Deepen your knowledge Physiology of eye mcq next 40 advanced MCQs on Corneal transparency, Aqueous humor secretion, and Intraocular Pressure (IOP). Learn about endothelial pump function, corneal edema, tonometry, prostaglandin action, trabecular outflow, and glaucoma management. Ideal for ophthalmology students, NEET PG, AIIMS, and medical exam preparation. visit our ophthalmolgy mcq for opthalmic officers exams
Corneal Physiology
41. The primary source of corneal ATP is:
A. Anaerobic glycolysis
B. Oxidative phosphorylation
C. Pentose phosphate pathway
D. Citric acid cycle
View Answer
A. Anaerobic glycolysis ✅ Exp: The avascular cornea derives 85% of energy from anaerobic glycolysis.
42. Endothelial cell density at birth is:
A. 2500–3000 cells/mm²
B. 1000 cells/mm²
C. 4000–5000 cells/mm²
D. <1500 cells/mm²
View Answer
A. 2500–3000 cells/mm² ✅ Exp: Normal density declines with age; <1000/mm² risks edema.
43. The main antioxidant in cornea protecting from UV damage:
A. Vitamin A
B. Vitamin C (ascorbate)
C. Glutathione
D. Catalase
View Answer
B. Vitamin C (ascorbate) ✅ Exp: Ascorbate in aqueous and cornea absorbs UV rays.
44. Corneal edema develops when endothelial cells fall below:
A. 2500/mm²
B. 1500/mm²
C. 500/mm²
D. 2000/mm²
View Answer
C. 500/mm² ✅ Exp: Critical threshold for pump failure.
45. The corneal deturgescence (relative dehydration) is maintained by:
A. Endothelial Na+/K+ pump
B. Osmotic gradient only
C. Lacrimal drainage
D. Limbal vessels
View Answer
A. Endothelial Na+/K+ pump ✅ Exp: Endothelial pumps remove water from stroma.
46. Most common cause of corneal hypoxia is:
A. Contact lens wear
B. Vitamin A deficiency
C. Trauma
D. Sleep
View Answer
A. Contact lens wear ✅ Exp: Contact lenses reduce oxygen diffusion.
47. Which corneal layer contributes most to rigidity?
A. Stroma
B. Epithelium
C. Endothelium
D. Descemet’s membrane
View Answer
A. Stroma ✅ Exp: Stroma forms ~90% of thickness, providing tensile strength.
48. Corneal swelling first affects:
A. Epithelium
B. Posterior stroma
C. Anterior stroma
D. Descemet’s membrane
View Answer
B. Posterior stroma ✅ Exp: Swelling begins in posterior stroma where lamellae are loose.
49. Corneal deturgescence failure causes:
A. Hydrops
B. Coloboma
C. Microcornea
D. Glaucoma
View Answer
A. Hydrops ✅ Exp: Endothelial decompensation → corneal edema/hydrops.
50. Lattice theory of corneal transparency was proposed by:
A. Maurice
B. Goldman
C. Vogt
D. Duke-Elder
View Answer
A. Maurice ✅ Exp: Maurice explained uniform fibril spacing → transparency.
Aqueous Humor Physiology of eye mcq
51. Enzyme critical for aqueous secretion:
A. Carbonic anhydrase
B. Aldolase
C. ATPase
D. Glucose-6-phosphatase
View Answer
A. Carbonic anhydrase ✅ Exp: Produces bicarbonate, drives ion transport.
52. Which drug inhibits aqueous humor formation?
A. Acetazolamide
B. Pilocarpine
C. Prostaglandin analogues
D. Timolol
View Answer
A. Acetazolamide ✅ Exp: Acetazolamide inhibits carbonic anhydrase.
53. Hyperosmotic agents reduce IOP by:
A. Drawing fluid from vitreous
B. Blocking trabecular meshwork
C. Inhibiting aqueous secretion directly
D. Enhancing uveoscleral outflow
View Answer
A. Drawing fluid from vitreous ✅ Exp: They increase plasma osmolality → dehydrate vitreous.
54. Aqueous humor turnover occurs approximately every:
A. 1–2 hours
B. 6 hours
C. 12 hours
D. 24 hours
View Answer
A. 1–2 hours ✅ Exp: Turnover ~100 minutes.
55. Protein content of aqueous compared to plasma is:
A. Similar
B. 1/10
C. 1/20–1/30
D. Higher
View Answer
C. 1/20–1/30 ✅ Exp: Very low protein maintains clarity.
56. Main nutrient in aqueous for lens metabolism:
A. Glucose
B. Vitamin A
C. Protein
D. Lactate
View Answer
A. Glucose ✅ Exp: Lens gets glucose from aqueous humor.
57. Which prostaglandin analogue increases uveoscleral outflow?
A. Latanoprost
B. Timolol
C. Acetazolamide
D. Pilocarpine
View Answer
A. Latanoprost ✅ Exp: Latanoprost → ↑ uveoscleral outflow.
58. Adrenergic agonists (α2, e.g., brimonidine) reduce IOP by:
A. Decreasing aqueous formation
B. Blocking Schlemm’s canal
C. Increasing lens transparency
D. Inhibiting corneal epithelium
View Answer
A. Decreasing aqueous formation ✅ Exp: Reduce secretion + modestly ↑ uveoscleral outflow.
59. Pilocarpine reduces IOP by:
A. Opening trabecular meshwork via ciliary muscle contraction
B. Decreasing aqueous formation
C. Increasing episcleral venous pressure
D. Blocking uveoscleral flow
View Answer
A. Opening trabecular meshwork via ciliary muscle contraction ✅ Exp: Parasympathomimetic → improves conventional outflow.
