Clinical optometric findings on 332 inmates, adult male felons, of a state prison referred to the consulting optometrist for routine services were subjected to statistical evaluation and comparison with data available from nonprison samples. No significant differences between the prison sample and variously available outside adult male samples were apparent in the frequency distribution of attainable acuities, spherical and cylindrical refractive errors, cylindrical axis orientations, lateral and vertical phorias, and the bifocal additions at various age levels. This apparent lack of differences may reflect inadequacies of the comparisons to data not collected or presented in directly comparable manners.A significant frequency distribution difference was found in the interpupillary distances, with mean differences of 0.8 mm, 0.8 mm, and 2.1 mm less in each of three other adult male samples, respectively. No explanation is apparent. A number of statistical observations indicated that a relatively high proportion of inmates had not received or submitted to adequate optometric care prior to that obtained in the prison, that is, they had received significantly less care then comparably aged males who present themselves to public clinics and private practitioners for routine optometric services.