Purpose: To determine the extent of expansion of laser scars after single treatment with transpupillary thermotherapy (TTT) for retinoblastoma.
Design: We retrospectively reviewed medical records and RetCam (Massie Industries, Dublin, CA) digital fundus photographs of patients with retinoblastoma who received TTT by use of an 810-nm diode laser with large-spot indirect ophthalmoscope. Digital images were measured by use of RetCam software beginning immediately after treatment. Lesions were measured in both linear size and area by 2 observers. In addition, optic disc diameters were also measured for each image.
Participants: We identified 9 patients with hereditary retinoblastoma who were treated from 1997 to 2000.
Main outcome measures: Linear and area expansion of laser scars as a function of time.
Results: Fourteen tumors in 10 eyes were treated successfully with 1 session of TTT. Follow-up for all eyes was at least 16 months. Scars of 12 of the 14 lesions increased beyond their original borders (mean starting linear diameter, 2.02 mm; range 1.46-2.59 mm; mean increase, 0.72 mm [36%]) over time, most within 6 months to 1 year after treatment.
Conclusions: Scars from TTT for retinoblastoma may increase in size after treatment. This expansion must be considered when applying TTT to tumors near vital macular structures, such as the fovea and optic nerve.