Analysis of errors in corneal topography evaluation caused by distortion aberration in the camera lens of a cone corneal topographer

We study the effects on corneal topography when the topographer camera is affected by distortion aberration, causing a nonuniform magnification in the image recorded by the camera sensor. As a result, images present a size change which could mislead the interpretation of the vertex position of the anterior corneal surface. Images numerically generated and distorted using the Seidel's aberrations are used to carry out the analysis. According to the results presented in this paper, while the reconstruction algorithm accurately recovers the central region of the surface, there are pronounced deviations between the retrieved surface and the actual surface towards the periphery. These deviations could lead to the underestimation or overestimation of the parameters associated with the base surface for a contact lens, affecting the correction of refractive errors such as myopia, hyperopia or astigmatism. Moreover, if the corneal topography provided by a topographer affected by distortion aberration is used for corneal reshaping via laser ablation, the refractive errors might be overcorrected or undercorrected. Thus, this paper highlights the importance of performing a proper calibration procedure for the distortion aberration of the corneal topographer camera, in order to reliably recover an accurate corneal topography.