CPOA Basic Science 3 — Questions and Answers
Question 1: The nasolacrimal duct drains tears into which anatomical location?
- Maxillary sinus
- Inferior meatus of the nasal cavity (Correct answer)
- Middle meatus of the nasal cavity
- Nasopharynx
Correct answer: Inferior meatus of the nasal cavity
The nasolacrimal duct empties tears into the inferior meatus of the nasal cavity, explaining why crying causes nasal congestion.
Question 2: What is the normal intraocular pressure (IOP) range in a healthy adult?
- 5–10 mmHg
- 10–21 mmHg (Correct answer)
- 22–30 mmHg
- 30–40 mmHg
Correct answer: 10–21 mmHg
Normal IOP ranges from 10 to 21 mmHg; pressures consistently above 21 mmHg may indicate ocular hypertension or glaucoma risk.
Question 3: The optic nerve exits the eye through which structure?
- Fovea
- Macula
- Optic disc (Correct answer)
- Ora serrata
Correct answer: Optic disc
The optic disc (optic nerve head) is where the optic nerve fibers exit the globe; it contains no photoreceptors, creating the physiological blind spot.
Question 4: Which layer of the tear film is produced by the meibomian glands?
- Aqueous layer
- Mucin layer
- Lipid layer (Correct answer)
- Fibrin layer
Correct answer: Lipid layer
The meibomian (tarsal) glands secrete the outermost lipid layer of the tear film, which reduces evaporation of the aqueous layer.
Question 5: Snellen visual acuity of 20/40 means the patient can see at 20 feet what a person with normal vision can see at:
- 10 feet
- 20 feet
- 40 feet (Correct answer)
- 80 feet
Correct answer: 40 feet
20/40 means the patient must be at 20 feet to see what a normally sighted person can see at 40 feet, indicating reduced acuity.
Question 6: The iris contains which type of muscle responsible for pupil dilation?
- Sphincter pupillae (circular muscle)
- Dilator pupillae (radial muscle) (Correct answer)
- Ciliary muscle
- Orbicularis oculi
Correct answer: Dilator pupillae (radial muscle)
The dilator pupillae muscle runs radially in the iris and is innervated by the sympathetic nervous system to enlarge the pupil.
Question 7: What is the primary function of the retinal pigment epithelium (RPE)?
- Producing vitreous humor
- Supporting and nourishing photoreceptors (Correct answer)
- Generating electrical signals
- Refracting incoming light
Correct answer: Supporting and nourishing photoreceptors
The RPE supports the adjacent photoreceptors by recycling visual pigments, absorbing stray light, and transporting nutrients from the choroid.
CPOA Basic Science 3
The nasolacrimal duct drains tears into which anatomical location?