CPOA Basic Science 4 — Questions and Answers
Question 1: Which refractive error is characterized by the eyeball being too long, causing light to focus in front of the retina?
- Hyperopia
- Myopia (Correct answer)
- Astigmatism
- Presbyopia
Correct answer: Myopia
Myopia (nearsightedness) results from an axially elongated globe or overly curved cornea, causing parallel light rays to converge anterior to the retina.
Question 2: The conjunctiva is classified as which type of tissue?
- Stratified squamous epithelium only
- Columnar epithelium with goblet cells (Correct answer)
- Keratinized epithelium
- Simple squamous epithelium
Correct answer: Columnar epithelium with goblet cells
The conjunctiva is composed of non-keratinized stratified columnar epithelium containing goblet cells that secrete the mucin layer of the tear film.
Question 3: Which portion of the autonomic nervous system causes pupillary constriction (miosis)?
- Sympathetic nervous system
- Parasympathetic nervous system (Correct answer)
- Somatic motor system
- Sensory nervous system
Correct answer: Parasympathetic nervous system
The parasympathetic nervous system, via CN III and the ciliary ganglion, innervates the sphincter pupillae to constrict the pupil.
Question 4: The vitreous humor occupies which space within the eye?
- Between the cornea and iris
- Between the iris and lens
- Behind the lens to the retina (Correct answer)
- Between the sclera and choroid
Correct answer: Behind the lens to the retina
The vitreous humor is the gel-like substance that fills the posterior segment of the eye, from the back of the lens to the retina.
Question 5: A patient with 20/20 vision in one eye and 20/200 in the other who best-corrects to 20/20 in the weaker eye most likely has:
- Strabismus only
- Amblyopia (Correct answer)
- Normal binocular vision
- Presbyopia
Correct answer: Amblyopia
Amblyopia (lazy eye) is reduced best-corrected visual acuity in an eye without detectable organic disease; the vision cannot be fully corrected with glasses alone.
Question 6: The sclera is primarily composed of which structural protein?
- Elastin
- Keratin
- Collagen (Correct answer)
- Fibronectin
Correct answer: Collagen
The sclera is made predominantly of dense, irregularly arranged collagen fibers that provide the eye's rigid white outer shell.
Question 7: Which cells in the retina are the final output neurons that send visual signals to the brain via the optic nerve?
- Bipolar cells
- Horizontal cells
- Ganglion cells (Correct answer)
- Amacrine cells
Correct answer: Ganglion cells
Retinal ganglion cells form the innermost retinal layer; their axons converge at the optic disc and travel through the optic nerve to the brain.
CPOA Basic Science 4
Which refractive error is characterized by the eyeball being too long, causing light to focus in front of the retina?