The mouse retinogeniculate synapse is a powerful developmental experimental model for studying the underlying mechanisms of synapse elimination and refinement over development. It was generally thought that retinogeniculate synaptic remodeling diminished after eye opening. However, studies from our laboratory have shown, on the contrary, robust synaptic plasticity that continues well into the young adult. After the initial refinement of the circuit, there is a critical period during which the connections between retinal ganglion cells and relay neurons can rewire in response to sensory experience. To understand the structural basis for this sensory-dependent synaptic remodeling, we took advantage of transgenic mice to label and reconstruct single axon arbors from a subset of retinal ganglion cells over different developmental time points. We find that RGC axon arbors remain larger than functionally necessary until adulthood. Instead, boutons increase in size and cluster to a few regions of the broad axon backbone during development. Surprisingly, retinal axons do eventually prune, but only after the completion of the thalamic critical period. Our findings indicate that in the CNS, alternative mechanisms, including dynamic bouton redistribution, AMPAR trafficking and homeostatic plasticity play prominent roles in circuit refinement. Importantly, they also suggest that neuronal circuits can continue to rewire into early adulthood.