The human eye: From Gullstrand’s eye model to ray tracing today

In order to understand how the vision process works, than to develop and design precise optical systems and instruments, the optical modelling of the human eye and the accurate prediction of the optical performance is a crucial topic for the light engineering as well as vision science. In the past, various optical eye models with different features were developed, among them the Gullstrand’s schematic eye model won the Nobel prize in 1911 [1]. He illustrated relevant optical surfaces (the cornea and the crystalline lens) of an eye and described their geometry quantitatively. After 100 years, today, the development of optical simulation software and ray tracing methods enable us to reproduce the optical system of the human eye quantitatively with more accuracy. For instance, to construct a statistical eye model, at first the biometrical data of the human eye was assessed using clinical devices, than new simulated data were generated and finally validated with biometric data [2]. However, previous eye models focused particularly only in some features like only corneal data, only accommodation or aging, used personalised or average population data and either mono- and polychromatic light. To the best of our knowledge, there is no eye model of the complete optical system. Therefore, developing a complete eye model may prove advantageous to understand the vision process and its application in the ophthalmology, the medical technology and the light engineering. This paper presents a review of optical eye models and provide insight into which facts will play an important role to develop a complete eye model by using contemporary technology.