1. **Electro-physiology and Vision:** - Electro-physiology refers to the study of electrical activity in biological tissues. - In the context of vision, the electrical signals generated by different layers of the retina play a crucial role. - These signals are essential for the transmission of visual information to the brain. 2. **Layers of the Retina:** - The retina, located at the back of the eye, consists of multiple layers that contribute to the visual process. - The passage suggests that electro-physiology helps in understanding the functioning of these different layers. 3. **Detection of Media Opacity:** - Media opacity refers to any obstruction or clouding in the eye's optical media (such as the cornea or lens). - Electro-physiological tests can be used to detect and assess the impact of media opacity on the transmission of visual signals. 4. **Pathology Severity Assessment:** - Electro-physiology aids in evaluating the severity of pathological conditions affecting the retina. - It provides insights into the extent of damage or dysfunction in different layers of the retina. 5. **Afferent and Efferent Pathways:** - Afferent pathways involve the transmission of sensory information (in this case, visual signals) from the eye to the brain. - Efferent pathways involve signals traveling from the brain to the eye. - Electro-physiology allows for the examination of both pathways, providing a comprehensive assessment of the visual system. 6. **Pediatric Age Groups:** - Electro-physiological tests are not limited to adults; they are also applicable and valuable for evaluating the visual system in pediatric age groups. - This suggests that these tests can be used to assess the development and health of the visual system in children. 7. **Malingering Detection:** - Malingering refers to the intentional exaggeration or feigning of symptoms. - Electro-physiological tests can be used to rule out malingering by objectively measuring the electrical activity associated with vision, providing more reliable results. In summary, electro-physiology plays a crucial role in understanding the complex mechanisms of vision, assessing the health of the retina, and diagnosing and monitoring various eye conditions, including those in pediatric populations. It also serves as a valuable tool for objective testing, particularly in cases where malingering is a concern.

1. Electrophysiology
By
Optom.Shoubhik Chakraborty
Pediatric Optometrist
Kalinga Institute of medical science

2. Electrodiagnostic: Visual electrodiagnostic are painless, non-invasive tests that
measure the function of the retina and optic nerve.
Visual transduction is the process by which light absorbed by the outer segment of the
photoreceptor layer of the retina is converted into electrical energy

3. Full pupillary
dilatation
30 minutes of
dark adaptation
Rod response
Maximum
combined
response
10 m of light
adaptation
Single flash cone
response
30 hz flicker
Reading protocol of ERG
1. A- wave: From the cones and
rods, negative response
2. B-wave: Amacrine, horizontal
,bipolar and muller ,positive
response
3. C-wave: Derived from RPE
4. D-wave: Represent feedback of
bipolar-amacrine cells
interactions

4. Full Field
ERG(Total
retinal
function by
flash of 5ms)
Focal
ERG(Local
measures of
4* area of
retina)
Multifocal(Bla
ck and white
hexagonal
elements to
measure
multifocal
lesions )
Pattern
ERG(Especi
ally ganglion
cell activity)

6. Electro-oculogram
Clinical measurement of integrity of retinal epithelium layers, EOG measures the
standing potential between the electrical +ve cornea and electrical –ve back of the eye.
During 15 min of dark
adaptation the standing
potential usually reaches a
minimum level (dark trough/DT)
at 10-15 min. During 15 min of
light adaptation the standing
potential achieves the highest
value at 7-12 min called a light
peak/LP

7. Normal arden ratio: >1.80
Boderline arden ratio: 1.65-1.85
Subnormal arden ratio: <1.65

8. The VEP test measures field potentials that originate during cortical processing of the
visual data received from the afferent visual pathway. On one hand, this electrical
activity reflects the events of visual processing in the primary visual cortex, but on the
other hand, it also reflects the integrity of all neural structures in the afferent pathway
from the photoreceptor layer of the retina to the cortex of the occipital lobe.
Visual evoked potential
Frequently relevant response components include a positive peak at about 100
ms and a negative peak at about 150 ms

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1). Lippincott Williams & Wilkins.
2. Brodsky, M. C., Baker, R. S., Hamed, L. M., & Flynn, J. T. (2010). Pediatric neuro-ophthalmology (p. 8). New
York: Springer.
3. Glaser, J. S. (Ed.). (1999). Neuro-ophthalmology. Lippincott Williams & Wilkins.
4. Miller, N. R. (2011). Functional neuro-ophthalmology. Handbook of clinical neurology, 102, 493-513.
5. Pane, A., Miller, N. R., & Burdon, M. (2017). The neuro-ophthalmology survival guide. Elsevier Health
Sciences.
6. International Society for Clinical
7. International Society for Clinical Electrophysiology of Vision (ISCEV) standard
8. Whatham, A. R., Nguyen, V., Zhu, Y., Hennessy, M., & Kalloniatis, M. (2014). The value of clinical
electrophysiology in the assessment of the eye and visual system in the era of advanced imaging. Clinical
and Experimental Optometry, 97(2), 99-115.
9. Eye-wiki Thank You…