ダイオードレーザーによる網膜芽細胞腫の光凝固

Diode laser photocoagulation in the management of retinoblastoma

　網膜芽細胞腫3例4眼11腫瘍に対しダィオードレーザー（波長800nm）による光凝固を行った。ダイオードレーザー光凝固装置を手術用顕微鏡に接続し，患児は全身麻酔下に仰臥位の姿勢とし，比較的大きなスポットサイズで低出力，長時間の条件で主として腫瘍本体の直接凝固を行った。11腫瘍中9腫瘍は1〜2回の光凝固で瘢痕化した。1腫瘍は7乳頭径と大きかったため放射線外照射と化学療法を併用し計4回の凝固を行った。1腫瘍は2乳頭径の大きさであったが再発し，再度光凝固を行った。ダイオードレーザーの波長は近赤外領域であるため組織深達性がよく，腫瘍の直接凝固に有効な手段であると思われた。

We treated 4 eyes in 3 cases of retinoblastoma by diode laser photocoagulation with the wavelength of 800 nm. The patients were males aged 4, 9 and 18 months. A total of 11 tumor masses were present in the 4 eyes. Seven of the tumors had previously undergone external beam radiotherapy. The diode laser was mounted on an operating microscope. Our technique involved treating the tumor surface with large-spot, long-exposure and low-energy photocoagulation. The rationale for this technique was that heating the whole tumor mass would produce thermal cell death with minimal risk of rupturing the internal limiting membrane and of spreading the tumor cells into the vitreous. Nine of 11 tumors were cured by 1 to 2 sessions of photocoagulation. Of the remaining two, one recur-red necessitating 3 additional treatments. The other needed supplemental treatment with external beam irradiation and chemotherapy. The present treat-ment with diode laser was thus effective, partly due to the deep penetration of laser energy into the tumor mass because of the longer wavelength.