Familial adenomatous polyposis (FAP) is a hereditary condition characterized by the early onset of hundreds to thousands of adenomatous colorectal polyps, with a high risk of colorectal cancer if untreated. While genetic testing and gastrointestinal symptoms often prompt diagnosis, certain extraintestinal manifestations, such as congenital hypertrophy of the retinal pigment epithelium (CHRPE), may offer early diagnostic clues. This case describes a female adolescent whose initial complaint was decreased visual acuity. This prompted an examination that revealed bilateral pigmented retinal lesions consistent with CHRPE, which subsequently led to the suspicion of FAP, despite the absence of gastrointestinal complaints or known familial mutations. Subsequent genetic testing confirmed a pathogenic variant in the APC gene, and colonoscopy revealed extensive polyposis. This case highlights the importance of recognizing ophthalmological manifestations as potential early indicators of inherited colorectal cancer syndromes. It also underscores the relevance of a multidisciplinary approach in managing complex hereditary diseases, with respect for patient autonomy and shared decision-making.