60. Beta-blockers (e.g., timolol) lower IOP by:
A. Decreasing aqueous humor production
B. Increasing trabecular outflow
C. Increasing episcleral venous pressure
D. Reducing vitreous volume
View Answer
A. Decreasing aqueous humor production ✅ Exp: Reduce secretion at ciliary epithelium.
Intraocular Pressure
61. Normal mean IOP in adults:
A. 10 mmHg
B. 16 mmHg
C. 20 mmHg
D. 22 mmHg
View Answer
B. 16 mmHg ✅ Exp: Mean ~16 mmHg, range 10–21.
62. IOP is highest:
A. Early morning
B. Afternoon
C. Evening
D. Night
View Answer
A. Early morning ✅ Exp: Peak at 6–8 am.
63. IOP decreases with:
A. Alcohol intake
B. Supine posture
C. Valsalva
D. Mydriatics
View Answer
A. Alcohol intake ✅ Exp: Alcohol transiently lowers IOP.
64. IOP increases in:
A. Supine posture
B. Exercise
C. Hyperventilation
D. Alcohol
View Answer
A. Supine posture ✅ Exp: Supine → venous congestion.
65. Which factor has least effect on IOP?
A. Age
B. Sex
C. Circadian rhythm
D. Posture
View Answer
B. Sex ✅ Exp: Sex has minimal influence.
66. Thin cornea in tonometry causes:
A. Underestimation of IOP
B. Overestimation
C. No effect
D. Random error
View Answer
A. Underestimation of IOP ✅ Exp: Thin corneas → falsely low IOP.
67. Thick cornea in tonometry causes:
A. Overestimation of IOP
B. Underestimation
C. No effect
D. Hypotony
View Answer
A. Overestimation of IOP ✅ Exp: Opposite effect to thin cornea.
68. Manometric method measures IOP by:
A. Direct cannulation of anterior chamber
B. Applanation
C. Indentation
D. Non-contact
View Answer
A. Direct cannulation of anterior chamber ✅ Exp: Gold standard but invasive.
69. Rebound tonometry (iCare) is useful in:
A. Children
B. Only adults
C. Aniridia
D. Coloboma
View Answer
A. Children ✅ Exp: Handheld, no anesthesia required → pediatric use.
70. Dynamic contour tonometry is less affected by:
A. Corneal thickness
B. IOP fluctuation
C. Aqueous secretion
D. Outflow resistance
View Answer
A. Corneal thickness ✅ Exp: Measures true IOP independent of corneal rigidity.
71. The most common cause of secondary raised EVP is:
A. Carotid-cavernous fistula
B. Diabetes
C. Hypertension
D. Retinitis pigmentosa
View Answer
A. Carotid-cavernous fistula ✅ Exp: Arteriovenous shunt → ↑ episcleral pressure.
72. In which condition is aqueous production reduced?
A. Uveitis
B. Angle-closure glaucoma
C. Ocular hypertension
D. Steroid use
View Answer
A. Uveitis ✅ Exp: Inflammation damages ciliary body → ↓ secretion.
73. Drugs increasing aqueous production:
A. Epinephrine
B. Acetazolamide
C. Timolol
D. Pilocarpine
View Answer
A. Epinephrine ✅ Exp: Adrenergics stimulate ciliary body.
74. The facility of outflow is measured in:
A. µl/min/mmHg
B. µl/sec
C. mmHg
D. µl/hr
View Answer
A. µl/min/mmHg ✅ Exp: Expressed as volume/time/pressure.
75. Uveoscleral outflow increases with:
A. Prostaglandins
B. Steroids
C. Beta-blockers
D. Mydriatics
View Answer
A. Prostaglandins ✅ Exp: PG analogues enhance unconventional pathway.
76. Laser trabeculoplasty lowers IOP by:
A. Remodeling trabecular meshwork
B. Decreasing aqueous production
C. Increasing episcleral pressure
D. Increasing vitreous drainage
View Answer
A. Remodeling trabecular meshwork ✅ Exp: Improves trabecular outflow.
77. Aqueous misdirection (malignant glaucoma) is due to:
A. Posterior misdirection of aqueous
B. Overproduction
C. Trabecular blockage
D. Uveitis
View Answer
A. Posterior misdirection of aqueous ✅ Exp: Fluid trapped behind vitreous.
78. Normal aqueous humor pH is:
A. 7.2
B. 6.8
C. 7.5
D. 7.8
View Answer
A. 7.2 ✅ Exp: Slightly alkaline relative to plasma.
79. After cataract surgery, IOP transiently rises due to:
A. Retained viscoelastic material
B. Decreased trabecular outflow
C. Increased aqueous secretion
D. Increased EVP
View Answer
A. Retained viscoelastic material ✅ Exp: OVD remnants block meshwork temporarily.
80. The main site of resistance to aqueous outflow:
A. Juxtacanalicular trabecular meshwork
B. Schlemm’s canal
C. Episcleral veins
D. Iris root
View Answer
A. Juxtacanalicular trabecular meshwork ✅ Exp: JCT is key site of resistance.
