Human Corneal Topographic Modeling And Evaluation Method

Eye model is an optical system which is applied to theoretical research of the refraction system of the human eye and simulates imaging of the eye. Schematic eye and cornea model are important research objects in visual optics and ophthalmology field. For researching influence of cornea topography on the image quality of the human eye and setting new evaluation method about cornea topography from the point of view of a imaging, based on analyzing the eye model of Isabel and Liou, current parameters of the human eye which is mentioned in many references are chosen. On the basis of the character of oriental eye and record in some Chinese references, the parameters are modified. The eye model and cornea model are upbuilt by Zemax, and the followings are described in details in six aspects in this paper:(1) The aspherical surface of cornea reduces the spherical aberration of the eye to about ± 0.20DS, which brings forward new cutting model for laser operations.(2) Gradient refractive index of the lens can decrease the value of wavefront aberration.(3) The surface describing with Zernike polynomials which is applied to anterior cornea may improve the image quality on the visual axis(5° visual field in Zemax model) and raise the value of Point spread function (PSF).(4) The aspherical surface or Zernike type of surface of cornea can be chosen as reference before the LASIK operations and for evaluating vision after operations. The opinion that the clinical diagnoses and image quality should be combined is brought forward in new evaluation method about cornea topography.(5)The eye model is beneficial to select the diopter of lens for cataract extraction by implanting an intraocular lens. The theoretics formula of the diopter of lens is given by mathematical means.(6)The hyperacuity eye model is upbuildt by analyzing the visual resolving power of the human eye and the wavefront aberration of the eye model.