Evaluation of the Geometry of the Anterior Segment of Postmortem Human Eyes with two Imaging Systems

Purpose: High-frequency ultrasound and anterior segment optical coherence tomography (OCT) systems can be used to obtain non-invasive measurements of the anterior segment. The purpose of this study was to evaluate the geometry of the anterior segment of the human eye using these systems. Materials and Methods: Human eyes obtained postmortem were fixated to special eye holders and underwent anterior segment scanning using a 50MHz ultrasound system with digital enhancement (Artemis, Ultralink; 20 eyes), and an anterior segment OCT (SL-OCT, Heidelberg Engineering; 24 eyes). Four meridians were evaluated in each eye (vertical, horizontal, 135 and 45 degrees). Angle-to-angle dimensions were measured in the different meridians using the ultrasound and the OCT systems. Sulcus-to-sulcus dimensions were also measured in the different meridians using the ultrasound.

Results: In the ultrasound study, the differences between the measurements of angle-to-angle and sulcus-to-sulcus dimensions performed in the four above-mentioned meridians of 20 eyes analyzed were found to be statistically significant (P=0.002 and P=0.009, respectively). In the OCT study, the differences between the measurements of angle-to-angle dimensions performed in the same four meridians of 24 eyes analyzed were also found to be statistically significant (P=0.005). Conclusion: This study suggests that internal geometry of the anterior segment of human eyes is not round. This has significant relevance for the correct sizing of phakic intraocular lenses, as accurate sizing has the potential to reduce postoperative complications associated with them.