What happened, in summary

A 49-year-old man with rectal adenocarcinoma had metastatic disease in the lungs and liver. The tumor was BRAF mutant and KRAS wild type, and he had already received 18 cycles of chemotherapy.

He was referred after 3 months of progressive vision loss in his left eye. By the time of assessment, he could no longer perceive light in that eye. Examination showed swelling of the left optic nerve with small flame-shaped hemorrhages, while the front of the eye and eye pressure were normal.

Orbital imaging and his known metastatic cancer strongly suggested tumor involvement. Histology confirmed rectal adenocarcinoma compressing and invading the optic nerve. The optic-nerve metastasis added to an already high burden of disease involving the lungs and liver. His condition carried a poor prognosis, and he died about 4 months after the visual symptoms brought him to specialist care.