Personalized geometrical models of the human eye developed from MRI scans at 9.4 Tesla

Abstract

Purpose : We develop data based geometrical models for individual human eyes where each organ is described by suitable mathematical functions. The model parameters are calibrated to high resolution 2D multi slice MRI scans of human autopsy eyes. The resulting geometrical models can be used as 3D printouts for experimental work in the laboratory or for grid constructions to perform numerical simulation of therapeutic approaches for several eye diseases like retinal diseases and glaucoma

Methods : We measured 7 autopsy eyes (Ethics votum S-134/2018) in a preclinical small animal MRI scanner (Bruker Biospec 94/20, Germany) using a Bruker quadrature volumetric transceiver coil. All procedures conformed to HIPAA regulations and the Declaration of Helsinki for research involving human subjects. Human autopsy eyes were enucleated within 24h after death and used within 48h. Intraocular pressure was adjusted to normal by injection of ophthalmic viscosurgical device (HEALON, Johnson & Johnson Vision, USA) near the optic nerve before examination. For measurements eyes were put into 50 ml centrifugation tubes (Sarstedt, Germany). Measurements were performed using a 2D RARE sequence with the following parameters: TE/TR=60/3085ms, FA=90°, Rare Factor 8, Resolution=100x100µm², Slices=24 with 4mm thickness, Averages=12, TA=22m49s

Results : From the generated digital imaging data (Fig. 1) we segment the geometry of the components of the eye (Fig. 2), i.e. anterior chamber, vitreous body, lens, iris, ciliary body, cornea and sclera. The mathematical models for the shape of these components are calibrated to these imaging data using parameter estimation methods (method of least squares) and are visualized in a 3D scene

Conclusions : With the MRI scans at 9.4 Tesla we obtained high resolution images to segment the components of the eye. With this data we reconstruct personalized human eye models which can be used for numerical simulation to test in silico personalized therapies of retinal diseases and glaucoma

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.

 

Fig. 1: left: the high resolution MRI scans at 9.4 Tesla of a human autopsy eye; middle: the 2D RARE sequence no 7 from totally 12, representing data of a slice of 4 mm thickness; right: the structures are captured with all details, here the lens, ciliary body, iris and cornea

 

Fig. 2: Geometrical representation of the single components of the human eye after segmentation and model calibration from the 3D MRI scans at 9.4 Tesla