Broadly, my research is focused on better understanding how the damaged, adult visual system can repair itself. Is the system capable of such plasticity? What are the principles governing such processes?
Our first research avenue examines neuronal changes that underlie and behavioral properties that characterize recovery of visual functions after visual cortex damage in adulthood. Psychophysical techniques are used to both measure and retrain visual performance following damage to the visual cortex. In the past, neurochemical studies in an animal model allowed us to correlate neuronal changes with the degree and type of visual recovery attained as a function of training. For the last 10 years, we have applied this knowledge to humans with cortical blindness (in the form of hemianopsia or quadrantanopsia). In addition to behavioral characterization of the properties of the recovery that can be attained with different training paradigms, we are interested in using attentional and other manipulations (e.g. transcranial magnetic stimulation, pharmacology) to enhance the recovery potential of the damaged visual system. Functional MRI is then used to study how the remaining cortical circuitry is altered by both damage and subsequently, by training. It is hoped that this body of work will not only improve our understanding of the plasticity inherent in brain-damaged individuals with vision loss, but will also ultimately improve how we treat this underserved patient population in the clinic.
Our second research avenue studies the interplay between corneal wound healing and optical quality of the eye. The eye is the sensory input to the entire visual system and it relies on a transparent and properly-shaped cornea. If the cornea is damaged, this impairs all of vision. Our laboratory is unique in having developed a behaviorally fixating animal model in which we can reliably measure optical aberrations of the eye with the same degree of precision (and using the same instruments) as in humans. We can then study corneal damage and scarring - one of the major causes of blindness world-wide, and for which there is currently no effective treatment without side-effects. Using our unique animal mode, we can correlate optical aberrations, corneal structure and biology in health and disease. Such complex correlation is essential if we are to gain the knowledge necessary to design better ways of correcting optical aberrations, with minimal side-effects in terms of corneal and ocular health.
By applying the knowledge gained in this work, we are also contributing to the development of what we hope will be a safe, non-damaging form of laser refractive correction. This method is named femtosecond-IRIS or Blue-IRIS. Instead of ablating the cornea to change its shape, IRIS uses a femtosecond laser to alter its refractive index, thus altering the cornea's light-bending properties. This fully-customizable method appears to cause no corneal scarring and opens up both a new area of theoretical investigations into corneal biology related to laser-tissue interactions. It may also allow us to create a whole new paradigm for vision correction in humans.