Boris_2009        Boris Gramatikov, Ph.D.


 

I am a member of the Hopkins faculty since 1996, and am currently Assistant Professor in the Division of Pediatric Ophthalmology and Adult Strabismus at The Wilmer Eye Institute. I am a biomedical engineer with expertise in medical instrumentation and signal processing. My present research interests are in retinal birefringence scanning and automated focus detection, 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. Click here for more on Clinical Technology Development at our Division.

Please click here for my web page at the Wilmer Eye Institute.

I have chaired the Baltimore Chapter of the IEEE-EMBS (Institute of Electrical and Electronics Engineers, Engineering in Medicine and Biology Society), which is a part of the Baltimore Section of the IEEE. I chaired the Section in 2006, and am presently an ExCom member and The Section’s Director for Education Activities and Continuing Education (CEEE). Click here for a list of past and planned future CEEE events. I have also chaired the Baltimore Chapter of the IEEE-EMBS (Engineering in Medicine and Biology Society).

In 2009 I 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 

I and my co-workers 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.  Read more  

Current projects
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 further improve these two technologies and combine them with the aim of enhancing 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.  

More about me

The Pediatric Vision Screener – early prototype (2000-2001)

 
Current work on the Pediatric Vision Screener

Using computer modeling, optical technologies, modern electronic hardware, novel signal processing and optimization methods, we are presently redesigning and reconstructing the Pediatric Vision Screener, with the goal of making it a clinically relevant, market-oriented and competitive product.

Some spin-off products: a vision scanner using non-moving parts, a biometric (security) scanner using the birefringent properties of the retina, and others (please see publications).

More about me:

 


This page was last updated on Aug 30, 2013