The reasoning: an inverted, graded network
Layers (outer → inner): RPE, photoreceptor outer segments, outer nuclear layer, outer plexiform (photoreceptor–bipolar–horizontal synapses), inner nuclear layer (bipolar, horizontal, amacrine, Müller cell bodies), inner plexiform, ganglion cell layer, nerve fibre layer. Only ganglion cells (and some amacrines) fire action potentials routinely.