Proptosis assessment using Hertel exophthalmometry is an essential part of the ophthalmic examination, but normal reference values vary among different populations. This observational study aims to establish normative Hertel exophthalmometry values in Mexican adults and to evaluate their association with demographic characteristics (such as age and sex) and systemic diseases. Healthy adult participants and adults with selected systemic conditions will undergo standardized Hertel exophthalmometry measurements. The findings are expected to provide population-specific reference values that may improve the clinical assessment of orbital diseases in the Mexican population.