In Reply In a letter published in this issue of JAMA Ophthalmology, Uner et al comment on the new horizon for genetic analyses of retinoblastoma tumors brought forth by our study1 on the possibility of biopsying aqueous humor for retinoblastoma. The study presented a proof of principle that the aqueous humor (AH) can serve as a liquid biopsy (in other words, as a surrogate to tumor biopsy) for retinoblastoma, which cannot otherwise be safely accessed in vivo. If tumor-derived DNA can be routinely extracted from the AH in patients who have retinoblastoma, it has potential to alter the way we manage this disease. We agree with Uner et al that, on any new horizon, one must proceed cautiously and with a clear vision.