Amblyopia, also known as ’lazy eye‘, is the leading cause of childhood visual impairment in the developed world and affects about one in 30 people. The most common types of amblyopia cause poor vision in one eye and stop the two eyes working together effectively. Amblyopia also doubles the lifetime risk of serious visual impairment which can occur if the good eye suffers damage or disease.
Counter-intuitively, lazy eye is not due to a problem with the eye itself, but is caused by abnormal brain development. If there is a mismatch between the images seen by each eye during early childhood, the visual areas of the brain may develop to process information from one eye abnormally. The mismatch may be the result of eye misalignment, unequal focus between the eyes or other impediments to vision such as a cataract. Irrespective of the cause, it is the disrupted brain development that leads to poor vision in the affected eye. This means that treating amblyopia involves changing the way in which the brain interprets information from the eyes.
The most common treatment for amblyopia is to cover the good eye with an eye-patch to encourage use of the amblyopic eye. Patching can be very effective when used in childhood but, many children find it difficult to wear the eye-patch and the treatment can last for many months or even years. Furthermore, patching is considered to be ineffective in older children and adults with amblyopia. This is because the mature brain is thought to lack the ’plasticity‘ or capacity for change, that is needed to learn how to use the amblyopic eye effectively.
With support from the AMRF, Associate Professor Ben Thompson and his colleagues have pioneered the development of novel approaches to the treatment of amblyopia in both adults and children. One of these new treatments takes a completely different approach to patching. Instead of forcing the use of the amblyopic eye, the new treatment encourages the two eyes to work together. This treatment can be given in the form of specially modified video games that can only be played if the two eyes cooperate. Initial studies have revealed highly promising results in both adults and children using this approach with improvements occurring in a matter of weeks.
A version of the treatment that runs on an iPod touch device is the focus of an international clinical trial led by Ben and supported by the Health Research Council. If the trial is positive, this technique could revolutionize the treatment of amblyopia.
Other promising approaches for adult patients include the application of safe, non-invasive brain stimulation techniques to the visual cortex and the combination of patching with Fluoxetine (Prozac), which has previously been found to reverse amblyopia in adult animals. Importantly, this research not only aims to improve vision, but is also designed to provide new insights into the mechanisms that control plasticity in the human brain. This means that studying the visual system could lead to the development of new treatment techniques that could be applied to a range of different brain disorders.
I studied experimental psychology at the University of Sussex in the UK and developed a particular interest in the areas of the brain that support vision. I then took up a position as a research fellow at the University of California, Los Angeles, USA, where I studied the changes that occur in the brain when people with normal vision learn new visual skills. My next research position within the Department of Ophthalmology at McGill University in Canada provided me with the opportunity to apply what I had learnt about the brain to the development of new treatments for brain-based visual disorders such as amblyopia. When I arrived at the Department of Optometry and Vision Science at the University of Auckland in 2008, I established new research programs in the area of amblyopia treatment and human brain plasticity and have also maintained strong ties with my international colleagues.
AMRF funding has played a central role in the development of my research. The first funding I received after joining the University of Auckland as a junior faculty member was an AMRF project grant. This grant allowed me to buy the equipment that I needed to establish my new laboratory and allowed me to hire an excellent full-time research assistant who helped me to drive the research forward. The success of these initial amblyopia treatment studies subsequently allowed me to secure funding from the Health Research Council and the Marsden Fund to grow the laboratory and further develop this area of research. The research funding environment in New Zealand is among the most competitive in the world and the funding I received from the AMRF early in my career allowed me to develop a research program that could deliver clinically relevant results and compete for government research funds.
Travel grants-in-aid from the AMRF have also allowed me to attend international conferences and present my work to international colleagues at their home institutions. I really can’t emphasise enough the importance of international networks in establishing a successful research program, particularly when the research has the long-term aim of contributing to international clinical practice. Conference attendance and presentations at international institutions allowed me to promote my research to an international audience and the networks I became a part of, allowed me to access international funding streams and build broad, productive collaborations. Attendance at international scientific conferences may be seen simply as a perk for researchers, but it is absolutely essential if New Zealand research is to make an impact on the international stage. Without travel support from the AMRF, establishing the networks required to launch projects such as the international clinical trial that I am currently leading, would not be possible. The clinical trial is called BRAVO (Binocular Treatment of Amblyopia using Video games) and includes study sites in Australia, Canada and Hong Kong. The video game based treatment for amblyopia being trialed was developed in close collaboration with colleagues in Canada.
Finally, doctoral scholarships from the AMRF have fostered new interdisciplinary research opportunities within the University of Auckland. I currently host two outstanding doctoral students in my laboratory who are AMRF scholarship recipients. Their research into visual development and plasticity brings together leading scientists and clinicians from the fields of ophthalmology, neonatology, pediatrics, neuropsychology and engineering.
Our video game approach to treating amblyopia that is being assessed in the BRAVO trial may provide an alternative to patching for children and pave the way for adults with amblyopia to be treated. This is important as current data suggest that amblyopia affects over 155,000 people in New Zealand alone. Our initial smaller-scale studies have found that the video game based treatment not only improves vision in the amblyopic eye, but can also restore 3D depth perception which requires both eyes to work together. In some cases, this was the first time that the patients had ever experienced 3D vision. In the longer term, current research into techniques that allow the adult brain to learn how to use an amblyopic eye may be applicable to a range of other neurological disorders that require skills to be relearned. I work closely with colleagues within the Centre for Brain Research at the University of Auckland to advance this goal.
Research is becoming increasingly globalised and research in the area of visual neuroscience is no exception. Collaborations within my laboratory include colleagues from over 20 different universities across 10 different countries including Canada, China, the USA and the UK. Work from my laboratory combined with work led by my international collaborators has started to change the way that we think about amblyopia and has generated a large number of international research programs investigating treatments designed to promote cooperation between the two eyes.
We are currently investigating the combination of multiple treatment approaches to see whether even greater vision improvements can be achieved in adults with amblyopia. I am also very interested in understanding the brain mechanisms that allow for vision to be improved and I am using a variety of brain imaging techniques to address this question. In addition, I am working closely with collages within the Department of Optometry and Vision Science, the Auckland Bioengineering Institute and the Liggins Institute on the development of new techniques for assessing vision in children that may allow for the early detection of vision and neurodevelopmental problems.
Patching has been the standard treatment for children with amblyopia for over 500 years and adults are currently left untreated. The development of new treatments that are effective for all ages and that involve fun activities such as playing video games would change the way we think about amblyopia and brain plasticity in general.