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We compiled data from the literature and colleagues to examine the relationship between eye axial length and body weight for vertebrates as well as birds, mammals, reptiles, and fishes independently. After fitting the data to logarithmic and semi-logarithmic models, we found that axial length of vertebrate eyes does obey a conventional logarithmic relationship with body weight rather than a semi-logarithmic relationship as suggested by the results of previous studies [Handbook of Sensory Physiology, VII/5: The Visual System in Vertebrates, Springer-Verlag, Berlin, 1977; The Allometry of the Vertebrate Eye, Dissertation, University of Chicago, UMI, Ann Arbor, T28274, 1982]. The regression slopes and intercepts appear to be characteristic of various animal groups. The axial length of the eye is largest in birds and primates, smaller in other mammals (especially rodents) and reptiles, and widely varying in fishes.