Treatment of retinoblastoma with indirect ophthalmoscope laser photocoagulation

The indirect ophthalmoscope laser photocoagulation delivery system is relatively new and is potentially applicable for treating selected small retinoblastomas. There has been very little reported on the results achieved with this laser delivery system in the treatment of retinoblastoma.

We reviewed all patients with retinoblastoma managed by indirect ophthalmoscope laser photocoagulation on the Ocular Oncology Service between July 1, 1991 and July 1, 1994. The individual tumor size, location, and proximity to the optic disc and foveola, as well as the laser power, duration, and number of sessions ,were recorded. We assessed the tumor response to treatment and the visual outcome of the patients.

There were 30 retinoblastomas in 20 eyes of 18 patients managed with indirect ophthalmoscope laser photocoagulation over the 3-year period. The mean tumor base was 2.1 mm (range: 1 mm to 8 mm); the mean tumor thickness, 1.2 mm (range: 0 mm to 3 mm). The tumor margin was a mean of 6.5 mm (range: 0 mm to 19 mm) from the foveola, and 7.7 mm (range: 0 mm to 22 mm) to the optic disc. In general, it required a power of approximately 350 mW and a continuous duration lasting 1 to 4 seconds to obtain satisfactory obliteration of feeding blood vessels. The tumor responded in one to three sessions (mean: 1.9 sessions per tumor). Complete regression occurred in 21 tumors (70%) and local recurrence in nine (30%). The recurrent tumors were successfully treated with plaque radiotherapy in seven cases and cryotherapy in two cases. The central vision was minimally distorted due to foveal traction from the laser treatment in three cases.

Indirect ophthalmoscope laser photocoagulation is an effective conservative method to manage selected small retinoblastomas. Tumors treated by this technique should be followed closely due to the moderate risk for local recurrence.