Direct Laser Writing of Titanium Dioxide-Laden Retinal Cone Phantoms

• Main Authors: Lamont, Andrew C., Restaino, Michael A., Alsharhan, Abdullah T., Liu, Zhuolin, Hammer, Daniel X., Agrawal, Anant, Sochol, Ryan D.
• Format: Conference Proceeding
• Language: English
• Subjects: 3D printing; Adaptive Optics-Optical Coherence Tomography; Computer architecture; Direct Laser Writing; Imaging phantoms; Nanoparticles; Phantoms; Retina; Retinal Phantom; Three-dimensional displays; Titanium Dioxide; Writing
• ISSN: 2160-1968
• DOI: 10.1109/MEMS46641.2020.9056425

Adaptive optics-optical coherence tomography (AO-OCT) is a developing medical imaging modality that can spatially resolve individual photoreceptor cell and detect retinal pathologies in vivo. To date, however, a lack of standardized physical models - termed "phantoms" - that recapitulate the opto-structural properties of the retina impedes performance assessment, which could lead to inconsistencies in retinal pathology detection once AO-OCT reaches the clinic. Here we present a novel approach for manufacturing three-dimensional (3D) retinal cone outer segment (OS) phantoms via two-photon direct laser writing (DLW) of a photomaterial laden with titanium (IV) dioxide (TiO 2 ) nanoparticles. The ability to directly integrate light-scattering particles into biologically relevant architectures facilitates AO-OCT visibility of phantom components. Preliminary DLW results demonstrated TiO 2 nanoparticle-laden phantoms that effectively match cone dimensions and spacing at 1°, 2.5°, 5°, and 10° retinal eccentricities. Furthermore, preliminary AO-OCT experiments revealed that individual retinal cones could be optically resolved in phantoms with center-to-center spacing less than 4\ \mu \mathrm{m} . These results suggest a promising pathway to produce biologically relevant retinal phantoms to standardize clinical AO-OCT imaging performance.