Retinal magnification factor at the ora terminals: a structural study of human and animal eyes.

A geometrical method of calculating retinal magnification factor at the limits of the retinal field, adjacent to the ora terminalis, is described. The method is applied to the eyes of 11 mammalian and avian species, using new anatomical measurements and data from the literature. In the human and monkey eye, magnification at the far periphery is substantially smaller than at the posterior pole; in cat, rabbit, rat and mouse there is lesser reduction; in pigeon, tawny owl and starling magnification is closely similar at the far periphery and posterior pole.