ABO NOCE Basic Opticianry Ocular Anatomy and Physiology 5 — Questions and Answers
Question 1: The retinal pigment epithelium (RPE) is located between which two structures?
- Ganglion cells and bipolar cells
- Photoreceptors and choroid (Correct answer)
- Inner and outer plexiform layers
- Vitreous and inner limiting membrane
Correct answer: Photoreceptors and choroid
The RPE is a single layer of pigmented cells located between the photoreceptor outer segments and the choroidal vasculature (Bruch's membrane).
Question 2: Which structure is responsible for draining aqueous humor from the eye?
- Schlemm's canal (Correct answer)
- Hyaloid canal
- Cloquet's canal
- Petit's canal
Correct answer: Schlemm's canal
Schlemm's canal (the scleral venous sinus) collects aqueous humor from the trabecular meshwork and drains it into the episcleral veins.
Question 3: What percentage of the eye's total refractive power is provided by the cornea?
- 33%
- 50%
- 67% (Correct answer)
- 80%
Correct answer: 67%
The cornea provides approximately two-thirds (about 43 of the total ~60 diopters, or ~67%) of the eye's total refractive power.
Question 4: Which extraocular muscle is innervated by cranial nerve IV (trochlear nerve)?
- Inferior oblique
- Superior rectus
- Superior oblique (Correct answer)
- Lateral rectus
Correct answer: Superior oblique
The trochlear nerve (CN IV) innervates only the superior oblique muscle, which depresses and intorts the eye.
Question 5: The angle of the anterior chamber is formed by the junction of the:
- Cornea and lens
- Iris and cornea (Correct answer)
- Sclera and retina
- Choroid and iris
Correct answer: Iris and cornea
The iridocorneal angle (anterior chamber angle) is formed where the peripheral iris meets the posterior cornea, and it contains the trabecular meshwork.
Question 6: Which type of collagen is the primary structural component of the corneal stroma?
- Type I collagen (Correct answer)
- Type II collagen
- Type III collagen
- Type IV collagen
Correct answer: Type I collagen
Type I collagen is the predominant collagen type in the corneal stroma, arranged in regularly spaced lamellae to maintain corneal transparency.
Question 7: Accommodation is the ability of the eye to change focus. Which structure changes shape during accommodation?
- Cornea
- Iris
- Crystalline lens (Correct answer)
- Vitreous
Correct answer: Crystalline lens
The crystalline lens changes its curvature (becomes more convex) during accommodation to increase the eye's refractive power for near vision.
ABO NOCE Basic Opticianry Ocular Anatomy and Physiology 5
The retinal pigment epithelium (RPE) is located between which two structures?