Visiting Investigators

Dr. Jeffrey Marchant, Ph.D., Tufts University, Professor, Department of Anatomy and Cellular Biology

Dr. Marchant is a Research Assistant Professor at Tufts University School of Medicine and has been studying the vertebrate eye since graduate school. Much of the early work focused on the cornea and currently he is funded to develop a cornea replacement using silk scaffolds that have been seeded with human corneal cells. His research expanded to begin a characterization of the corneoscleral angle in the chicken and to study trabecular meshwork cells using human cell cultures. In 2005, Dr. Marchant began collaborating with Dr. John to further these studies by switching to mouse models of IOP regulation. The research has led to the discovery of a novel basement membrane specialization that appears to support Schlemm’s canal giant vacuoles throughout their expansion cycle. This specialization may also serve as a dynamic modulator of aqueous outflow resistance. Through the collaboration with Dr. John,  

Dr. Marchant has obtained external funding from the American Health Assistance Foundation - National Glaucoma Research. Dr. Marchant continues to spend time in Dr. John’s laboratory as a Visiting Investigator each summer. At Tufts, he can be reached at jeffrey.marchant@tufts.edu.

Dr. James Morgan, Ph.D., Cardiff University, Professor, School of Optometry & Vision Sciences

Dr. Morgan's research is aimed at understanding the structural and cellular changes occurring at the level of the optic nerve in glaucoma using clinical and laboratory based techniques. Glaucoma is one of the most common causes of vision loss in the UK population, affecting up to 2% of the population as a whole. Classically, it is associated with increased intraocular pressure, which causes the death of retinal ganglion cells and results in a slow and, if untreated, progressive loss of vision. In most cases, peripheral vision is lost first and is usually asymptomatic. By the time a patient notices restriction of visual field, advanced damage may have occurred to the optic nerve that is usually irreversible. Treatment is aimed at the reduction of eye pressure (intraocular pressure) to prevent this vision loss. Usually, this is achieved using eye drops although, in some cases, surgery or even laser treatment may be required. One of the key problems is in identifying the disease in its earliest stages and in detecting the first signs of retinal (optic nerve) damage. As a consultant ophthalmologist, Morgan runs a glaucoma service at the University Hospital of Wales. He currently chairs the Expert Working Group for the development of shared care glaucoma in Wales where they are working to develop the role of virtual clinics for the community care of patients with diagnosed glaucoma.  His email address is MorganJE3@cardiff.ac.uk. Clinical studies

These are based at the Retinal Imaging Laboratory and are directed at the quantification of structural optic nerve changes in the early stages of glaucoma. Since these precede the development of visual field changes as detected using clinical perimetric techniques, their detection should enable early disease diagnosis and improve the long-term prognosis for the patient. Morgan's lab is currently assessing the value of digital stereoviewing in the quantification of these nerve head changes. In addition, his lab is assessing the value of other imaging modalities such as OCT in the determination of optic nerve head changes that occur in early glaucoma.

Using a variety of in vivo and in vitro models of glaucoma, Morgan's group is investigating the mechanisms of retinal ganglion cell death in glaucoma. There is good evidence that these cells undergo a prolonged period of atrophy and remodeling prior to cell death, which is manifest as shrinkage and pruning in the cell body and dendritic processes. These changes will reduce the efficiency with which these cells can detect visual signals but also suggests that this damage could be reversed. They use techniques such as biolistics transfection to see if the overexpression of genes that might be beneficial for retinal neurons can result in cell rescue Retinal ganglion cell transfected with plasmid coding for GFP. Retinal Explant preparation after 24 hours in culture.

Pedro P. Irazoqui, Ph.D., Purdue University, Associate Head of Biomedical Engineering, Showalter Faculty Scholar, Associate Professor of Electrical and Computer Engineering, Director, Center for Implantable Devices

Dr. Irazoqui received his B.Sc. and M.Sc. degrees in Electrical Engineering from the University of New Hampshire, Durham in 1997 and 1999 respectively, and the Ph.D. in Neuroengineering from the University of California at Los Angeles in 2003.Currently he is an associate professor in the Weldon School of Biomedical Engineering at Purdue University, and director of the Center for Implantable Devices pursuing research into a modular approach to the design of biological implants. Devices are applied to the clinical treatment of physiological disorders, using miniature, wireless, implantable systems. Specific research and clinical applications explored include: epilepsy, glaucoma, cardiology, and neural interfaces.He has received the Best Teacher Award from the Weldon School of Biomedical Engineering (2006 & 2009), the Early Career Award from the Wallace H. Coulter Foundation (2007 & Phase II in 2009), the Marion B. Scott Excellence in Teaching Award from Tau Beta Pi (2008), and the Outstanding Faculty Member Award from the Weldon School of Biomedical Engineering (2009), and has been serving as Associate Editor of IEEE Transactions on Biomedical Engineering since late 2006.

Research Interests

• Application, design and fabrication of implantable analog integrated circuits

• High speed RF circuits for wireless data and power coupling to and from biological implants

• Real-time discrete-time signal processing for biological signals

• Neuronal substrates of behavior, perception and locomotion