In dioptric media, due to the refraction of probe light in the sample and the mismatch of the optical distance with the actual distance, a major impediment to the use of optical coherence tomography (OCT) is its image distortions. This paper describes ray trace method of geometrical optics algorithm for numerical correction of the unavoidable image distortions in the raw image obtained by fiber based spectral domain OCT system, and theoretically deduces the mapping from the raw image of dioptric media to its actual structure. Experimentally, this method is adopted to correct the image of the glass tube and the anterior segment of human eye. The reconstructed image of the glass tube is coincident with the actual structure, and the measured physiological parameters of the human eye, such as cornea thickness, anterior chamber depth and width, pupil width, curvature radius of front and rear surface of cornea, and curvature radius of front surface of lens, are within the reference ranges given by the model one. The method enables OCT system to be applied to dioptric media containing multiple refraction interfaces, including the imaging of complicated optical system consisting of battery of lenses.