Optic nerve infiltration in children with acute lymphoblastic leukemia (ALL) is a rare but critical neuro-ophthalmic emergency that signals central nervous system involvement or relapse. The study describes three cases of such patients. Patients received systemic chemotherapy, intrathecal chemotherapy, and in some cases orbital radiation therapy, resulting in varying degrees of visual recovery. The article reviews the literature on pathogenesis, clinical features, diagnostic approaches, imaging findings, and treatment strategies. It outlines a practical diagnostic and treatment framework with an emphasis on early recognition to reduce the risk of irreversible vision loss. In relapsed or refractory disease, intensified therapy including CD19 CAR T-cells and hematopoietic stem cell transplantation is considered. The condition requires prompt management between hematologists, oncologists, and ophthalmologists, with early treatment improving visual outcomes and survival.