Learn Electroretinography mcq (ERG), Electrooculography (EOG), and Visual Evoked Potential (VEP) with 40 exam-based MCQs and detailed explanations. Covers ERG waves, Arden ratio, RPE function, VEP P100 latency, and diagnostic differences between retinal, optic nerve, and cortical visual disorders — essential for NEET PG, AIIMS, and ophthalmology exam preparation.
Electroretinography (ERG)
1. ERG measures the function of:
A. Optic nerve
B. Retina
C. Visual cortex
D. Lens
View Answer
B. Retina ✅ Exp: ERG records retinal electrical activity in response to light.
2. The main waveforms of ERG are:
A. a-wave, b-wave
B. P100 wave
C. Alpha, beta waves
D. Hippus wave
View Answer
A. a-wave, b-wave ✅ Exp: a-wave (photoreceptors), b-wave (Müller & bipolar cells).
3. The a-wave of ERG represents activity of:
A. Photoreceptors
B. Bipolar cells
C. Ganglion cells
D. RPE
View Answer
A. Photoreceptors ✅ Exp: a-wave = negative deflection from photoreceptors.
4. The b-wave of ERG originates from:
A. Müller & bipolar cells
B. Photoreceptors
C. Ganglion cells
D. Optic nerve
View Answer
A. Müller & bipolar cells ✅ Exp: Positive deflection, inner retina response.
5. c-wave of ERG originates from:
A. RPE
B. Ganglion cells
C. Müller cells
D. Lens
View Answer
A. RPE ✅ Exp: Generated by RPE and Müller cells.
6. Normal ERG is extinguished in:
A. Retinitis pigmentosa
B. Optic neuritis
C. Cataract
D. Glaucoma
View Answer
A. Retinitis pigmentosa ✅ Exp: Rod-cone degeneration → flat ERG.
7. ERG is normal in:
A. Optic nerve diseases
B. Retinitis pigmentosa
C. Cone dystrophy
D. CSNB (congenital stationary night blindness)
View Answer
A. Optic nerve diseases ✅ Exp: ERG tests retina, not optic nerve.
8. Photopic ERG tests:
A. Cones
B. Rods
C. Bipolar cells only
D. Optic nerve
View Answer
A. Cones ✅ Exp: Done in light → cone function.
9. Scotopic ERG tests:
A. Rods
B. Cones
C. RPE
D. Optic nerve
View Answer
A. Rods ✅ Exp: Dark-adapted ERG → rod function.
10. ERG is useful in diagnosis of:
A. Retinitis pigmentosa
B. Glaucoma
C. Optic neuritis
D. Cataract
View Answer
A. Retinitis pigmentosa ✅ Exp: Detects rod-cone dystrophy.
Electrooculography (EOG)
