The nGoggle: A Portable Brain-Based Method for Assessment of Visual Function Deficits in Glaucoma

Abstract

Purpose : To describe the development of a new portable objective method for assessment of functional deficits in glaucoma. The device is armed with electrophysiological sensors, mA current stimulators and wireless fog/cloud computing support to enable portable and objective assessment of visual field defects using multifocal steady-state visual-evoked potentials (mfSSVEPs).

Methods : A prototype has been developed by adding the following sensors, actuators and processors to a Samsung Gear VR Goggle (Figure 1): Six EEG dry electrodes at Oz, O3, O4, Pz, left and right mastoids with the Reference at Fz; Three EEG/EOG/EMG electrodes at FPz and the inner corners of lower eyelids; Dual-band 602.11 a/b/g/n Wi-Fi and Bluetooth 4.0 radios; Dual-core processor running Yocto Linux with Preempt-RT patch. Artifact removal, spectral and canonical correlation analyses can be run in the embedded processor in near real time. Gaussian pseudo-random current noise of ±1mA can be injected through four electrodes at Fz, Oz, left and right mastoids. The frontend device is supported by a pervasive computing infrastructure consisting of near-end fog servers and far-end cloud computing centers. EOG captured around the perimeters of subjects’ eyes was used to monitor the dynamics of eye saccade and fixation losses. Multiple frequency-tagged flickering sectors (alternating black/white) are presented in order to elicit mfSSVEP signals. All sectors flickered concurrently at frequencies from 8 to 11.8 Hz with a step of 0.2 Hz.

Results : Figure 2 shows the waveforms and power spectra of EEG/EOG signals (10 Sec epochs) collected in an experimental subject using the prototype, indicating reliable capture of mfSSVEP and EOG signals.

Conclusions : In initial development and experimental testing, the system was able to reliably capture and analyze visually induced-mfSSVEP signals and electrooculogram signals on the fly. The portability and wireless cloud-based signal transmission capability may enable in-home and remote objective testing of visual function deficits with this system.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

The nGoggle