Most of the sources studying retina seem to suggest that retinal connectome is hardwired and species dependent (like specialized vertical movement detector in small rodents). I couldn't find a single publication exploring possibility of learning within retina. My understanding of learning is somehow rewiring ganglion-amacrine neural circuits based on which visual features are useful for a particular individual.
Modern artificial neural networks use backpropagation to learn feature detectors but there seems to be no information flowing from brain back to retina. I guess that would mean that backpropagation isn't possible in biological visual system. That in itself doesn't rule out other mechanisms of learning.
Are there grounds to believe that retinal wiring is immutable or it is just lack of research on the topic?