Purpose:We describe the use of chick chorioallantoic membrane (CAM) as a model system for the study of the precision and safety of vitreoretinal microsurgical instruments and techniques.Methods: The CAM was prepared for experimentation with and without its inner shell membrane (ISM) attached for in vivo and in vitro experiments that simulated medical and surgical interventions on the retina.Results: The CAM's ease of use, low cost, and anatomic structure make it a convenient model for surgical retinal and retinal vascular modeling.Conclusion: While CAM has been used extensively in the past for ocular angiogenesis studies, we describe the tissue as a useful tool for a variety of other applications, including (1) testing of novel surgical tools and techniques for cutting and coagulating retina and its vasculature, (2) testing vessel cannulation and injection techniques, (3) angiographic studies, and (4) endoscopic surgery.

The Artificial Synapse Chip is an evolving design for a flexible retinal interface that aims to improve visual resolution of an electronic retinal prosthesis by addressing cells individually and mimicking the physiological stimulation achieved in synaptic transmission. We describe three novel approaches employed in the development of the Artificial Synapse Chip: (i) micropatterned substrates to direct retinal cell neurite growth to individual stimulation sites; (ii) a prototype retinal interface based on localized neurotransmitter delivery; and (iii) the use of soft materials to fabricate these devices. By patterning the growth of cells to individual stimulation sites, we can improve the selectivity of stimulation and decrease the associated power requirements. Moreover, we have microfabricated a neurotransmitter delivery system based on a 5- micro m aperture in a 500-nm-thick silicon nitride membrane overlying a microfluidic channel. This device can release neurotransmitter volumes as small as 2 pL, demonstrating the possibility of chemical-based prostheses. Finally, we have fabricated and implanted an equivalent device using soft flexible materials that conform to the retinal tissue more effectively. As many of the current retinal prosthesis devices use hard materials and electrical excitation at a lower resolution, our approach may provide more physiologic retinal stimulation.