3D reconstruction of endothelial surface of organ‐cultured corneas to improve their quality control

Abstract

Abstract Purpose Corneal endothelium of organ cultured cornea forms a 3D surface because of corneal curvature and of the Descemetic folds (of hundreds of μm depth) that appear during storage. Eye bank technicians have therefore a risk of endothelial cell density (ECD) overestimation when counting on an image projection. Our aim is to develop a 3D reconstruction from a Z stack of images in order to take account of the local slope and increase ECD reliability Methods Z stacks of 35 images were acquired with a motorized light microscope (BX41, Olympus) through a x10 objective. After routine eye bank preparation with saline, EC appeared with a clear cytoplasm and dark borders but could locally show a contrast reversal. In each section, the best‐focused pixels were determined using focus measurement algorithms. Depth map and texture image were then separately generated and the 3D reconstruction was obtained by projecting the texture image onto the depth map. A new algorithm, based on projections onto eigenbases, was developed and compared to 5 existing algorithms. Comparison was done using 1/ simulated images with additive noises to assess the reliability and noise robustness 2/ true endothelial image Results The new algorithm exhibited a more robust behaviour in presence of noise than the other algorithms. 3D endothelial reconstructions were also visually better, especially in case of local contrast reversal Conclusion Using a technology easily transposable into an eye bank, a reliable 3D reconstruction is possible from routine images that are often of average quality with poor contrast and high background noise. Our next step is to integrate the local slope information to correct local ECD