Indocyanine Green (ICG) Enhanced Transpupillary Thermotherapy (TTT) for Hypopigmented Choroidal Melanoma

Abstract

Objective: Transpupillary thermotherapy (TTT) using an infrared diode laser at 810 nm is a new treatment modality for small choroidal melanoma, but less effective in hypopigmented tumors. We evaluate the effectiveness of intravenous ICG as an adjuvant to increase heat uptake in the tumor tissue and it's influence on tumor regression. Methods: In a prospective nonrandomized analysis 12 eyes suffering from primary choroidal melanoma (hypopigmented and posterior to the equator with thickness ≤4.5 mm) were treated with ICG augmented TTT (diode laser at 810 nm, beam diameter 2–3 mm, power setting 0.5–1.0 Watt, exposure time 6–26 minutes). The energy of the laser beam starting with 0.3 Watt at the tumor center was increased by 50 mW-steps for one minute till development of gray edema on the tumor surface indicates completion of the treatment spot, which were delivered in overlapping confluency, including 0.5 mm of clinically normal tissue around the tumor margin. 2 minutes after start of TTT 100mg indocyanine green in 10 cc aqueous solvent were injected intravenously over 20 seconds. 8 tumors previously showed insufficient regression after TTT without dye or ruthenium-106 plaque radiotherapy. 4 amelanotic melanoma had no previous treatment. Patients were followed up for at least 9 month. Results: 6 eyes revealed tumor regression to a completely flattened scar within 2–4 month after one treatment session. 3 eyes flattened after two sessions within 6–8 month. 3 eyes were judged as failures (two required ruthenium-106 radiotherapy because of insufficient regression after two sessions TTT and one eye was enucleated because of regrowth after radiotherapy and TTT). Visual acuity was unchanged or improved in 7 eyes. Ocular side effects were epiretinal gliosis (2), macula edema (1) and temporary retrobulbar pain (3). No metastases were seen during follow-up. Conclusions: Indocyanine green is an effective dye to increase heat uptake and efficiacy of transpupillary thermotherapy for primary hypopigmented choroidal melanoma as well as residual tumor prominences with secondary loss of pigmentation after brachytherapy or TTT. Longer follow-up is necessary for data regarding ultimate local tumor control and metastatic disease.