放射線脈絡膜症における脈絡膜循環の再構築

Remodelling of choroidal blood flow in radiation choroidopathy

　走査レーザー検眼鏡による広角赤外螢光造影を用いて，放射線網膜症2例2眼について、放射線照射後の脈絡膜循環を広範囲に観察した。2例とも照射領域の脈絡膜には，脈絡毛細管板から脈絡膜中・大血管にかけて閉塞性変化があり，残存脈絡膜静脈は選択的に拡張していた。放射線による網膜血管障害が強い1例では，照射の影響が強い上耳側の渦静脈が消失し，この象限の静脈血液が黄斑耳側の分水嶺を越えて下耳側の渦静脈に流入する現象，脈絡膜動脈および静脈の乗り換え現象が観察された。放射線照射による閉塞性障害は，網膜血管だけではなく脈絡膜血管にも及ぶこと，照射の影響が網膜血管よりも脈絡膜血管で顕著に現れること，そして代償的に脈絡膜循環には多彩な変化が生じていることが証明された。

Two males, aged 68 and 34 years each, presented with radiation retinopathy. One had received radiation therapy to the whole brain for intracranial metastasis of lung carcinoma 29 months before. The other underwent surgery and radiation for melanoma of the upper eyelid 15 years before. When examined by indocyanine green angiography, both cases showed vasoocclusive changes in the choroid involving the choriocapillaris and major vessels in the affected fundus area. In one eye with severe retinal vascular lesions in the superior temporal quadrant, the vortex vein in the quadrant had obliterated. The venous blood in this quadrant was drained into the inferior temporal vortex vein crossing the presumed watershed zone temporal to the macula. Collaterals had formed between choroidal arteries and between choroidal veins. These cases illustrate that choroidal vascular lesions may be present in radiation retinopathy, that the former may be more pronounced than the latter and that choroidal vessels may undergo extensive remodelling to compensate for the disturbed choroidal circulation.