A number of theoretical and experimental models analyze regulation of eye growth in humans and animals. In this article we introduce a biophysical theory to explain human eye growth from an energetic point of view. We find different energy densities of the electromagnetic radiation in the retina for hyperopic, emmetropic and myopic eyes. We postulate a relation between the different energy densities of the radiation in the retina and growth regulation by the retina. Based on this relation between physics and biology we are modeling emmetropization, missing emmetropization in severe hyperopia and development and progression of myopia in correspondence with a number of clinical and experimental results.