Structure and function of the eye MCQs With Answer

Structure and function of the eye MCQs With Answer

The structure and function of the eye are fundamental topics for B. Pharm students, linking ocular anatomy, physiology, and pharmacology. This introduction covers the cornea, lens, aqueous and vitreous humors, retina, photoreceptors (rods and cones), macula, optic nerve, and visual pathways, as well as processes like refraction, accommodation, pupillary reflexes, and intraocular pressure regulation. Understanding ocular barriers, drug entry routes, and common therapeutic targets (e.g., muscarinic, beta, prostaglandin, carbonic anhydrase) is essential for rational drug therapy in glaucoma, infections, and inflammatory eye diseases. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary refractive surface of the eye that contributes most to focusing light on the retina?

• Lens
• Cornea
• Vitreous humor
• Aqueous humor

Correct Answer: Cornea

Q2. Which structure changes curvature during accommodation to focus near objects?

• Cornea
• Ciliary muscle and lens
• Sclera
• Choroid

Correct Answer: Ciliary muscle and lens

Q3. Which layer of the retina contains the photoreceptor cells (rods and cones)?

• Ganglion cell layer
• Inner nuclear layer
• Outer nuclear layer
• Nerve fiber layer

Correct Answer: Outer nuclear layer

Q4. Rod photoreceptors are primarily responsible for which function?

• Color vision in bright light
• High-acuity central vision
• Low-light (scotopic) vision
• Stereoscopic depth perception

Correct Answer: Low-light (scotopic) vision

Q5. Which pigment is the photopigment in rods responsible for light absorption?

• Photopsin
• Melanopsin
• Rhodopsin
• Chloropsin

Correct Answer: Rhodopsin

Q6. The fovea centralis is specialized for:

• Peripheral motion detection
• High-acuity color vision
• Production of aqueous humor
• Drainage of vitreous humor

Correct Answer: High-acuity color vision

Q7. Which structure is the blind spot due to absence of photoreceptors?

• Macula lutea
• Optic disc
• Fovea
• Ciliary body

Correct Answer: Optic disc

Q8. Aqueous humor is produced mainly by which ocular structure?

• Corneal endothelium
• Ciliary epithelium
• Retinal pigment epithelium
• Lacrimal gland

Correct Answer: Ciliary epithelium

Q9. The primary route for aqueous humor drainage is through:

• Uveoscleral outflow only
• Trabecular meshwork into Schlemm’s canal
• Posterior chamber into vitreous
• Direct absorption by conjunctiva

Correct Answer: Trabecular meshwork into Schlemm’s canal

Q10. Normal intraocular pressure (IOP) range is approximately:

• 0–5 mm Hg
• 10–21 mm Hg
• 25–40 mm Hg
• 50–60 mm Hg

Correct Answer: 10–21 mm Hg

Q11. Timolol lowers intraocular pressure primarily by which mechanism?

• Increasing uveoscleral outflow
• Decreasing aqueous humor production via beta-blockade
• Inhibiting carbonic anhydrase
• Inducing miosis

Correct Answer: Decreasing aqueous humor production via beta-blockade

Q12. Pilocarpine produces miosis by acting as a:

• Beta-2 agonist
• Muscarinic receptor agonist
• Alpha-1 antagonist
• Carbonic anhydrase inhibitor

Correct Answer: Muscarinic receptor agonist

Q13. Latanoprost reduces IOP by which primary action?

• Decreasing aqueous production
• Blocking muscarinic receptors
• Increasing uveoscleral outflow via prostaglandin analog effect
• Constriction of episcleral veins

Correct Answer: Increasing uveoscleral outflow via prostaglandin analog effect

Q14. Carbonic anhydrase inhibitors (e.g., acetazolamide) decrease IOP by:

• Increasing trabecular outflow
• Reducing aqueous humor formation through bicarbonate reduction
• Contracting the ciliary muscle
• Blocking adrenergic receptors

Correct Answer: Reducing aqueous humor formation through bicarbonate reduction

Q15. Which retinal layer contains ganglion cell bodies whose axons form the optic nerve?

