Master the Physiology of Eye and Vision mcq with 40 expertly crafted MCQs covering Corneal transparency, Aqueous humor secretion, drainage pathways, and Intraocular Pressure (IOP). Perfect for ophthalmology students and NEET PG aspirants — learn key concepts like corneal layers, endothelial pump, aqueous outflow, tonometry, and ocular hypertension in one comprehensive quiz guide. go to our index page to opththalmology and optometry mcq
Corneal Transparency & Physiology
1. The main reason for corneal transparency is:
A. High water content
B. Regular arrangement of collagen fibrils
C. Absence of blood vessels
D. Thin epithelium
View Answer
B. Regular arrangement of collagen fibrils ✅ Exp: Corneal transparency depends on the uniform spacing of collagen fibres in stroma (Maurice’s lattice theory).
2. Normal corneal hydration is maintained at:
A. 100%
B. 78%
C. 50%
D. 90%
View Answer
B. 78% ✅ Exp: Cornea stays relatively dehydrated (~78% water) for transparency.
3. Which corneal layer is responsible for maintaining dehydration?
A. Epithelium
B. Endothelium
C. Bowman’s membrane
D. Stroma
View Answer
B. Endothelium ✅ Exp: Endothelial pump (Na+/K+ ATPase) regulates stromal hydration.
4. The main ion transported by corneal endothelial pump is:
A. Sodium
B. Potassium
C. Chloride
D. Calcium
View Answer
A. Sodium ✅ Exp: Active Na+ transport drives fluid out of stroma.
5. The corneal epithelium contributes to transparency by:
A. Tight junctions preventing fluid entry
B. Producing aqueous humor
C. Secreting collagen
D. Forming trabecular meshwork
View Answer
A. Tight junctions preventing fluid entry ✅ Exp: Epithelial barrier stops excess fluid absorption.
6. Most oxygen to cornea is supplied from:
A. Aqueous humor
B. Tear film
C. Conjunctival vessels
D. Limbal vessels
View Answer
B. Tear film ✅ Exp: Oxygen diffuses from atmosphere via tears.
7. During sleep, corneal oxygen is mainly derived from:
A. Palpebral conjunctiva
B. Palpebral vessels
C. Tear film
D. Limbal capillaries
View Answer
B. Palpebral vessels ✅ Exp: Closed eye → oxygen from palpebral conjunctival vessels.
8. Corneal nutrition (glucose) comes primarily from:
A. Tear film
B. Aqueous humor
C. Limbal vessels
D. Conjunctiva
View Answer
B. Aqueous humor ✅ Exp: Glucose diffuses from aqueous humor.
9. Normal corneal thickness (central) is about:
A. 250 µm
B. 500–550 µm
C. 700 µm
D. 1000 µm
View Answer
B. 500–550 µm ✅ Exp: Central cornea ~520 µm, periphery thicker.
10. Which corneal layer is non-regenerating?
A. Epithelium
B. Stroma
C. Bowman’s membrane
D. Endothelium
View Answer
C. Bowman’s membrane ✅ Exp: Bowman’s does not regenerate after injury.
Aqueous Humor Formation & Drainage
11. Aqueous humor is formed mainly by:
A. Simple diffusion
B. Ultrafiltration
C. Active secretion
D. Osmosis
View Answer
C. Active secretion ✅ Exp: 70% secretion by ciliary epithelium; rest diffusion & ultrafiltration.
12. Aqueous humor is secreted by:
A. Non-pigmented ciliary epithelium
B. Pigmented ciliary epithelium
C. Iris stroma
D. Lens epithelium
View Answer
A. Non-pigmented ciliary epithelium ✅ Exp: Non-pigmented layer actively secretes aqueous.
13. Normal aqueous humor production rate is:
A. 1 µl/min
B. 2–3 µl/min
C. 5 µl/min
D. 0.5 µl/min
View Answer
B. 2–3 µl/min ✅ Exp: Average rate ~2.5 µl/min.
14. Aqueous humor flow direction is:
A. Posterior → Anterior chamber → Trabecular meshwork
B. Anterior → Posterior chamber
C. Posterior → Vitreous
D. Anterior → Retina
View Answer
A. Posterior → Anterior chamber → Trabecular meshwork ✅ Exp: Formed in posterior chamber → anterior chamber → outflow.
15. Major pathway of aqueous drainage:
A. Uveoscleral outflow
B. Trabecular (conventional) pathway
C. Episcleral vessels only
D. Retinal veins
View Answer
B. Trabecular (conventional) pathway ✅ Exp: 85–90% via trabecular meshwork → Schlemm’s canal.
16. Percentage of aqueous humor drained via uveoscleral pathway:
A. 10–15%
B. 50%
C. 90%
D. 2%
View Answer
A. 10–15% ✅ Exp: Minor pathway, important for prostaglandin drugs.
17. Aqueous humor contains the highest concentration of:
A. Protein
B. Ascorbate (vitamin C)
C. Sodium
D. Albumin
View Answer
B. Ascorbate (vitamin C) ✅ Exp: Aqueous has 20× higher vitamin C than plasma.
18. Aqueous humor has very low:
A. Protein content
B. Ascorbate
C. Lactate
