University of Southern California Department of Biomedical Engineering The USC Andrew and Erna Viterbi School of Engineering USC
Biomedical Engineering and Research

           

Current Research Projects:

 

Oxygen Therapy for the Treatment of Retinal Ischemia

  The Response of Retinal Bipolar Cells to Electrical Stimulation
  Wireless Implantable Bioelectronic System for Neuroscience Research
  Evaluation of Electrical Stiumuation of the Retina with Optical Coherence Tomography
 

Transcranial photon propagation with distributed near infrared light sources

  Novel nanophotoswitches (NPSs) for vision restoration  
 

Physiologic effects of the bioelectronic visual implant after prolonged chronic electrical stimulation 

  BioFlex Smart Shunt for Presymptomatic Detection of Ventricular Shunt Obstruction 
 

Computer Vision Aided Object Localization for the Visually Impaired 

  Electrode-tissue interface of retinal prosthesis  
   Mobility Feedback in Wearable Visual Aids
 

 

   


 

Research Overview


Oxygen Therapy for the Treatment of Retinal Ischemia

 
Retinal vascular diseases are amongs the leading causes of blindness. Diabetic Retinopathy and Retinal Vein Occlusions are common retinal vascular diseases in which hypoxia secondary to retinal ischemia leads to retinal cell death. We are developing a new oxygen therapy to treat retinal ischemia.
 

 

Graduate Student: Karthik Murali
Collaborator: Dr Mark Humayun
Funding: National Institutes of Health (NIH), Harrington Foundation, Whittier Foundation, Research to Prevent Blindness
 

The Response of Retinal Bipolar Cells to Electrical Stimulation

This project focuses on determining the response of retinal bipolar cells to extracellular electrical stimulation in normal and degenerate retina.  Patch clamp recordings are made from individual bipolar cells in the wholemount retina while electrically stimulating the retina with an extracellular electrode.  Results from this study will help determine optimal stimulation protocols for activating the inner retina.
 

 

 
Graduate Students: Steven Walston

Collaborator: Dr. James Weiland,
Funding: National Eye Institute (NEI), The National GEM Consortium, National Science Foundation (NSF), Research to Prevent Blindness, W.M. Keck Foundation

 

Wireless Implantable Bioelectronic System for Neuroscience Research 

This is a collaborative project focused on developing an implantable system to interface with neuronal circuitry of small animals such as rats for applications in neuroscience research. The system will include two arrays of electrodes for bidirectional communication: namely stimulation and recording. It will also allow stimulation signals to be configured and recording data to be received wirelessly so the animal can be free roaming during the experiments.
 

 

 
Graduate Students: Sahar Elyahoodayan
Collaborators: Dr. James Weiland,
Funding: Integrated NSF Support Promoting Interdisciplinary Research and Education (INSPIRE)
 

Evaluation of Electrical Stiumuation of the Retina with Optical Coherence Tomography

 
Retinal prostheses have been tested in blind humans and have demonstrated the capability to elicit the sensation of light and to give test subjects the ability to detect motion. To be able to achieve a high resolution retinal prostheses, simulations of artificial vision suggest that 600-1000 electrodes will be required and round focal percepts need to be elicited for patients to be able to identify complex shapes. Some studies have shown that long pulse stimulation can be used to achieve focal vision targeting bipolar cells without axonal stimulation in patients with RD (Retinal Degeneration) diseases. Safety is a concern because long pulses require more charge than short pulses to have the same effect on neural tissue. The experiment proposed will be assessing the efficacy and safety of long pulses and high charge density pulses in vivo in rabbits.
 

 

 
Graduate Students: Alejandra Gonzalez Calle
Collaborator: Dr. James Weiland
Funding:
 

Transcranial photon propagation with distributed near infrared light sources

 
The main goal of the overall project is to develop custom-made molecules that can be released into the brain by transcranial Near infrared (NIR) irradiation. NIR light undergoes significant attenuation after penetrating through layers of head tissues therefore it is difficult to safely provide sufficient photon energy at brain depth with a single light source. Here we systematically investigated intracranial photon flux enhancement produced by distributed multi-source array using Monte Carlo simulation and finite element analysis of light propagation in a human head. 
 

