Leptomeningeal carcinomatosis (LC) and optic nerve metastasis are uncommon occurrences in breast cancer. We report a rare case of LC with optic nerve infiltration secondary to breast cancer. A 45-year-old lady who was a known case of treated right breast carcinoma six years ago presented with a blurring of vision in both eyes, floaters, and diplopia for one month. She also had recurrent attacks of seizure-like episodes, headache, and vomiting. Examination revealed high blood pressure with tachycardia. Her right eye visual acuity was counting fingers at two feet and 6/36 in the left eye. She had right abducens nerve palsy. Fundoscopy showed bilateral optic disc swelling with pre-retinal, flame-shaped haemorrhages and macular oedema. CT scan of brain and orbit was normal. She was admitted for further investigations. While in the ward, her vision deteriorated further. Her visual acuity in both eyes was at the level of no perception to light. She also developed bilateral abducens nerve palsy and right facial nerve palsy. Subsequently, she started having bilateral hearing loss. There were few episodes of fluctuations in conscious awareness. MRI brain showed mild hydrocephalus. Both optic nerves were thickened and enhanced on T1-weighted and post-gadolinium. Lumbar puncture was performed. There was high opening pressure. Cerebrospinal fluid cytology showed the presence of malignant cells. Family members opted for palliative care in view of poor prognosis. Unfortunately, she succumbed after a month's stay in hospital. Diagnosis of LC and optic nerve infiltration presents a formidable challenge to clinicians especially in the early stages where neuroimaging appears normal and lumbar puncture has high false negatives. Multiple high-volume taps are advised if clinical suspicion of LC is high.