Visual system emmetropia.

Based on the fundamental task of the visual system, which is to receive information from the surroundings and to transmit it to the central nervous system, the visual system is described as being emmetropic if the amount of information received through the visual pathways is maximum when the eyes are unaided. A mathematical model of the dependence of the amount of information received through the visual channels on the eye's refractive power and range of clear vision has been worked out. The model, by showing good correlation with common experience, confirms the hypothesis that the amount of information is a coefficient of an eye's approximation to emmetropia and that the criterion of emmetropia of an eye is a particular case of the criterion of emmetropia of the visual system.