What indicator suggests a complete response to cryotherapy treatment for retinoblastoma?

A presence of a pigmented scar is an important indicator of a complete response to cryotherapy treatment for retinoblastoma. During treatment, cryotherapy aims to destroy tumor cells by freezing them, and the subsequent formation of a pigmented scar suggests that the tissue has healed properly following this localized treatment. It indicates that the tumor has been effectively treated, and the pigment results from the normal healing process of the retinal tissue.

Other outcomes, such as complete transparency of the anterior segment or preserved visual acuity, may not directly correlate with the efficacy of the cryotherapy in eliminating the tumor itself. The absence of any vascularity can indicate a lack of blood supply to the area but may not provide definitive evidence of tumor response. Hence, the presence of a pigmented scar is a clear and specific marker of a successful treatment response in this context.