Methods: Images of the retina of full-term healthy infants were obtained with an Optomap 200Tx (Optos, plc.), with laser wavelengths 532nm and 633nm. Imaging was performed using the modified “flying baby position” (described by Patel et al. 2013). The images were analyzed using the modified Oxymap Analyzer software. This software algorithm allows calculation of Optical Density Ratio (ODR) and relative oxygen saturation levels of the retinal vessels. The ODR is inversely related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis.
Results: Fifty-nine infants, 25 males (42%)/34 females (58%), were included with mean gestational age 40 weeks and mean post natal age 16 days. The ODR was 0.277 ± 0.062 (n = 33, mean ±SD) for the arterioles and 0.429 ± 0.094 for the venules. The diameter of retinal vessels was 15 ± 3 pixels (arterioles) and 20 ± 4 pixels (venules). A paired t-test showed a statistically significant difference in ODR between the arterioles and venules (n = 33, p < 0.0001).
Conclusions: Retinal oximetry can be performed on full-term infants using an SLO and dual-wavelength algorithm without the use of invasive means like mydriatics and eye speculum. However the variability of the saturation measurements of the retinal vessels remains an issue, which needs to be resolved.