Assistant Professor of Ophthalmology
Dr. Gramatikov has been a member of the Hopkins faculty since 1996, and is currently Assistant Professor in the Division of Pediatric Ophthalmology and Adult Strabismus at the Wilmer Eye Institute. He is a biomedical engineer with expertise in medical instrumentation, electronic hardware, optoelectronics, medical optics, computer software, signal processing, computer modeling and data analysis. His current research interests are in focus detection and retinal birefringence scanning, including transition from the laboratory bench to clinical settings. The main goal is to identify and treat children with strabismus (misaligned eyes) or anisometropia (unequal refractive error) before irreversible amblyopia (functional monocular blindness) results.
Dr. Gramatikov is the 2006 Past Chair of the Baltimore Section of the IEEE (Institute of Electrical and Electronics Engineers). Presently he is the Section's Director for Education Activities and Continuing Education. He has also chaired the Baltimore Chapter of the IEEE-EMBS (Engineering in Medicine and Biology Society).
In 2009 Dr. Gramatikov received the The Hartwell Foundation Individual Biomedical Research Award for work on the Pediatric Vision Screening Instrument for Early Detection of Amblyopia (Lazy Eye). Read the related article in the JHU Gazette…
Dr. Gramatikov and team recently received a Biomedical Research Collaboration Award from the Hartwell Foundation for developing advanced technology for diagnosing retinal abnormalities in infants and toddlers, in collaboration with Duke University. Read the JHU announcement.
Retinal birefringence scanning utilizes the optical polarization properties of the human retina. This method was developed originally by Dr. David Guyton and Dr. David Hunter ("Automated detection of eye fixation by use of retinal birefringence scanning", Applied Optics 38,OT&BO:1273-9, March 1999), and is related to the Haidinger brush phenomenon - a bow-tie or propeller-like pattern that appears to rotate about the fixation point when a polarizing filter is placed over the eye and rotated. This phenomenon reflects the retinal nerve fiber axon arrangement about the fovea and can be utilized in a variety of useful applications. In our settings, foveal fixation is monitored in human subjects remotely and continuously by use of a noninvasive retinal scan. Polarized near-infrared light is imaged onto the retina and scanned in a 3-deg annulus at frequency f. Reflections are analyzed by differential polarization detection. The detected signal is predominantly of frequency 2f during central fixation, and f during paracentral fixation. Phase shift at f correlates with the direction of eye displacement. Mathematical modeling of birefringence in retinal birefringence scanning has confirmed the experimental and clinical results. Potential applications of this technique include screening for eye disease, eye position monitoring during clinical procedures, and use of eye fixation to operate devices. Considering that the structure of the fovea is the basis of the retinal birefringence scan signal, the experience gained from bringing retinal birefringence scanning to the clinic will also increase our understanding of foveal structure in health and other forms of disease. Dr. Gramatikov is involved in the design of a portable Bilateral Retinal Birefringence Scanner (BRBS) with improved noise performance, to be used as a pediatric vision screener. The new design incorporates binocular foveal birefringence scanning, and separate channels for binocular focus detection. This combination of focus and alignment detection should identify over 95% of all children at risk for amblyopia. This work is being performed in the past in collaboration with AURA (Association of Universities for Research in Astronomy, Inc.), the Space Telescope Science Institute and the Instrument Development Group (IDG) at the Department of Physics and Astronomy at the Johns Hopkins University. This project was supported generously by The Hartwell Foundation with the 2009 Individual Biomedical Research Award.
Retinal birefringence scanning and optical coherence tomography.This is a collaboration project between Johns Hopkins and Duke University, sponsored by The Hartwell Foundation. Both PIs, Dr. Cynthia Toth and Dr. Boris Gramatikov, have successfully completed previous individual research projects sponsored by the foundation. The goal of the present research project is to improve these two technologies and possibly combine them with the aim of improving the current ability to determine levels of retinal disease in infants and children and to better identify likelihood of disease progression.
Determination of ocular defocus using the double-pass blur image of a point source of light. The double-pass blur image of a point source is used to determine the quality of focus of the human eye. This project is based on earlier work by Dr. David Guyton, Dr. David Hunter and Nainesh Gandhi. An apparatus that can determine a threshold of defocus was devised using a circle/annulus (bulls-eye) photodiode that can distinguish focused from defocused light. A monochromatic near-infrared light source (laser diode) is employed. The light reflected from the fundus of the eye is projected by a beamsplitter onto the bulls-eye detector, which is optically conjugate to the laser diode. The photodetector signal obtained is a function of the amount of defocus caused by the double-pass point spread reflected from the retina. The signal is affected by refractive error, incomplete accommodation, media opacities, and abnormalities of retinal reflection. One of the major risk factors for amblyopia is refractive error, or, more accurately, the degree of defocus the eye experiences. The defocus is perhaps best quantified by measuring the size of the retinal blur circle. Such defocus detection can be combined with eye-fixation monitoring to be used as a screening tool to detect risk factors for amblyopia.