A 49-year-old man who competes in triathlons and reports never smoking suddenly loses vision in one eye, prompting medical evaluation. He is diagnosed with stage 4 lung cancer, despite having no history of tobacco use and no reported family history of the disease. The accounts describe the vision change as the initial symptom that leads to further testing and ultimately the cancer diagnosis. After the diagnosis, his treatment and medical follow-up begin in line with a stage 4 cancer assessment. The reports emphasize that the case involves lung cancer occurring in a person who does not fit the typical risk profile associated with smoking, highlighting that lung cancer can be diagnosed at advanced stages even in people who do not smoke. While the articles focus on the unusual presentation and the late-stage finding, they do not provide consistent additional details beyond the key facts: age, triathlete status, sudden loss of vision in one eye, and the subsequent identification of stage 4 lung cancer.