SimEye: Computer-based simulation of visual perception under various eye defects using Zernike polynomials

Wolfgang Fink, Daniel Micol

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We describe a computer eye model that allows for aspheric surfaces and a three-dimensional computer-based ray-tracing technique to simulate optical properties of the human eye and visual perception under various eye defects. Eye surfaces, such as the cornea, eye lens, and retina, are modeled or approximated by a set of Zernike polynomials that are fitted to input data for the respective surfaces. A ray-tracing procedure propagates light rays using Snell's law of refraction from an input object (e.g., digital image) through the eye under investigation (i.e., eye with defects to be modeled) to form a retinal image that is upside down and left-right inverted. To obtain a firstorder realistic visual perception without having to model or simulate the retina and the visual cortex, this retinal image is then backpropagated through an emmetropic eye (e.g., Gullstrand exact schematic eye model with no additional eye defects) to an output screen of the same dimensions and at the same distance from the eye as the input object. Visual perception under instances of emmetropia, regular astigmatism, irregular astigmatism, and (central symmetric) keratoconus is simulated and depicted. In addition to still images, the computer ray-tracing tool presented here (simEye) permits the production of animated movies. These developments may have scientific and educational value. This tool may facilitate the education and training of both the public, for example, patients before undergoing eye surgery, and those in the medical field, such as students and professionals. Moreover, simEye may be used as a scientific research tool to investigate optical lens systems in general and the visual perception under a variety of eye conditions and surgical procedures such as cataract surgery and laser assisted in situ keratomileusis (LASIK) in particular.

Original languageEnglish (US)
Article number054011
JournalJournal of biomedical optics
Issue number5
StatePublished - Sep 2006


  • Asphericity
  • Astigmatism
  • Eye defects
  • Gullstrand's exact schematic eye model
  • Irregular astigmatism
  • Keratoconus
  • Ray-tracing
  • Simulation
  • Surface modeling
  • Visual perception
  • Zernike polynomials

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Biomedical Engineering


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