The effect of rebreathing and hyperventilation on retinal and choroidal vessels measured by spectral domain optical coherence tomography

AbstractObjective: The purpose of this study was to examine the vasoreactivity in retina and choroid of the healthy eyes in response to experimentally altered partial arterial pressure of carbon dioxide (PaCO2) using a non-invasive technique, spectral domain optical coherence tomography (SD-OCT).Materials and methods: The study included non-smoking participants between 18 and 35 years of age, having visual acuity of 20/20 and with no systemic and ocular diseases. At baseline, the participants breathed room air (normocapnia). Hypocapnia was created with the help of hyperventilation; for this, the participants were instructed to draw deep and quick breaths, resulting one breathing cycle per 2 s. To create hypercapnia subjects rebreathed from a 5 l bag at least 3 min. Choroidal thickness and retinal artery diameter were measured at baseline, and hyperventilation and rebreathing conditions by SD-OCT.Results: Twenty eyes of 20 healthy subjects were included in this study. Their mean age was 24.90 ± 5.32 years....