Comprehensive MCQs on retina and phototransduction with answers and explanations. Covers retinal structure, photoreceptors, RPE, visual pathways, ERG, and common retinal disorders. Ideal for NEET PG, USMLE, ophthalmology, ophthalomic officer exams and physiology exam preparation. visit our index page to find ophthalmology and optometry mcq.
Retinal Structure & Function
1. The retina is derived embryologically from:
A. Mesoderm
B. Ectoderm
C. Neuroectoderm
D. Endoderm
View Answer
C. Neuroectoderm ✅ Exp: Retina develops from neuroectoderm of optic cup.
2. The fovea centralis is specialized for:
A. Night vision
B. Color and fine vision
C. Peripheral vision
D. Motion detection
View Answer
B. Color and fine vision ✅ Exp: Fovea has only cones → highest visual acuity & color vision.
3. Total number of photoreceptors in human retina:
A. ~10 million
B. ~50 million
C. ~120 million rods + 6 million cones
D. ~200 million
View Answer
C. ~120 million rods + 6 million cones ✅ Exp: Retina has ~126 million photoreceptors.
4. Which retinal layer contains photoreceptor nuclei?
A. Inner nuclear layer
B. Outer nuclear layer
C. Ganglion cell layer
D. Plexiform layer
View Answer
B. Outer nuclear layer ✅ Exp: Outer nuclear layer contains rod and cone nuclei.
5. The photoreceptor outer segments are embedded in:
A. Retinal pigment epithelium
B. Inner nuclear layer
C. Ganglion cell layer
D. Bruch’s membrane
View Answer
A. Retinal pigment epithelium ✅ Exp: RPE maintains outer segments via phagocytosis.
6. The first retinal cells to generate an action potential:
A. Photoreceptors
B. Bipolar cells
C. Ganglion cells
D. Amacrine cells
View Answer
C. Ganglion cells ✅ Exp: Ganglion cells fire action potentials → optic nerve.
7. Retinal pigment epithelium (RPE) functions include:
A. Phagocytosis of outer segments
B. Absorption of stray light
C. Vitamin A metabolism
D. All of the above
View Answer
D. All of the above ✅ Exp: RPE maintains photoreceptor health.
8. Muller cells are:
A. Photoreceptors
B. Glial cells
C. Bipolar neurons
D. Ganglion cells
View Answer
B. Glial cells ✅ Exp: Muller cells provide structural and metabolic support.
9. The outer limiting membrane is formed by:
A. Tight junctions between Muller cells & photoreceptors
B. Basement membrane of RPE
C. Ganglion cell axons
D. Retinal blood vessels
View Answer
A. Tight junctions between Muller cells & photoreceptors ✅ Exp: Demarcates outer nuclear from inner segments.
10. Retinal blood supply:
A. Central retinal artery supplies outer retina
B. Choroid supplies outer retina
C. Both choroid & central artery supply equally
D. Retina is avascular
View Answer
B. Choroid supplies outer retina ✅ Exp: Outer 1/3 = choroid; inner 2/3 = central retinal artery.
Photoreceptor Physiology
11. Photopigment in rods:
A. Photopsin
B. Rhodopsin
C. Melanopsin
D. Iodopsin
View Answer
B. Rhodopsin ✅ Exp: Rhodopsin = visual purple, light-sensitive pigment.
12. Vitamin A deficiency leads to:
A. Night blindness
B. Photophobia
C. Color blindness
D. Glaucoma
View Answer
A. Night blindness ✅ Exp: Vitamin A is precursor of 11-cis-retinal.
13. Peak absorption of rhodopsin occurs at:
A. 400 nm
B. 507 nm
C. 600 nm
D. 700 nm
View Answer
B. 507 nm ✅ Exp: Rods are most sensitive to green-blue light.
14. Cone photopigments (iodopsins) are sensitive to:
A. Blue, green, red wavelengths
B. Blue only
C. Infrared
D. UV
View Answer
A. Blue, green, red wavelengths ✅ Exp: 3 cone opsins → trichromatic vision.
15. Which ion current maintains dark current in photoreceptors?
A. Sodium influx
B. Potassium efflux
C. Calcium influx
D. Chloride efflux
View Answer
A. Sodium influx ✅ Exp: In darkness, Na+ channels open → depolarization.
16. On exposure to light, photoreceptors:
A. Depolarize
B. Hyperpolarize
C. Fire action potentials
D. Remain unchanged
View Answer
B. Hyperpolarize ✅ Exp: Light closes Na+ channels → hyperpolarization.
17. The second messenger in phototransduction is:
A. cAMP
B. cGMP
C. IP3
D. DAG
View Answer
B. cGMP ✅ Exp: Light → cGMP breakdown → closure of Na+ channels.
18. Phototransduction cascade begins with:
A. Activation of transducin
B. Activation of cGMP phosphodiesterase
C. Sodium channel opening
D. ATP release
View Answer
A. Activation of transducin ✅ Exp: Rhodopsin activates transducin (G-protein).
19. The enzyme activated by transducin:
