A retinal reboot for amblyopia | MIT Technology Review

In the vision disorder amblyopia (or “lazy eye”), impaired vision in one eye early in life causes neural connections in the brain’s visual system to shift toward supporting the other eye, leaving the amblyopic eye less capable even if the original impairment is corrected. Current interventions don’t work after infancy and early childhood, when the brain connections are fully formed.  Now a study in mice by MIT neuroscientist Mark Bear and colleagues shows that if the retina of the amblyopic eye is anesthetized just for a couple of days, those crucial connections can be restored, even in adulthood. Bear’s team, which has been studying amblyopia for decades, had previously shown that this effect could be achieved by anesthetizing both eyes or the non-­amblyopic eye, analogous to having a child wear a patch over the healthy eye to strengthen the “lazy” one.  The new study delved into the mechanism behind this effect by pursuing an earlier observation: that blocking the retina from sending signals to neurons in the part of the brain that relays information from the eyes to the visual cortex caused those neurons to fire “bursts” of electrical pulses. Similar patterns of activity occur in the visual system before birth and guide early synaptic development. The experiments confirmed that the bursting is necessary for the treatment to work—and, crucially, that it occurs when either retina is targeted. After some mice modeling amblyopia had the affected eye anesthetized for two day...