Leukaemic infiltration of the optic nerve head: a rare site of initial relapse

A 24-year-old male patient with acute lymphoblastic leukaemia (ALL), in complete remission, presented with the symptoms of gradual onset painless diminution of vision in the right eye (OD) of 2-month duration. On examination, best-corrected visual acuity in OD was finger-counting at 1 m and near vision was less than N₃₆ Anterior segment examination was normal, except for the presence of relative afferent pupillary defect in OD. Fundus examination showed optic disc oedema, peripapillary and vitreous haemorrhage, dilated and tortuous veins over the disc and presence of subretinal infiltrates and subretinal fluid around the optic disc. Clinical picture was suggestive of leukaemic infiltration of the optic nerve head. Cytological analysis of the cerebrospinal fluid did not show any abnormal cells or blasts .Vitreous biopsy from OD was suggestive of leukaemic infiltration. After radiotherapy, the leukaemic infiltrates regressed and visual acuity improved to 6/6, N₆ in OD.