title: Characterization of the pupil light reflex, electroretinogram and tonometric parameters in healthy rat eyes.
abstract: OBJECTIVE
  To characterize the pupil light reflex (PLR), electroretinographic (ERG) and tonometric parameters in healthy rat eyes.
  
  
  METHODS
  Brown Norway rats were used for experiments. The PLR was evaluated with a computerized pupillometer (n = 27), ERGs were recorded simultaneously from both eyes (n = 27) and IOP was measured with a Tonopen (n = 15).
  
  
  RESULTS
  The analysis of the PLR parameters confirmed that the consensual PLR had a significantly smaller amplitude (0.1-0.2 mm; p = 0.03) and an increased latency time (p = 0.001) compared to the direct PLR. Electroretinography revealed an a-wave amplitude of 207.2 +/- 13 microV with a latency of 25.6 +/- 0.7 ms, and a b-wave 554.3 +/- 24.5 microV with a latency of 21.4 + 1.8 ms. The flicker ERG recording revealed amplitudes of 40.6 +/- 2.4 microV. Tonometry measurements revealed that isoflurane, but not halothane, anesthesia suppressed the IOP (non-anesthetized: 25.3 +/- 1.0 mmHg; 1% halothane + 30% NO: 26.2 +/- 1.1 (p > 0.1); 1% isoflurane + 30% NO: 20.1 + 1.6 (p < 0.05)).
  
  
  CONCLUSIONS
  Consensual PLR in rats has a relative deficit compared to the direct PLR. Isoflurane anesthesia has a suppressive effect on the IOP in healthy rat eyes.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA. sgrozdan@iastate.edu
authors.forename: Sinisa
authors.initials: S
authors.lastname: Grozdanic
authors.forename: Donald S
authors.initials: DS
authors.lastname: Sakaguchi
authors.forename: Young H
authors.initials: YH
authors.lastname: Kwon
authors.forename: Randy H
authors.initials: RH
authors.lastname: Kardon
authors.forename: Ioana M
authors.initials: IM
authors.lastname: Sonea
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D004596:Electroretinography; D006221:Halothane / Q000008:administration & dosage; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D007530:Isoflurane / Q000008:administration & dosage; D008027:Light; D023421:Models, Animal; D051381:Rats; D011914:Rats, Inbred BN; D012025:Reflex, Pupillary / Q000502:physiology*; D012160:Retina / Q000502:physiology*; D014065:Tonometry, Ocular
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane; D006221:Halothane