Schematic and reduced eyes for the horse, cow, sheep, pig, cat, and dog were calculated from optical parameter values obtained from the literature. Calculations were performed with the aid of a computer program using standard Gaussian equations and a homogeneous lens model. Calculated schematic eyes had refractive states within 1.5 D of emmetropia; retinal image sizes ranged from 0.22 (cat and dog) to 0.44 (horse) mm/deg. The cat eye presented here is more nearly emmetropic than a previously published cat schematic eye. The effects of altering refractive indices, radii of curvature, and thicknesses of refractive components upon refractive state and retinal image size are examined. The largest differences resulted from changes made to refractive indices of the lens and vitreous and to the vitreous depth.