title: Oscillatory potentials and the b-Wave: partial masking and interdependence in dark adaptation and diabetes in the rat.
abstract: BACKGROUND
  Diabetes inhibits dark adaptation and both processes alter the electroretinogram (ERG) in similar ways. This study aimed to investigate the relationship between oscillatory potentials (OPs) and the b-wave during dark adaptation and to determine if this relationship changes during the development of diabetes.
  
  
  METHODS
  Twenty-one rats were assigned to adaptation, control and diabetic groups. Rats were dark adapted for periods between 20 minutes and 4 hours, and ERGs recorded. Diabetes was induced with streptozotocin, and ERGs measured after 3, 6, 9 and 12 weeks after injection.
  
  
  RESULTS
  Increasing periods of dark adaptation led to a logarithmic increase in the amplitude of the b-wave and the OPs. This was accompanied by a decrease in the peak times of the OPs and b-wave. Total OP amplitude and b-wave amplitude were linearly related, allowing an empirical OP constant to be developed to describe the relationship between the two parameters. Diabetes led to a progressive decrease in the amplitude and increase in the peak time of all waves. The OP constant decreased in a linear fashion with increasing duration of diabetes.
  
  
  CONCLUSIONS
  It is argued that OP masking of the b-wave could explain previous inconsistencies in reported ERG changes in diabetes and that a slowing of dark adaptation does not account for these ERG changes. The report concludes that the OPs and b-wave amplitudes and latencies are intimately related in the normal retina and that this correlation is lost predictably during the development of diabetes.
authors.affiliation: Nuffield Laboratory of Ophthalmology, Oxford University, Walton St, Oxford OX2 6AW, UK. chris.layton@laytonvision.com.au
authors.forename: C J
authors.initials: CJ
authors.lastname: Layton
authors.forename: R
authors.initials: R
authors.lastname: Safa
authors.forename: N N
authors.initials: NN
authors.lastname: Osborne
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003623:Dark Adaptation / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D004596:Electroretinography; D008297:Male; D009991:Oscillometry; D010470:Perceptual Masking / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D001786:Blood Glucose