelling rate of 5 guttata corneas was significantly higher than that of age-matched control corneas. In contrast, dehydration rate markedly decreased in guttata corneas, while the swelling rate plus dehydration rate of guttata corneas was comparable to that of age-matched corneas. In the 3 ICE corneas, however, swelling rate, dehydration rate, and swelling rate plus dehydration rate were markedly lower than those of both the fellow corneas and the age-matched control corneas.
  
  
  CONCLUSIONS
  These observations lead us to conclude that in order to evaluate pump function, it is necessary to monitor not only dehydration response following hypoxia but also swelling response under hypoxia.
authors.affiliation: Department of Ophthalmology, Osaka University Medical School, Osaka, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ohguro
authors.forename: M
authors.initials: M
authors.lastname: Matsuda
authors.forename: M
authors.initials: M
authors.lastname: Fukuda
authors.forename: S
authors.initials: S
authors.lastname: Kinoshita
authors.forename: Y
authors.initials: Y
authors.lastname: Tano
mesh_terms: D000328:Adult; D000368:Aged; D001693:Biological Transport, Active; D003316:Corneal Diseases / Q000378:metabolism*; D015715:Corneal Edema / Q000378:metabolism; D003681:Dehydration / Q000378:metabolism; D004728:Endothelium, Corneal / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D014463:Ultrasonography
chemical_list: D009584:Nitrogen; D010100:Oxygen