Abstract: The paper presents the complex structure of the human tear film. From the optics point of view the homogeneously distributed tear film on the corneal surface makes this diffused surface optically smooth. Every eye blink distributes a new portion of tears on the surface of the cornea or the contact lens. If the production of tears is not sufficient or their composition is inappropriate, the tear film is deteriorated and so called tear film break-up (TFBU) appears on the surface of the cornea. These local break-ups of the smooth tear film introduce disturbances in the phase of a quasiplane wavefront falling on the cornea from a far-located point source of light. Two types of the TFBUs are considered in this paper. Topography of a point one and a linear one form of the break ups are approximated by use of four different continuous functions. The modeled topography of the TFBU is used for calculation of the local variation of the wavefront phase. The Point Spread Function of the eye model is calculated by use of the Fast Fourier Transform without and with the different approximations of TFBUs. It is shown that different type of TFBU approximation influences significantly the form of the Point Spread Function of the eye.!7
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