D. Sodium
View Answer
A. Protein content ✅ Exp: Protein is <1% of plasma → maintains transparency.
19. Aqueous humor turnover time is approximately:
A. 30 minutes
B. 90 minutes
C. 12 hours
D. 1 day
View Answer
B. 90 minutes ✅ Exp: Complete turnover ~100 minutes.
20. Circadian rhythm of aqueous secretion shows:
A. Higher at night
B. Higher during day
C. Constant
D. Random
View Answer
B. Higher during day ✅ Exp: Production highest in morning, least at night.
21. Normal IOP range is:
A. 5–15 mmHg
B. 10–21 mmHg
C. 15–30 mmHg
D. 20–25 mmHg
View Answer
B. 10–21 mmHg ✅ Exp: Normal range = 10–21 mmHg (mean ~16).
22. Goldmann applanation tonometry is based on:
A. Indentation principle
B. Imbert-Fick law
C. Rebound principle
D. Fluorescence
View Answer
B. Imbert-Fick law ✅ Exp: Measures pressure by flattening corneal surface.
23. IOP is lowest:
A. Early morning
B. Afternoon
C. Evening
D. Night
View Answer
B. Afternoon ✅ Exp: Peaks in early morning; lowest in afternoon.
24. Valsalva maneuver causes:
A. IOP increase
B. IOP decrease
C. No effect
D. IOP fluctuation only at night
View Answer
A. IOP increase ✅ Exp: Increased venous pressure → ↑ IOP.
25. Normal diurnal variation of IOP is:
A. 0–2 mmHg
B. 2–6 mmHg
C. 8–10 mmHg
D. 10–15 mmHg
View Answer
B. 2–6 mmHg ✅ Exp: Normal variation within 6 mmHg.
26. IOP increases in:
A. Supine position
B. Upright position
C. After general anesthesia
D. Hypotension
View Answer
A. Supine position ✅ Exp: Venous congestion in supine raises IOP.
27. Aqueous outflow resistance is greatest at:
A. Trabecular meshwork
B. Schlemm’s canal
C. Episcleral veins
D. Uveoscleral pathway
View Answer
A. Trabecular meshwork ✅ Exp: Main site of resistance in trabecular meshwork.
28. Normal episcleral venous pressure is:
A. 5 mmHg
B. 10 mmHg
C. 15 mmHg
D. 20 mmHg
View Answer
A. 5 mmHg ✅
29. Drugs that increase uveoscleral outflow:
A. Beta-blockers
B. Prostaglandin analogues
C. Carbonic anhydrase inhibitors
D. Alpha-agonists
View Answer
B. Prostaglandin analogues ✅ Exp: PG analogues increase unconventional outflow.
30. Carbonic anhydrase inhibitors reduce IOP by:
A. Increasing outflow
B. Decreasing aqueous secretion
C. Increasing EVP
D. Enhancing corneal pump
View Answer
B. Decreasing aqueous secretion ✅ Exp: Inhibit bicarbonate formation → less secretion.
31. Most accurate tonometry method is:
A. Schiotz tonometer
B. Goldmann applanation
C. Air puff tonometer
D. Perkins tonometer
View Answer
B. Goldmann applanation ✅ Exp: Goldmann = gold standard.
32. Ocular hypertension is defined as:
A. IOP > 18 mmHg
B. IOP > 21 mmHg with normal optic disc & fields
C. Raised IOP with glaucoma
D. IOP < 10 mmHg
View Answer
B. IOP > 21 mmHg with normal optic disc & fields ✅ Exp: High pressure without glaucomatous damage.
33. Hypotony is defined as IOP:
A. <10 mmHg
B. <6 mmHg
C. <15 mmHg
D. <20 mmHg
View Answer
B. <6 mmHg ✅ Exp: Low IOP (<6 mmHg) can cause retinal folds & edema.
34. Steroids cause glaucoma mainly by:
A. Increasing aqueous production
B. Decreasing trabecular outflow
C. Increasing episcleral pressure
D. Increasing uveoscleral flow
View Answer
B. Decreasing trabecular outflow ✅ Exp: Steroids alter TM cells, reducing outflow.
35. Which factor reduces IOP?
A. Exercise
B. Supine posture
C. Valsalva
D. Steroids
View Answer
A. Exercise ✅ Exp: Exercise transiently lowers IOP.
36. Which systemic drug reduces IOP?
A. Acetazolamide
B. Atropine
C. Steroids
D. Epinephrine
View Answer
A. Acetazolamide ✅ Exp: Carbonic anhydrase inhibitor.
37. Which drug can cause transient rise in IOP?
A. Mydriatics (e.g., atropine)
B. Beta-blockers
C. Prostaglandins
D. CAIs
View Answer
A. Mydriatics (e.g., atropine) ✅ Exp: Pupil dilation may block angle in narrow angles.
38. Tonography measures:
A. Aqueous outflow facility
B. Aqueous secretion
C. Retinal circulation
D. Corneal hydration
View Answer
A. Aqueous outflow facility ✅ Exp: Assesses facility of outflow.
39. Normal aqueous humor turnover per day:
A. 1–2 times
B. 12–13 times
C. 20 times
D. 3–4 times
View Answer
B. 12–13 times ✅ Exp: With ~100 min turnover → ~12/day.
40. IOP rises transiently after:
A. Coughing, sneezing, straining
B. Sleep
C. Exercise
D. Hyperventilation
View Answer
A. Coughing, sneezing, straining ✅ Exp: All Valsalva-like maneuvers transiently increase IOP.
