Abstract
Purpose :
Angiogenesis is an important parameter in growth and metastasis of choroidal melanoma. Vascular changes do not only occur inside tumours, but also affect the retina, as macular vascular changes were detected with modern OCTA technology in melanoma eyes. The mechanisms involved are not fully understood. Retinal oximetry (Oxymap T1) is a new technique to study retinal oxygen metabolism and vascular disease, and may help us to understand vascular changes in melanoma eyes. The aim of this study was to identify characteristics of retinal oxygenation in eyes with choroidal melanoma or nevi.
Methods :
The affected and fellow eye of patients with untreated choroidal melanoma (n=45) or choroidal nevus (n=42) were investigated using non-invasive retinal oximetry (Oxymap T1). Oxygen saturation of arterioles and venules was determined, together with the arteriovenous difference (AV-difference). The ‘Relative-AV-difference’ was calculated by extracting the AV-difference of the fellow eye from the lesion-containing eye.
Results :
The mean age of the choroidal melanoma patients was 65.5 years. Lesions were staged T1 (n=14, 31%), T2 (n=21, 47%), T3 (n=7, 16%) or T4 (n=3, 7%), and had a mean thickness of 4.0mm. The mean age of the choroidal nevus patients was 66.0 years. The mean nevus thickness was 1.8mm. In choroidal melanoma patients, the mean arterial saturation of the affected and fellow eye was 94.8% vs 93.2% (p=0.006), the mean venous saturation was 58.0% vs 60.0% (p=0.014) and the AV-difference was 36.8% vs 33.2% (p<0.001), respectively. In nevus patients, these numbers were 94.5% vs 94.2% (p=0.565), 60.5% vs 61.3% (p=0.350) and 34.0% vs 32.9% (p=0.182), respectively. The largest increase in AV-difference was observed between the retinal halves without the lesion in melanoma eyes compared to the corresponding retinal halve in the fellow eye (37.5% vs 32.1%, p<0.001). Older age was related to an increased Relative-AV-difference in melanoma eyes (p<0.001).
Conclusions :
Retinal oximetry is altered in eyes with untreated choroidal melanoma, but not in eyes with choroidal nevi. Eyes with choroidal melanoma show increased arterial saturation, decreased venous saturation and an increased AV-difference. Our results imply that choroidal melanoma is associated with vascular changes previously undescribed, possibly caused by a higher metabolism, with larger oxygen consumption and inflammation, leading to altered blood flow and oxygen relocation in the eye.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.