 

 
Post Doc: Dr Lan Yue
Collaborator: Dr. Mark Humayun
Funding: Keck Foundation
 

Novel nanophotoswitches (NPSs) for vision restoration  

 
Nanophotoswitch (NPS) offers a new tool to elicit electrical activity for basic science studies of neuronal function, both in vitro and also potentially in vivo. The goal of this project is to investigate the possibility of using NPS as a molecular visual prosthesis to restore sights in the blind. The light-elicited electrophysiological activity of NPS is examined in degenerate retina and the retinal localization of the intravitreally injected NPS is determined with two photon imaging.
 

 
Post Doc: Dr Lan Yue
Collaborator: Dr. Mark Humayun
Funding: National Science Foundation (NSF)
 

Physiologic effects of the bioelectronic visual implant after prolonged chronic electrical stimulation 

 
Bioelectronic epiretinal implants that bypass the photoreceptor layer and directly stimulate the neural retina restore a limited sense of sight to retinitis pigmentosa patients that have been blind for decades. The goal of this study is to investigate the physiologic effects of Argus I, the first-generation epiretinal prosthesis, in RP patients after extended period of implantation as long as 10 years. Performance of the electronic system, implant-retina physical interface and the subjects' visual responses are examined and analyzed. 
 
Post Doc: Dr Lan Yue
Collaborator: Dr Mark Humayun
Funding: Research to Prevent Blindness (RPB)
 

BioFlex Smart Shunt for Presymptomatic Detection of Ventricular Shunt Obstruction

 
The BioFlex system is a collection of flexible, impedance based sensors that measure pressure, flow, and occlusion in ventricular shunts used to treat hydrocephalus. Hydrocephalus is a disease characterized by excess cerebral spinal fluid (CSF) and pressure in the brain, which affects 1 to 2 out of every 1000 births and leads to brain damage and death. Ventricular shunts are used to drain excess CSF from the brain into the abdominal cavity or heart; however, 40% of shunts to fail in the first year and 80% of shunts to fail by year 10, mostly due to obstruction. Shunt failure is currently detected only after patients report non-specific flu-like symptoms. The BioFlex will be placed in-line with shunts to monitor progressive obstruction so they can be replaced before symptoms occur and neurosurgeons can gain a better understanding of shunt failure in order to improve treatment. 

 

 
Post Doc: Dr Curtis Lee
Collaborator: Dr. James Weiland
Funding:
 

Computer Vision Aided Object Localization for the Visually Impaired 

 
The main purpose of this project is to create and test a system which aids the blind in looking for useful and important objects.  This is accomplished by utilizing computer vision algorithms, and computerized speech synthesis for recognizing, tracking and communicating spoken commands to the visually impaired subject.  The end goal is to assist these visually impaired subjects with doing daily tasks such as grocery store shopping.
 
Graduate Student: Nii Mante
Collaborator: Dr James Weiland
Funding: TATRC

 Electrode-tissue interface of retinal prosthesis

 
This project aims to understand how the electrical field interacts between the electrodes and the retinal tissue, and how this affect neuronal stimulation. The measurement data from this study provides inputs for computational modeling and validates prediction of the models.
 Graduate Student: Boshuo Wang
Collaborator: Dr James Weiland
Funding: National Institutes of Health

 Mobility Feedback in Wearable Visual Aids

 

 The main goal of this project is to address the user-interface considerations of providing mobility feedback in a wearable visual aid. Proper execution of directional information while navigating freely directly affects the safety of the user, therefore it is essential that the information provided is second-nature to the end-user. This is accomplished by assessing the usability of mobility feedback through a variety of modalities, the automation of proficient response to directional information, and the design of an adaptive control algorithm that provides this directional information. 
 
 
 Graduate Student: Aminat Adebiyi
Collaborator: Dr James Weiland
Funding: The Telemedicine and Advanced Technology Research Center (TATRC)