Optic pathway cavernous malformations represent less than 1% of all central nervous system cavernomas. They can lead to visual loss with indeterminate speed, and therefore, the timing of intervention is controversial. We present a patient with an optic nerve cavernoma, which was discovered incidentally 3 years before the onset of visual symptoms. The evolution of her symptoms, visual function and radiographic findings are reported in detail. The cavernoma was eventually removed via a transciliary orbitocranial keyhole approach with the goal to protect the optic chiasm from progressive involvement. The function in the affected optic nerve was not salvageable. This is the second reported case of a cavernoma selectively involving the intracranial portion of the optic nerve. The debate on the timing of intervention is highlighted with reference to the natural history of these rare lesions.