[Unilateral loss of visual function with edema of the optic nerve in a 35-year-old male patient].

Ocular manifestations of acute lymphoblastic leukemia (ALL) are manifold. A funduscopic image which shows optic disc edema, serous retina detachment, intraretinal hemorrhages and infiltrations indicates an extramedullary recurrence of ALL. Reduction of visual acuity in patients in remission can often be one of the first signs of ALL relapse and can also occur without systemic changes. Regular ophthalmologic and oncologic controls are of great importance. The early recognition of ALL relapse is important to initiate early treatment. However, the prognosis for visual acuity is usually low.