A. Adenylate cyclase
B. Guanylate cyclase
C. cGMP phosphodiesterase
D. Protein kinase C
View Answer
C. cGMP phosphodiesterase ✅ Exp: PDE hydrolyzes cGMP, closing Na+ channels.
20. Recovery of dark current requires:
A. Increased cGMP synthesis
B. Decreased Na+
C. Decreased K+
D. RPE breakdown
View Answer
A. Increased cGMP synthesis ✅ Exp: Guanylate cyclase resynthesizes cGMP.
Retinal Electrophysiology & Signal Processing
21. The first synapse in retina occurs between:
A. Photoreceptors & ganglion cells
B. Photoreceptors & bipolar cells
C. Ganglion & horizontal cells
D. Amacrine & RPE
View Answer
B. Photoreceptors & bipolar cells ✅ Exp: Photoreceptors transmit to bipolar cells.
22. Horizontal cells provide:
A. Lateral inhibition
B. Action potentials
C. Vitamin A transport
D. Phagocytosis
View Answer
A. Lateral inhibition ✅ Exp: Lateral inhibition sharpens visual contrast.
23. Amacrine cells function in:
A. Motion detection
B. Night vision
C. Phototransduction
D. Vascular regulation
View Answer
A. Motion detection ✅ Exp: Modify ganglion cell responses to motion.
24. Bipolar cells convey signals from:
A. Photoreceptors to ganglion cells
B. Ganglion to RPE
C. RPE to cones
D. Muller cells to rods
View Answer
A. Photoreceptors to ganglion cells ✅ Exp: Bipolar = first-order relay neurons.
25. Ganglion cell axons form:
A. Retinal blood vessels
B. Optic nerve
C. Choroid
D. Cornea
View Answer
B. Optic nerve ✅ Exp: Their axons converge at optic disc.
26. ON bipolar cells depolarize in:
A. Darkness
B. Light
C. Both
D. Neither
View Answer
B. Light ✅ Exp: ON cells respond to increased light.
27. OFF bipolar cells depolarize in:
A. Darkness
B. Light
C. Both
D. Neither
View Answer
A. Darkness ✅ Exp: OFF cells respond to decreased light.
28. Which retinal potential represents photoreceptor activity?
A. ERG a-wave
B. ERG b-wave
C. ERG c-wave
D. VEP
View Answer
A. ERG a-wave ✅ Exp: a-wave reflects rods/cones.
29. ERG b-wave arises mainly from:
A. Ganglion cells
B. Bipolar + Muller cells
C. RPE
D. Optic nerve
View Answer
B. Bipolar + Muller cells ✅ Exp: Bipolar cells generate b-wave.
30. Electro-oculogram (EOG) assesses:
A. Photoreceptor function
B. RPE function
C. Ganglion cell function
D. Optic nerve function
View Answer
B. RPE function ✅ Exp: EOG measures RPE potential.
31. Night blindness is first seen in:
A. Cone dysfunction
B. Rod dysfunction
C. Ganglion cell loss
D. RPE dysfunction only
View Answer
B. Rod dysfunction ✅ Exp: Rods mediate scotopic (dim light) vision.
32. Color blindness is due to:
A. Rod dysfunction
B. Cone pigment defect
C. Ganglion cell loss
D. RPE dysfunction
View Answer
B. Cone pigment defect ✅ Exp: Cone opsin deficiency → color blindness.
33. Most common type of color blindness:
A. Tritanopia
B. Deuteranopia
C. Protanopia
D. Achromatopsia
View Answer
B. Deuteranopia ✅ Exp: Red-green (deuteranopia > protanopia).
34. Blue-yellow color blindness occurs in:
A. Protanopia
B. Tritanopia
C. Deuteranopia
D. Achromatopsia
View Answer
B. Tritanopia ✅ Exp: Rare S-cone deficiency.
35. Central scotoma is typically due to:
A. Macular disease
B. Peripheral retinal detachment
C. Optic nerve head swelling
D. Corneal opacity
View Answer
A. Macular disease ✅ Exp: Macula → central vision loss.
36. Ring scotoma seen in:
A. Retinitis pigmentosa
B. Macular degeneration
C. Glaucoma
D. Optic neuritis
View Answer
A. Retinitis pigmentosa ✅
37. Fundus flavimaculatus is associated with:
A. Stargardt’s disease
B. Retinitis pigmentosa
C. Diabetic retinopathy
D. Hypertensive retinopathy
View Answer
A. Stargardt’s disease ✅ Exp: Lipofuscin accumulation in Stargardt’s disease.
38. Loss of central vision with preserved peripheral vision occurs in:
A. Age-related macular degeneration
B. Glaucoma
C. Retinitis pigmentosa
D. Optic atrophy
View Answer
A. Age-related macular degeneration ✅ Exp: Macula → central loss.
39. Peripheral visual field loss with preserved central vision occurs in:
A. Glaucoma
B. Macular degeneration
C. Optic neuritis
D. Central serous retinopathy
View Answer
A. Glaucoma ✅ Exp: Glaucoma affects periphery first.
40. Retinitis pigmentosa classically shows:
A. Bone spicule pigmentation
B. Cherry red spot
C. Flame hemorrhages
D. Cotton wool spots
View Answer
A. Bone spicule pigmentation ✅ Exp: RP → pigment migration → bone spicule pattern.
