| |
|
|
| |
Ocular Electrophysiology (Electrodiagnostics) |
|
| |
|
|
| |
Electrophysiological examination provides objective information
in relation to the function of the visual pathway helping in diagnosis
and management of the patient. The main tests are Electro-retinogram
(ERG), Visual evoked potential (VEP) and Electro-oculogram (EOG).
These are used to locate the site of disease whether in the retina,
optic nerve or brain, and to decide the extent of disease. They
help to decide the potential for visual recovery and appropriate
treatment. Light stimulus produces electrical waveforms and the
machine picks up the waveforms and displays it on a monitor and
as printout. Shroff Eye Centre offers you a dedicated Ocular Electrodiagnostics
Service for the diagnosis of disorders related to the visual pathway.
|
|
| |
|
|
| |
The following tests are available:
The Electro-Retinogram (ERG)
The Visual Evoked Potential (VEP)
The Electro-oculogram (EOG)
|
|
| |
|
|
| |
The Electro-Retinogram (ERG) |
|
| |
The ERG is the mass electrical response of retina in response to
a bright flash of light and is recorded using corneal electrodes.
It reflects the function of the retinal photoreceptors (rods and
cones) and the inner nuclear layers of retina. It is often useful
for:- " Diagnosing and predicting outcome of inherited retinal degeneration.
Early diagnosis of retinal degeneration in children with family
history of inherited retinal degeneration.
Differentiating types of retinal degeneration (cone-rod, rod-cone
type).
Prognosticating high risk characteristics in cases of central retinal
vein occlusion.
Unexplained vision loss
|
|
| |
|
|
| |
The Visual Evoked
Potential (VEP) |
|
| |
VEP measures the electrical responses generated at visual cortex
in response to a visual stimulus with the help of electrodes. It
is helpful in:
Optic nerve disease
Cortical Blindness
Visual assessment in preschool children
Malingerers
Amblyopia
A special type of flash VEP is helpful in cases with media opacity
as a rough method to indicate that light is perceived.
|
|
| |
Go back
to the top » |
|
| |
The Electro-oculogram
(EOG) |
|
| |
 This
test examines the function of the retinal pigment epithelial cells
(RPE). When this layer is healthy a standing potential is established
between the front and the back of the eye that responds to change
in background illumination. The standing potential can be measured
by measuring the voltage induced across a pair of electrodes put
around the eye as the eye looks from side to side. The test is most
useful for a hereditary retinal degeneration called Best's disease.
|
|
| |
|
|
| |
|
|
| |
For further details, contact The Neuro-Ophthalmology
& Electrodiagnostics Service at Shroff Eye Centre |
|
| |
|
|
| |
Go back
to the top » |
|
