<h4>Aim</h4>Our study aimed to evaluate serum oxidative stress-related biomarkers (three pro-oxidants: total oxidant status (TOS), indirect assessment of nitric oxide synthesis (NOx), and malondialdehyde (MDA), and three anti-oxidants: total anti-oxidant capacity (TAC), catalase (CAT), and thiols) in patients with keratoconus (KCN).<h4>Methods</h4>We conducted a single-center, cross-sectional study with the prospective enrollment of adult patients attending an outpatient ophthalmology clinic between 1 January 2024, and 1 September 2025. This evidence concerns the gene CAT and keratoconus.