title: The effect of voluntary fasting and dehydration on flicker-induced retinal vascular dilation in a healthy individual: a case report.
abstract: BACKGROUND
  Dynamic retinal vessel analysis represents a well-established method for the assessment of vascular reactivity during both normal conditions and after various provocations. We present a case where the subject showed abnormal retinal vessel reactivity after fasting voluntarily for 20 hours.
  
  
  METHODS
  A healthy, 21-year-old man who fasted voluntarily for 20 hours exhibited abnormal retinal vascular reactivity (dilation and constriction) after flicker provocation as measured using the Dynamic Retinal Vessel Analyser (Imedos, Jena, Germany).
  
  
  CONCLUSIONS
  The abnormal vascular reactivity induced by fasting was significant; abnormal levels of important nutrients due to fasting and dehydration could play a role through altering the concentration of vasoactive substances such as nitric oxide. This hypothesis needs further investigation.
authors.affiliation: School of Life and Health Sciences, Aston University, Birmingham, UK. heitmarr@aston.ac.uk
authors.forename: Rebekka
authors.initials: R
authors.lastname: Heitmar
authors.forename: Doina
authors.initials: D
authors.lastname: Gherghel
authors.forename: Richard
authors.initials: R
authors.lastname: Armstrong
authors.forename: Robert
authors.initials: R
authors.lastname: Cubbidge
authors.forename: Sarah
authors.initials: S
authors.lastname: Hosking