  With a kind of magnetism, the human retina draws the eye of neuroscientist
and physicist alike. It is attractive as a self-organizing system, which forms
as a part of the central nervous system via biochemical and mechanical cues.
The retina is also intriguing as an electro-optical device, converting photons
into voltages to perform on-the-fly filtering before the signals are sent to
our brain. Here, we consider how the advent of stem cell derived in vitro
analogs of the retina, termed retina organoids, opens up an exploration of the
interplay between optics, electrics, and mechanics in a complex neuronal
network, all in a Petri dish. This review presents state-of-the-art retina
organoid protocols by emphasizing links to the biochemical and mechanical
signals of in vivo retinogenesis. Electrophysiological recording of active
signal processing becomes possible as retina organoids generate light sensitive
and synaptically connected photoreceptors. Experimental biophysical tools
provide data to steer the development of mathematical models operating at
different levels of coarse-graining. In concert, they provide a means to study
how mechanical factors guide retina self-assembly. In turn, this understanding
informs the engineering of mechanical signals required to tailor the growth of
neuronal network morphology. Tackling the complex developmental and
computational processes in the retina requires an interdisciplinary endeavor
combining experiment and theory, physics, and biology. The reward is enticing:
in the next few years, retina organoids could offer a glimpse inside the
machinery of simultaneous cellular self-assembly and signal processing, all in
an in vitro setting.
