The effect of voluntary fasting and dehydration on flicker-induced retinal vascular dilation in a healthy individual: a case report

Abstract

Introduction: 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.

Case presentation: 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).

Conclusion: 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.

Figure 1

(A) Initial measurement of retinal arteriole diameter under fasting and normal conditions (blue and red, respectively), (black lines showing normal range in healthy subjects). (B) Average curve of all four observations under fasting and normal conditions (blue and red, respectively).

Figure 2

(A) Initial measurement of retinal venule diameter under fasting and normal conditions (light blue and dark blue, respectively), (black lines showing upper and lower confidence limits in healthy subjects). (B) Average curve of all four observations under fasting and normal conditions (light blue and dark blue, respectively).

Figure 3

Retinal venule reaction time under normal conditions (TX-V-norm) and under fasting conditions (TX-V-fast).