June 26, 2015
The human brain is a fascinating organ
I just returned from a trip to Hong Kong to visit my mother. It was a quick turnaround; left on Thursday and back on Tuesday. I am still reeling from jet lag, which is why I am writing this blog at 3:00 AM waiting for the melatonin to kick in.
Mother has advanced Alzheimer and Parkinson, an unfortunate combo which rendered her to bed except for her doctor visits. Physically, she has recovered well from her stomach cancer surgery a year ago and now relies exclusively on tube feeding. She has a bed sore that is slowly healing, thanks to improved nutrition. Mentally, however, she appears to be slipping further and further away. I showed her pictures of the twins and I think she recognized them as her grandchildren. She would grin from cheek to cheek in one minute and stare into blank space in another. Her eyes were open but her mind was locked up inside a deep recess within her cranium. Among the millions of neurons that are tangled into a ball of yarn by her disease, a few pathways remain intact but dormant, waiting to be activated under the right conditions. I stumbled upon such as occasion when I was up at 1:00 AM, being jet lagged in that time zone. Her eyes were open and bright and she tracked me as soon as I stepped into her room. I asked her if she knew who I was and she answered unequivocally, yes. We talked about her father, a Western-trained doctor who was sent to a labor camp during the Cultural Revolution. We talked about her mother, her seven siblings and her arduous journey from China to Hong Kong. As I tried to help her to retrieve her distant memory, mom’s speech became more slurred but rapid. She then launched into a monologue as if to give me one last life lesson with all her remaining power of articulation. Tears streamed down my face as one more lesson from mother to son went unheard. Mom stopped speaking and looked visibly upset. She reached out to me with her tremulous hand and at that instance; I knew my mom was still there somewhere.
The human brain is a fascinating organ. Conventional wisdom believes that the human brain, once it reaches its natural maturity, has limited ability to regenerate if it is struck by diseases such as Alzheimer, stroke or trauma. But conventional wisdom is just that, conventional; and just plain wrong sometimes. New research findings from multiple disciplines suggest that the brain has the potential to heal and regain function more than previously thought. In my field, amblyopia, or commonly known as lazy eye, is a prime example. Amblyopia is the reduction of visual acuity caused by abnormal interaction between the two eyes during the critical period of visual development. There is usually a good eye and a bad eye. The bad eye produces a less clear image because of refractive errors (near-sightedness, far-sightedness or astigmatism), strabismus (misalignment of the eyes) or cloudy media (congenital cataract, for example). It is thought that the two eyes compete for neural connections in the occipital cortex (the back part of the brain) and this game is usually over by nine years of age when that part of the brain becomes relatively mature. When the two eyes are in equal footing, the connections to the brain are pretty balanced and they work together to afford us binocular vision and depth perception. When there is a good and a bad eye, the connections to the bad eye was thought to be under developed or even withered away in severe cases. Recent research, however, showed that at least for most forms of amblyopia, the pathways from the bad eye to the brain are actually intact, they are just dormant. The good eye is not cooperating with the bad eye but in fact working against it by suppressing its signals from coming through.
For centuries, the mainstay of treatment for amblyopia is to patch the good eye or blur the good eye with a dilating eye drop called atropine. The rationale is straight forward, we penalize the good eye so that the weak eye can re-establish connections with the brain. While these treatment modalities are generally effective, depending on the age of the patients, 15-50% of children failed to obtain normal acuity even after extended period of treatment. Furthermore, about a quarter of children lose acuity in the amblyopic eye once the treatment is stopped. This give us pause as to whether our conventional thinking is entirely correct. The traditional paradigm is punitive – hold back the good eye to prop up the bad eye. A new approach is to encourage the two eyes to cooperate with each other in order to restore binocular vision which we are naturally endowed with. I found this idea to be very exciting and I am proud that we are a center that participates in a trial supported by the National Eye Institute and administered through the Pediatric Eye Diseases Investigator Group.
In this trial, called Amblyopia Treatment Study #18, we compare patching the good eye two hours per day to playing one hour per day of a Tetris-like or falling block games on an iPad. The subject wears red/green glasses with the green filter over amblyopic eye. Some boxes are only visible to the good eye through the red lens, other boxes are only visible to the amblyopic eye through the green lens. Image contrast begins at 20% in the fellow eye and 100% in the amblyopic eye. Every day, the software adjust the contrast level based on an algorithm of performance and duration of play from the previous day in order to promote the weak eye while maintain cooperation between the two eyes.
Children who are five to less than seventeen years old with amblyopic eye vision 20/40 to 20/200 are eligible to participate in the study. Those who qualified will be randomly assigned to either patching 2 hours per day or to playing the iPad game an hour a day by the study center. We have no control over the assignment but those children who are randomly chosen to the patching group will be offered the opportunity to try the iPad treatment for sixteen weeks. Patches will be provided free of charge as will the iPad and the red/green glasses, which need to be returned at the end of the study. Visual acuity will be assessed at 4, 8, 12 and 16 weeks. Parents will be reimbursed for travel and other visit-related expenses throughout the duration of the study.
Please tell your friends and family about our study. The success (or lack thereof) of any sound medical treatment, be it for Alzheimer or Amblyopia, is dependent on subject participation. We all benefit from the current acceptable forms of treatment because someone else with the same condition participated in some study some time ago. When we take time to become a subject in a study, we are paying it forward – to help those who are in the same boat that follows us. It is an exercise of kindness, the most important lesson that I learned from mom.