Cryotherapy was applied to 138 intraocular retinoblastoma tumors from 113 patients who were followed up for a mean of 40 months (four to 144 months). Overall, 70% of tumors were cured with cryotherapy and 93% of patients treated with cryotherapy survived. Twenty-one tumors were treated initially with cryotherapy alone, and 20 such tumors were cured. Twenty-seven new tumors appeared in eyes after radiation therapy and of these, 23 were cured with cryotherapy. Thirty-nine tumors were treated with cryotherapy after unsuccessful treatment with external beam irradiation, and 35 were cured with cryotherapy. Twenty-eight patients developed implantation seeds at the vitreous base after external beam irradiation but cryotherapy failed in each of these cases. There were few long-term ocular complications from cryotherapy despite intensive, heavy, and repeated cryotherapy. The limiting factor that determines success of cryotherapy is the size, elevation, and location of the tumor.
