Ogasawara K - Utilizing second-generation swept-source anterior segment optical coherence tomography (AS-OCT), the authors estimated marginal reflex distance-1 (MRD-1) values in normal individuals and patients with blepharoptosis and assessed the usefulness of this measurement method. MRD-1 values were measured utilizing AS-OCT in 80 eyes of 40 normal individuals (aged 20– 59 years) with no neurological or endocrinological disorders, and the measured values were compared between four age groups involving 20 eyes of 10 individuals each in their 20s, 30s, 40s, and 50s. According to findings, MRD-1 measurement using AS-OCT is a simple and reproducible method which allows the direct comparison of numerical values in both normal individuals and blepharoptosis patients.