[Influence of two different cameras on the spectrometric measurement of oxygen saturation]

Oxygen saturation in retinal vessels can be measured by spectrometry. However, there are no studies on the influence of different camera chips on these measurements. The presented study reports the effect of two different camera chips ("1-CCD" vs. "3-CCD") on the spectrometric measurements in the same patients.

61 eyes of 61 patients were included in this study. The study was approved by the local ethics commission. Patients were separated in 3 groups: the first group contained healthy volunteers, the second group patients with diabetes mellitus but without previous laser treatment, the third group included patients with diabetes mellitus and previous laser coagulation treatment. The oxygen saturation was calculated from the difference between wavelengths on and right next to the retinal vessel. This methodology uses the different absorption spectra of oxy- and deoxyhaemoglobin.

All 3 groups demonstrated valid outcomes of the retinal oxygen saturation in arterial and venous vessels. No significant differences we found in the arterial-venous oxygen difference between the two different camera chips (group 1 p = 0.063, group 2 p = 0.204, group 3 p = 0.059).

As no significant differences could be found between the two camera chips, the less expensive system should be used if the spectrometric measurement of oxygen saturation is added to an analysis system already established on the market.