Focal therapy in the management of retinoblastoma: When to start and when to stop

Purpose: To describe the treatment effects and side effects of different mo dalities of focal treatment used for retinoblastoma. Methods: Green(532-nm) laser, continuous wave Nd:YAG(1064-nm) laser, transpupillary or transclera l (810-nm) laser, and cryotherapy were used in the treatment of 46 eyes in 35 patients affected with retinoblastoma. The number of treatment sessions and the amount of energy applied were recorded in an attempt to determine t he amount of energy required to adequately treat tumors of various sizes. I n addition, we have attempted to determine when treatment becomes overtreat ment and is likely to lead to complications. Results: The treatment endpoin t for laser in this study was calcific, gliotic, or flat scars. Small tumor s (<2 mm in height, <4 DD) were successfully treated in 3 or fewer sessions of 532-nm laser. Anterior small tumors were successfully treated with tran scleral 810-nm laser or cryotherapy. Medium tumors,between 2.0 and 4.0 mm i n thickness, required 2 to 9 treatments to achieve a good response end ofte n required the addition of chemotherapy to reduce the size of the tumor bef ore or during laser treatment. Large tumors required chemotherapy combined with many laser treatments for complete control. Complications associated w ith excessive laser were vitreo us condensation with traction, vitreous hem orrhage, retinal detachment, tumor break, cataract formation, and iris burn s. Conclusion: Laser treatment alone for small tumors, and combined with cr yotherapy and chemotherapy for larger tumors, is effective in the treatment of retinoblastoma. Complications of focal therapy can most often be avoide d by using the minimal effective laser power.