Abstract
Purpose: :
To measure and compare retinal oxygen saturation (O2Sat) in eyes treated using plaque radiotherapy with that of the fellow eye.
Methods: :
Eight patients with choroidal melanoma in one eye treated with plaque radiotherapy were included in the study. O2Sat was determined using the Oxymap (Reykjavik, Iceland) in both the treated eye and the fellow untreated eye. Arteriole and venule O2Sat from the superotemporal, superonasal, inferotemporal, and inferonasal quadrants of the treated eyes were compared to the corresponding quadrants of the fellow eyes. In addition, O2Sat of the irradiated retinal hemispheres were also compared to the opposite hemispheres of the same eye. Comparative analysis was performed using paired t-test.
Results: :
Mean age at the time of O2Sat measurement was 61 years (Range 40-82) and there were five females. Three patients were hypertensive, none were diabetic, and one had glaucoma. Mean interval from plaque application to measurement of O2Sat was 40 months (Range 2-88). All but one patient had radiation-related complications following plaque radiotherapy, and four had received intravitreal Bevacizumab prior to O2Sat measurement. The mean arteriole O2Sat in treated and fellow eyes was 91.3±9.2% and 90.3±11.6%, while mean venule O2Sat was 67.1±11.2% and 65.9±5.4% respectively. The differences in arteriole (p = 0.19) and venule (p = 0.61) O2Sat between treated and fellow eyes were not significant. Mean arteriole O2Sat in the irradiated and opposite hemisphere was 97.0±6.5% and 95.6±5.9%, while mean venule O2Sat was 68.2±6.8% and 66.2±8.3% respectively. There was also no significant difference in arteriole (p = 0.45) and venule (p = 0.28) O2Sat between the irradiated and opposite hemisphere of the treated eyes.
Conclusions: :
Although there appears to be a trend towards an increase of retinal oxygenation in arterioles and venules of eyes receiving plaque radiotherapy compared to their fellow eyes, as well as within the irradiated compared to the opposite hemisphere of the treated eye, this difference did not reach statistical significance.
Keywords: oxygen • retina • radiation therapy