Visualization of porcine eye anatomy by X-ray microtomography.

The aim of our study is to obtain, as accurately as possible, porcine ocular tissue visualization using microtomography (micro-CT) method. We propose image contrast enhancement by different staining procedures with combination of micro-CT scanning. Porcine eye globes were investigated with Bruker-SkyScan 1172 micro-CT. We used 4F1G and Bouin's as sample fixation solutions and tincture of iodine, 100% Lugol, phosphotungstic acid and 1% osmium tetroxide solutions for staining. Quantitative and qualitative analysis was performed based on micro-CT reconstruction images histograms and 3D volume rendering models of investigated samples. This investigation showed that staining methods improved micro-CT image quality in case of ocular anatomy visualization. Characteristic profiles of the grey level distributions and quality of the cross-section and 3D volume rendering images confirmed the staining effect. Most significant contrast enhancement was obtained after 96 h staining in osmium tetroxide and Lugol solutions. The images of eye anatomical structures were characterized: cornea, lens, iris, ciliary body, vitreous, retina, choroid and sclera, vasculature and optic nerve. Staining of porcine eye globes used in this work leads to quality improvement of the micro-CT imaging. The most contrast images were obtained for Lugol and osmium tetroxide solutions. Different affinity of staining solutions to eye anatomical structures has been observed in the obtained images. Osmium tetroxide provides sharper image of conjunctiva, sclera, choroid, retina, iris and ciliary body structure. Lugol staining leads to more accurate vessels, cornea and optic nerve imagining.