Eye biometrics is a method of measuring the anatomical structures of the eye. Technological advances in ophthalmology allow for an increasingly accurate assessment of the biometric properties of the human eye. The biometric characteristics of the human eye differ in different populations and change over one’s lifetime as a result of normal physiological aging processes. It is crucial to know the exact biometric values for a particular population as they influence the prevention of various diseases, diagnosis, as well as further therapeutic strategies. This is the first study of biometric properties in healthy adults (Zagreb County) measured by optical instruments and includes correlations of measured biometric characteristics of the anterior and posterior segment of the eye with age, body height and body weight in this specific age group. No such or similar research has been conducted in the Republic of Croatia so far, nor are there biometric studies in healthy pre-biobiotic populations. Aim: The aim of this study was to measure the biometric characteristics of the anterior and posterior segment of the eye in emmetropic (healthy eyes) healthy prepresbyopic (middle-aged) subjects in Zagreb County using modern technologies. Participants and methods: Respondents in this study conducted at the Clinic for Ophthalmology of the Clinical Hospital "Sveti Duh" in Zagreb, were members of the young adult population (ages 18 to 39). The expected sample size was 200 subjects of both sexes, mostly students and persons who come for regular systematic ophthalmological examinations and whose visual acuity was corrected to 1.0. A detailed overview of the research methods used includes biometric measurements of the anterior and posterior segment of the eye, using two devices: optical biometer based on the principle of low coherence reflectometry – LS 900® from Haag Streit and spectral optical coherence tomography – OCT HS 100 from Canon, without prior use of any drug which could have had an impact on the biometric properties of the eye. Study design: Prospective scientific study. Results: Differences between the sexes were found by analysing the measured biometric characteristics of the anterior and posterior segment of the eye. There are associations of measured biometric characteristics of the anterior and posterior segment of the eye with general anthropometric characteristics (body height, mass, and age). Conclusion: Accurate assessment of biometric properties of the healthy adult pre-presiopian population of Zagreb County contributes to a better understanding of the differences between the observed sexes, physiological aging processes and correlations between general (body height and weight) and biometric properties of the eye. MeSH/keywords: biometry; lens; eye; anterior chamber; macula lutea; optic nerve; yellow