• Outer plexiform layer
• Inner nuclear layer
• Ganglion cell layer
• Photoreceptor layer

Correct Answer: Ganglion cell layer

Q16. In the pupillary light reflex, the afferent limb is mediated by:

• Oculomotor nerve (III)
• Optic nerve (II)
• Trochlear nerve (IV)
• Facial nerve (VII)

Correct Answer: Optic nerve (II)

Q17. The efferent limb of the pupillary light reflex that causes pupillary constriction travels in:

• Optic nerve
• Oculomotor nerve parasympathetic fibers to sphincter pupillae
• Trigeminal nerve
• Sensory fibers of the facial nerve

Correct Answer: Oculomotor nerve parasympathetic fibers to sphincter pupillae

Q18. Which statement about the blood supply of the retina is true?

• The inner retina is supplied mainly by the choroidal circulation
• The outer retina (photoreceptors) is supplied by the choroid
• The optic disc receives no blood supply
• The retina has no autoregulation

Correct Answer: The outer retina (photoreceptors) is supplied by the choroid

Q19. Retinal detachment most commonly separates which two layers?

• Retinal pigment epithelium and choroid
• Neural retina and retinal pigment epithelium
• Inner limiting membrane and vitreous
• Ganglion cell layer and inner nuclear layer

Correct Answer: Neural retina and retinal pigment epithelium

Q20. Which drug class is contraindicated when mydriasis is undesirable due to risk of precipitating acute angle-closure glaucoma?

• Topical beta-blockers
• Topical prostaglandins
• Systemic anticholinergics and topical mydriatics (e.g., tropicamide)
• Carbonic anhydrase inhibitors

Correct Answer: Systemic anticholinergics and topical mydriatics (e.g., tropicamide)

Q21. Which layer of the eye contains blood vessels that nourish the outer retina and absorbs stray light?

• Sclera
• Choroid
• Corneal stroma
• Conjunctiva

Correct Answer: Choroid

Q22. The aqueous humor flows from the posterior chamber to the anterior chamber through:

• Trabecular meshwork
• Pupil (pupillary aperture)
• Canal of Schlemm
• Vitreous cavity

Correct Answer: Pupil (pupillary aperture)

Q23. Which photoreceptor type has a faster response recovery and is responsible for color discrimination?

• Rods
• Cones
• Bipolar cells
• Horizontal cells

Correct Answer: Cones

Q24. Damage to the optic chiasm typically produces which visual field defect?

• Monocular blindness
• Bitemporal hemianopia
• Quadrantanopia
• Homonymous hemianopia

Correct Answer: Bitemporal hemianopia

Q25. Which ocular barrier most limits systemic drug penetration into the posterior segment (retina) when using topical eye drops?

• Blood-aqueous barrier
• Blood-retinal barrier
• Conjunctival epithelium only
• Lacrimal film

Correct Answer: Blood-retinal barrier

Q26. Which neurotransmitter predominates in the parasympathetic innervation of the eye?

• Norepinephrine
• Dopamine
• Acetylcholine
• Glutamate

Correct Answer: Acetylcholine

Q27. Which optical condition results from an elongated eyeball causing light to focus in front of the retina?

• Hyperopia (farsightedness)
• Emmetropia
• Myopia (nearsightedness)
• Presbyopia

Correct Answer: Myopia (nearsightedness)

Q28. Presbyopia is primarily due to age-related changes in which ocular component?

• Corneal curvature
• Lens elasticity and reduced accommodation
• Retinal photoreceptor loss
• Ciliary nerve degeneration

Correct Answer: Lens elasticity and reduced accommodation

Q29. Which enzyme cascade is directly involved in phototransduction in rods when rhodopsin is activated?

• Adenylyl cyclase → cAMP
• Guanylate cyclase → cGMP increase
• Transducin activation → phosphodiesterase → cGMP hydrolysis
• Protein kinase A activation only

Correct Answer: Transducin activation → phosphodiesterase → cGMP hydrolysis

Q30. A lesion in the right optic tract produces which visual field defect?

• Bitemporal hemianopia
• Left homonymous hemianopia
• Right monocular blindness
• Central scotoma

Correct Answer: Left homonymous hemianopia

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com