Low-cost eye phantom for stereophotogrammetry-based optic nerve head topographical 3D imaging

Glaucoma is the second leading cause of blindness globally. Stereophotogrammetry-based optic nerve head topographical imaging systems could potentially allow for objective glaucoma assessment in settings where technologies such as optical coherence tomography and the Heidelberg Retinal Tomograph are prohibitively expensive. In the development of such systems, eye phantoms are invaluable tools for both system calibration and performance evaluation. Eye phantoms developed for this purpose need to replicate the optical configuration of the eye, the related causes of measurement artefacts, and give the possibility to present to the imaging system the targets required for system calibration. The phantoms in the literature that show promise of meeting these requirements rely on custom lenses to be fabricated, making them very costly. Here, we propose a low-cost eye phantom comprising a vacuum formed cornea and commercially available stock bi-convex lens, that is optically similar to a gold-standard reference wide-angle schematic eye model and meets all the compliance and configurability requirements for use with stereo-photogrammetry-based ONH topographical imaging systems. Moreover, its modular design, being fabricated largely from 3D-printed components, lends itself to modification for other applications. The use of the phantom is successfully demonstrated in an ONH imager.