11. EOG records electrical activity of:
A. Retina
B. RPE
C. Lens
D. Optic nerve
View Answer
B. RPE ✅ Exp: EOG measures potential between cornea and retina, mainly RPE function.
12. The normal Arden ratio (light/dark ratio) is:
A. >180%
B. >200%
C. >1.85 (185%)
D. <1.0
View Answer
C. >1.85 (185%) ✅ Exp: Normal EOG = Arden ratio ≥185%.
13. Subnormal EOG is seen in:
A. Best’s disease
B. Optic neuritis
C. Retinitis pigmentosa
D. Cataract
View Answer
A. Best’s disease ✅ Exp: Best’s vitelliform macular dystrophy shows abnormal EOG.
14. In Best’s disease, ERG is:
A. Normal
B. Absent
C. Extinguished
D. Reduced
View Answer
A. Normal ✅ Exp: ERG normal but EOG abnormal.
15. EOG light peak arises due to:
A. RPE function
B. Müller cells
C. Photoreceptors
D. Ganglion cells
View Answer
A. RPE function ✅ Exp: RPE activity increases corneoretinal potential in light.
16. EOG is normal in:
A. Optic nerve disease
B. Best’s disease
C. Cone dystrophy
D. RPE dystrophy
View Answer
A. Optic nerve disease ✅ Exp: RPE must be intact for normal response.
17. Arden ratio is reduced in:
A. Best’s disease
B. Retinitis pigmentosa
C. Stargardt’s disease
D. All of the above
View Answer
D. All of the above ✅ Exp: Several RPE disorders show low Arden ratio.
18. Which is more sensitive for RPE dysfunction?
A. ERG
B. EOG
C. VEP
D. OCT
View Answer
B. EOG ✅ Exp: EOG specifically assesses RPE integrity.
19. EOG is recorded in:
A. Darkness & light
B. Only light
C. Only dark
D. With visual evoked stimulus
View Answer
A. Darkness & light ✅ Exp: Compares dark trough and light peak.
20. Arden ratio compares:
A. Light peak to dark trough
B. a-wave to b-wave
C. ERG to VEP
D. Cones to rods
View Answer
A. Light peak to dark trough ✅ Exp: Ratio used to quantify RPE activity.
Visual Evoked Potential (VEP)
21. VEP measures activity of:
A. Retina
B. Optic nerve → visual cortex
C. RPE
D. Lens
View Answer
B. Optic nerve → visual cortex ✅ Exp: Records cortical response to visual stimulus.
22. The most important VEP wave is:
A. a-wave
B. b-wave
C. P100
D. N1
View Answer
C. P100 ✅ Exp: P100 latency is most consistent and clinically useful.
23. Delayed P100 latency in VEP is seen in:
A. Optic neuritis
B. Retinitis pigmentosa
C. Best’s disease
D. Cataract
View Answer
A. Optic neuritis ✅ Exp: Demyelination delays conduction → optic neuritis.
24. VEP is abnormal in:
A. Optic nerve disease
B. Cortical blindness
C. Both A & B
D. Retinitis pigmentosa
View Answer
C. Both A & B ✅ Exp: VEP evaluates post-retinal visual pathway.
25. Normal VEP with poor vision suggests:
A. Non-organic visual loss
B. Optic neuritis
C. Retinitis pigmentosa
D. RPE dysfunction
View Answer
A. Non-organic visual loss ✅ Exp: Functional vision loss shows normal VEP.
26. Flash VEP is used in:
A. Uncooperative patients & infants
B. Adults with normal vision
C. Only macular disorders
D. ERG abnormalities
View Answer
A. Uncooperative patients & infants ✅ Exp: Flash VEP doesn’t require fixation.
27. Pattern VEP assesses:
A. Macular & optic nerve function
B. Peripheral retina
C. Lens
D. Vitreous
View Answer
A. Macular & optic nerve function ✅ Exp: Requires fixation, central visual function tested.
28. Absent VEP with extinguished ERG suggests:
A. Retinal disease
B. Optic nerve disease
C. Cortical disease
D. Refractive error
View Answer
A. Retinal disease ✅ Exp: Both abnormal → retinal origin.
29. Normal ERG but abnormal VEP suggests:
A. Optic nerve disease
B. Retinal disease
C. RPE disease
D. Vitreous degeneration
View Answer
A. Optic nerve disease ✅ Exp: Retinal function intact, conduction defect post-retinal.
30. Normal VEP with abnormal ERG suggests:
A. Retinal disease
B. Optic nerve disease
C. Cortical blindness
D. Functional loss
View Answer
A. Retinal disease ✅ Exp: Retinal dysfunction, optic nerve & cortex intact.
31. ERG extinguished but VEP normal in:
A. Retinitis pigmentosa
B. Optic neuritis
C. Cortical blindness
D. Functional vision loss
View Answer
A. Retinitis pigmentosa ✅ Exp: RP affects photoreceptors, optic nerve intact.
32. ERG normal but VEP abnormal in:
A. Optic neuritis
B. RP
C. Best’s disease
D. Cataract
View Answer
A. Optic neuritis ✅ Exp: Post-retinal conduction defect.
33. Both ERG & VEP abnormal in:
A. Leber’s congenital amaurosis
B. Optic neuritis
C. Cortical blindness
D. Best’s disease
View Answer
A. Leber’s congenital amaurosis ✅ Exp: Diffuse retinal + optic nerve involvement.
34. EOG abnormal with normal ERG in:
A. Best’s disease
B. Retinitis pigmentosa
C. Stargardt’s
D. Glaucoma
View Answer
A. Best’s disease ✅ Exp: Classic finding.
35. VEP is normal in:
A. Functional visual loss
B. Optic neuritis
C. Cortical blindness
D. Amblyopia
View Answer
A. Functional visual loss ✅ Exp: Confirms malingering.
36. Delayed VEP P100 latency suggests:
A. Demyelination (e.g., MS, optic neuritis)
B. Retinal dystrophy
C. Cataract
D. Corneal opacity
View Answer
A. Demyelination (e.g., MS, optic neuritis) ✅ Exp: Slowed conduction along optic nerve.
37. ERG is useful in differentiating:
A. Retinal vs optic nerve disease
B. Lens vs vitreous disease
C. RPE vs cornea disease
D. Glaucoma vs cataract
View Answer
A. Retinal vs optic nerve disease ✅ Exp: ERG normal in optic nerve disease.
38. Abnormal Arden ratio indicates:
A. RPE dysfunction
B. Optic nerve lesion
C. Retinal ganglion cell loss
D. Vitreous opacity
View Answer
A. RPE dysfunction ✅ Exp: Specific for RPE.
39. EOG & ERG both normal, but VEP abnormal suggests:
A. Optic nerve disease
B. Retinitis pigmentosa
C. Best’s disease
D. Vitamin A deficiency
View Answer
A. Optic nerve disease ✅ Exp: Confirms conduction defect post-retinal.
40. Which test best localizes optic nerve conduction defects?
A. ERG
B. EOG
C. VEP
D. OCT
View Answer
C. VEP ✅ Exp: VEP specifically tests optic nerve → cortex.
