Nasal-Temporal Variations in Local Oxygen Saturation in Healthy Controls
Published 2022 by Kelly Bisignano
Co-Author(s): Jennyffer Smith, Wendy Harrison
Program Number: 225192
Article Type: Scientific Program
Local retinal oxygen saturation is a relatively new research technique which has potential as a biomarker for diseases such as diabetes. Understanding natural variations with this technique is important to quantify pathological differences as compared to controls in future studies. The purpose of this study is to examine and identify regional differences in oxygen saturation around the macula and how they relate to age and blood pressure.
50 healthy subjects aged 22-69 (mean 35± 13 years) were recruited for this study. Local retinal oxygen saturation was taken with the Zilia Oximeter (Quebec, Canada) in 4 locations around the macula 3.1 degrees from the fovea (superior temporal, superior nasal, inferior temporal and inferior nasal). Each quadrant was compared to the other individually, as well as combining regions to compare nasal, temporal, superior, and inferior. All subjects were confirmed to have no diabetes via normal HbA1c values. Blood pressure was also evaluated. Regression analyses were used to evaluate the relationship between oxygen saturation and other factors. T-tests were used with corrections for multiple comparisons to evaluate regions.
There were differences in oxygen saturation around the macula. The inferior nasal region (58.5%) exhibited the highest average oxygen saturation, with the lowest in the superior temporal region (51.0%) (p<0.002 corrected t-test). Additionally, differences observed inferior temporal (53.2%) and superior nasal (57.2%) indicated an overall nasal-temporal variation (p<0.0001). This was also confirmed through averaging these regions. In 81.3% of the subjects, we found the nasal results to have higher oxygen saturation than the temporal results. There was no relationship between oxygen saturation and age (p=0.22) nor oxygen saturation and blood pressure (p=0.82 systolic, p=0.56 diastolic).
Nasal-temporal variations were observed around the macula. However, we did not find blood pressure nor age-related changes in oxygen saturation. We hypothesize these divisional oxygen saturation variations are related to the trajectory of the blood vessels around the macula as there are larger and more dense vessels nasally. This is important to note for other studies that may want to use this new technology.