Diagnosis of Glaucoma by 3D Reconstruction of Optic Nerve Head with a Portable Ocular Imaging System

The field of optic nerve head (ONH) imaging is continuously evolving. Its main focus is to achieve higher quality in vivo images to resemble those achieved in histology. However, the use of expensive, sophisticated imaging devices is required, posing restrictions for populations that need it most. The main goal of this study is to obtain a proof-of-concept for a potentially low-cost 3D imaging system. The contribution to the field is a potentially low-cost, connected, portable, widely available 3D imaging platform, which can be used to assist in the early detection of glaucoma in underserved populations. Methods: The quadrascopic imaging platform (QuIP) for 3D imaging of the ONH has been conceptualized, optically modeled, synthesized, modeled mechanically, developed and calibrated for accuracy. A model eye was developed with 3D features similar to those of an ONH for the purpose of quantitatively evaluating the 3D reconstruction algorithms. Reconstruction algorithms perform a pixel-wise correspondence matching utilizing the epipolar geometries of the QuIP. Utilizing the four imaging planes the algorithm performs a cost analysis making a decision of which cameras best to use for triangulation of the observed retinal point. A standard bilateral eye exam was performed at the University of Illinois Eye and Ear Infirmary on a single 42 y.o. male subject with a Heidelberg Engineering Spectralis HRT+OCT. Image sets were subsequently captured using the QuIP. The ONH 3D structure was synthesized for both OS and OD eyes and cross section analysis compared to that of HRT OCT scans. Results: The synthesized 3D voxel cloud of the model eye was compared to the CAD model of the design. The mean residual error is calculated as 0.17 mm, and the correlation between the two the synthesized depths is r=0.85. The synthesized 3D structure voxel cloud of the OD and OS eyes is compared to the radial HRT OCT scan of the same eye. A star pattern radial cross section of the OD and OS ONH is compared to the synthesized structures. The mean residual error is calculated as 0.32 mm for the OS ONH and 0.24mm for the OD ONH. The correlation coefficient between depth values obtained from the synthesized 3D reconstruction compared to the HRT OCT radial scan is r=0.83 for the OS eye and r=0.78 OD.