Amblyopia therapy –” it’s no longer just for kids.” These are the words used by Dr. Michael DePaolis in a recent editorial in Primary Care Optometry News. He describes a big moment in optometry, a paradigm shift in patient care. New research has made it very clear that neuroplasticity in the adult brain is alive and well, and the implications reach far beyond the treatment of amblyopia. But let’s start with amblyopia.
Dr. Dennis Levi explored the use of action video games to treat adults with amblyopia. Why would playing action video games be an effective treatment of amblyopia? “Action game play is extremely varied in its demands and rich in the set of visual experiences it offers. Thus…. the very act of action game playing seems to train the brain to learn, on the fly, how to make the best use of the available information in the display, independent of the specifics of this display, allowing for the broad transfer of learning.” Levi had 20 amblyopic adults play action video games with only their amblyopic eye. All 20 subjects improved. Levi speculates that video game playing is “arousing and rewarding.” Neurotransmitters such as acetylcholine and dopamine are released, and these neurotransmitters are associated with enhanced neuroplasticity. Compliance is also enhanced, because action video games are more interesting and fun to play than many traditional vision therapy activities.
Now consider some incredible research by Dr. Elizabeth Quinlan. Dr. Quinlan’s presentation at COVD’s annual meeting focused on the treatment of amblyopia, specifically on possible mechanisms to enhance neuroplasticity. She has been recording the electrical response of the part of the brain associated with vision (aka the visual cortex) resulting from different types of visual stimulation. In one series of experiments, she created amblyopic animals (in this case, amblyopic rats) by occluding one eye for an extended period of time. The resulting pattern of visually evoked potentials from portions of the visual cortex was significantly altered in a pattern that reflected the lack of visual input from the occluded eye. When the occlusion was ended and the animals had a chance to receive normal visual experience, this pattern of altered electrical activity in the brains of the rats did not improve. In other words, there was no neurophysiological recovery when normal visual experience was restored. That is, there was no neurophysiological recovery until she put these animals in the dark. After placing these animals in total darkness for 3-10 days, and then providing a short period of “rat vision therapy,” these rats had a complete neurophysiological recovery. The visual evoked responses from the visual cortex demonstrated a more balanced input from each eye. The dark exposure enhanced the neuroplasticity of the visual cortex which is the basis for successful treatment of amblyopia.
Are we ready for another paradigm shift in the treatment of amblyopia? Of course, this research was done with rats and involved recording electrical activity from electrodes placed into their visual cortex. That is a very long way from clinical trials that might provide evidence of more effective treatment of amblyopia by enhancing neuroplasticity in the human brain after dark exposure. But I cannot help but wonder …… can we provide a safe environment of total darkness for adult patients to enhance their neuroplasticity and then provide vision therapy programs that utilize action video games? who will open the first Hotel Amblyopia?