Ronald H. Silverman

Biography

Dr. Silverman has been involved in ultrasound research in ophthalmology for 30 years. His research includes development of high-resolution imaging systems, studies of safety/bioeffects, use of high-intensity ultrasound for therapy, perfusion imaging, and tissue characterization by use of signal-processing. He has applied these techniques for study of ocular disease in animal models and clinically. Dr. Silverman is Principal Investigator on an NIH-sponsored project utilizing high-frequency ultrasound for early diagnosis of keratoconus. The project, which is being performed in collaboration with Dan Reinstein, Director of the London Vision Clinic, involves mapping of early epithelial-thickness changes associated with changes in curvature of the underlying stroma. The study also includes characterization of the elastic properties of the cornea by use of acoustic radiation force impulse imaging (ARFI). He is also Principal Investigator a project using ARFI and vibro-acoustic imaging, another technique involving ultrasound radiation force, to study elastic properties of the retina and choroid in conjunction with phase-resolved optical coherence tomography (OCT). This project is being performed in collaboration with the University of Southern California (Qifa Zhou, Ph.D.) and the University of California at Irvine (Zhongping Chen, Ph.D.). With his collaborator, Raksha Urs, Ph.D., Dr. Silverman is working on means to allow delivery of riboflavin across the barrier of the corneal epithelium to allow stromal cross-linking with intact epithelium. At present, the epithelium is mechanically debrided to allow riboflavin to enter the stoma. They are exploring the use of low intensity ultrasound in the presence of gas-filled microbubbles to permeabilize the epithelium, allowing treatment without the pain and other issues arising from epithelial debridement. He is collaborating with Y.C. Chen, Ph.D. at Hunter College and Parag Chitnis, Ph.D. and Ashwin Sampathkumar, Ph.D. at Riverside Research and on photoacoustic imaging of ocular tissues. In this technique, ultrasound is emitted by tissues in response to absorption of light emitted by a laser. The technique images light absorption by pigments such as melanin and blood, and hence is quite different from conventional ultrasound. By varying the color of the laser source, an absorption spectrum can be produced that allows identification of specific molecules within the imaged tissue. The work with Riverside is focused on development of an all-optical means for photoacoustic imaging, which would be ideal for imaging the retina. He is working with Jeffrey Ketterling, Ph.D., Research Manager at the Frederic L. Lizzi Center for Biomedical Engineering at the Riverside Research Institute on the development of novel annular array transducers and pulse modes for imaging the eye with improved sensitivity and resolution. They have developed an annular array system that allows high-resolution imaging of the entire eye, which cannot now be accomplished either ultrasonically or optically. Their current activity centers upon development of a compact, hand-held probe that will facilitate clinical application. He has mentored and trained numerous students, fellows, and residents that have worked in his laboratory over the years and consider this an important aspect of his work. Dr. Silverman has numerous patents and was a co-founder of Ultralink, LLC, which, under license from Cornell University, developed the Artemis ultrasound system for imaging and biometric analysis of the cornea and anterior segment. Ultralink has since been acquired by Arcscan, Inc., which is further developing the technology. Dr. Silverman is active in several professional organizations. He served on the ARVO Program Committee, Anatomy & Pathology Section, from 2008-2011 and is currently on the program committee of the International Society for Imaging the Eye. He is also on the program committee and a co-organizer of the International Conference on Ultrasonic Biomedical Microscanning. He is a Fellow of the American Institute of Ultrasound in Medicine, a Fellow of the American Institute of Medical and Biological Engineers and a Senior Member of the IEEE. He is a member of the Advisory Board of the NIH Transducer Resource Facility at the University of Southern California. Aside from presenting and moderating at numerous meetings, Dr. Silverman has also often acted as an organizer for special sections. He is frequently asked to review articles in journals specializing in ophthalmology, ultrasound and optics. In addition, he serves as a grant-reviewer for the NIH. Since 2012, Dr. Silverman has been Director of the Basic Science Course in Ophthalmology (BSCO) which has been offered by Columbia University for over 40 years. The BSCO attracts students, primarily ophthalmology residents, from all over the world. The course consists of approximately 120 hours of lectures on clinical ophthalmology and vision research plus 20 hours of workshops and wet-labs, with lecturers from Columbia University as well as national and international luminaries in their fields. Staff Harriet O. Lloyd, MS, Senior Staff Associate Raksha Urs, PhD, Associate Research Scientist 

Research Interest

Imaging and characterization of ocular tissues with ultrasound alone or in combination with optics The use of high-resolution ultrasound to map the layers of the cornea to detect changes indicative of early keratoconus The use of ultrasound to remotely palpate tissues such as the cornea or retina to non-invasively probe their elastic properties, using both ultrasound and optical coherence tomography to measure ultrasound-induced tissue displacements The use of lasers in combination with ultrasound in a process called photoacoustic imaging to visualize light-absorbing tissue structures, such as the microvasculature Ultrasound-enhanced drug delivery and advanced probe design and signal processing for improved sensitivity and resolution in ultrasound images