We consider the response of choroidal melanoma to brachytherapy insufficient when tumor height regression is less than about 50% of the original thickness1 and when no change in internal reflectivity is noticed on ultrasound scan, when atrophic changes in and around the tumor are absent on ophthalmoscopic examination, and when leakage of fluorescein is still profuse on angiographic examination. In case of doubt, we perform transpupillary thermotherapy for 2 reasons: because the risk of complications from transpupillary thermotherapy is low; and because when tumors recur, they are associated with an at least 2-fold increase in metastatic disease. Ongoing tumor growth is not considered an insufficient response to treatment; it is considered no response at all.
Oosterhuis JA. Transpupillary Thermotherapy in 50 Patients With Choroidal Melanoma—Reply. Arch Ophthalmol. 1998;116(12):1697. doi: