ABO Ocular Anatomy & Physiology 2 — Questions and Answers
Question 1: Which layer of the cornea is responsible for maintaining corneal hydration through its pump function?
- Bowman's layer
- Descemet's membrane
- Corneal endothelium (Correct answer)
- Stroma
Correct answer: Corneal endothelium
The corneal endothelium uses Na+/K+-ATPase pumps to actively remove fluid from the stroma, maintaining corneal clarity.
Question 2: The fovea centralis has the highest visual acuity because it contains predominantly which cell type?
- Rod photoreceptors
- Müller cells
- Cone photoreceptors (Correct answer)
- Retinal ganglion cells
Correct answer: Cone photoreceptors
The fovea centralis is packed with cone photoreceptors and lacks rods, enabling maximum visual acuity and color discrimination.
Question 3: Which structure forms the boundary between the anterior and posterior chambers of the eye?
- Cornea
- Trabecular meshwork
- Iris (Correct answer)
- Zonular fibers
Correct answer: Iris
The iris separates the anterior chamber (between cornea and iris) from the posterior chamber (between iris and lens).
Question 4: The optic nerve head receives its blood supply primarily from which arterial source?
- Central retinal artery
- Short posterior ciliary arteries (Correct answer)
- Long posterior ciliary arteries
- Anterior ciliary arteries
Correct answer: Short posterior ciliary arteries
The prelaminar and laminar portions of the optic nerve head are supplied mainly by branches of the short posterior ciliary arteries.
Question 5: What is the primary function of the ciliary body's pars plana?
- Aqueous humor production
- Lens accommodation
- Vitreous attachment point and surgical access site (Correct answer)
- Drainage of aqueous humor
Correct answer: Vitreous attachment point and surgical access site
The pars plana is a relatively avascular, flat region that serves as a safe surgical access site and anchors the vitreous base.
Question 6: The ganglion cells of the retina send their axons through which structure to reach the lateral geniculate nucleus?
- Optic chiasm only
- Optic tract only
- Optic nerve, optic chiasm, and optic tract (Correct answer)
- Superior colliculus directly
Correct answer: Optic nerve, optic chiasm, and optic tract
Retinal ganglion cell axons travel through the optic nerve, partially decussate at the optic chiasm, and continue as the optic tract to the LGN.
Question 7: Which muscle is responsible for elevating the upper eyelid and is innervated by cranial nerve III?
- Orbicularis oculi
- Levator palpebrae superioris (Correct answer)
- Superior tarsal muscle (Müller's muscle)
- Frontalis muscle
Correct answer: Levator palpebrae superioris
The levator palpebrae superioris is the primary elevator of the upper eyelid and is innervated by the superior division of CN III.
ABO Ocular Anatomy & Physiology 2
Which layer of the cornea is responsible for maintaining corneal hydration through its pump function?