Neuroleukemia is a severe complication of hemoblastosis, which manifests as lymphoblastic lesions of the brain and cranial nerves. Isolated damage to one of the cranial nerves is rare. The diagnosis is based on the results of ophthalmoscopy, magnetic resonance imaging of the orbits, and lumbar puncture. Literature describes isolated cases of retinal and/or optic nerve damage in the absence of blast cells in the spinal fluid. These are the most difficult situations for timely diagnosis of neuroleukemia. The article describes a patient with MALT lymphoma transformed into diffuse B-large cell lymphoma manifesting as leukemic infiltration of the optic nerve and retina without brain damage and absence of blast cytosis in the spinal fluid. The diagnosis of neuroleukemia was established based on the results of cytological examination of the punctate of the infiltrated peripapillary retina and confirmed by regression of changes in the fundus against the background of antitumor treatment. The vital prognosis for patients with neuroleukemia is unfavorable. However, early diagnosis of leukemic infiltration of the optic nerve and/or retina can restore visual acuity of the affected eye and significantly improve the quality of life.