Contextualization in mathematics is relevant due to the current aim that students can use what they learn in school to explain phenomena of reality. Therefore, the purpose of this research is to characterize the difficulties that arise when students from high school address a real-world problem in the field of visual perception. The method used corresponds to didactic engineering, which is done by confronting historical-epistemological research on Euclid's Optics and the students' answers when dealing with a problem that is designed on the basis of such study. The results revealed difficulties, both in the tendency that students show when justifying their answers about the studied phenomenon and the restrictions caused by the approach of the angle inscribed theorem.