Electrophysiology and Glaucoma Research

Group leader

Group Members

Alex Klistorner
BMed PhD, Unit Co-Head
Stuart Graham
PhD MBBS MS FRANZCO FRACS, Unit Co-Head
John Grigg
MBBS FRANZCO FRACS
Frank Billson
MBBS FRANZCO FRACS FAC FRCOphth
Alessandra Martins
MBBS, Postgraduate Student
Hemamalini Srinivasan
Glaucoma Clinical Fellow,  Sydney Eye Hospital
Asya Klistorner
BMed Sci, Electrophysiology Technician
Dr Maria Kosokova
Electrophysiology Technician

Research Activity

The electrophysiology unit continues to provide clinical testing as well as research into new techniques for electrodiagnosis, especially for the detection of glaucoma. In 2005 the department acquired a new electrodiagnostic system, the Espion Diagnosys system. The Espion system was designed to easily perform all the current standard clinical visual function tests, including ERG, VEP, PERG, EOG, Flash-VEP and Pattern VEP. The Espion Diagnosys System comes programmed with the ISCEV standards as well as allowing modifications for research. It also has a hand-held mini ganzfeld which is useful for testing children. It enables testing of children without the need for sedation. Following acquisition of a normative database for the tests from the local population the system has provided a more reliable and sensitive system for detailed assessment of patient’s visual function.

Projects

Development of Objective Perimetry – the Multifocal Visual Evoked Potential

Klistorner, Graham, Grigg, Billson

The Save Sight Institute continues to work on development of multifocal Visual Evoked Potentials. A new binocular system, incorporating dual LCD monitors was designed and built in cooperation with Macquarie University. The system will allow eye monitoring, which was not possible previously and is therefore expected to improve accuracy of binocular mfVEP.

Development of a Blue/Yellow Multifocal Visual Evoked Potential

Martins, Klistorner, Graham, Arvind

Research is also continues into use of blue-yellow stimuli for presenting the multifocal Visual Evoked Potential (mVEP) in an attempt to detect glaucoma at an earlier stage. The rationale for this is that in subjective perimetry blue/yellow testing has been shown to be more effective at detecting early disease. To date, the mVEP technique has used a black and white stimulus to demonstrate abnormal visual field defects in glaucoma cases. A study was completed in 2009 investigating the power of Blue-on-Yellow mfVEP in detecting pre-perimetric glaucoma. The technique demonstrated high sensitivity in cases where subjective perimetry was still normal. Longitudinal (5 years) research is now underway to investigate the predictive power of Blue-on-Yellow mfVEP in glaucoma as compared to other structural and functional methods.

Multifocal Visual Evoked Potentials in Optic Neuritis

Grigg, Klistorner, Graham, Garrick, Arvind

Multiple Sclerosis (MS) can damage the optic nerve leading to vision loss; this can be the first presentation of MS in 30% of patients. The resulting optic neuritis causes the loss of the protective layer surrounding the nerve fibres. Consequently there is a disruption in the electrical signal transmitted from the eye to the brain. Visual Evoked Potentials (VEPs) record the electrical responses in the brain that represent the transmission of this visual information from the eye. We conducted a study in 2009 looking at demyelination in the optic nerve after episodes of optic neuritis and possible mechanisms which may affect remyelination and are currently investigating the relationship between inflammation, demyelination and axonal loss using optic neuritis as a model of multiple sclerosis.