ABO NOCE Basic Opticianry Ocular Anatomy and Physiology 4 — Questions and Answers
Question 1: The corneal endothelium pumps fluid out of the cornea to maintain its transparency. This process requires which ion?
- Calcium
- Potassium
- Sodium (Correct answer)
- Chloride
Correct answer: Sodium
The corneal endothelium uses Na+/K+-ATPase pumps driven by sodium ions to actively transport fluid out of the corneal stroma.
Question 2: Which part of the optic nerve is visible during fundoscopic examination?
- Intraorbital portion
- Intracanalicular portion
- Optic disc (Correct answer)
- Optic chiasm
Correct answer: Optic disc
The optic disc (optic nerve head) is the only part of the optic nerve visible during fundoscopy; it appears as a pale oval disc on the retina.
Question 3: Which type of photoreceptor is most sensitive to low-light (scotopic) conditions?
- Cones
- Rods (Correct answer)
- Bipolar cells
- Ganglion cells
Correct answer: Rods
Rods are highly sensitive photoreceptors that function in dim light (scotopic vision) and are responsible for peripheral and night vision.
Question 4: The zonules of Zinn connect the lens to which structure?
- Cornea
- Iris
- Ciliary body (Correct answer)
- Vitreous
Correct answer: Ciliary body
The zonular fibers (zonules of Zinn) suspend the crystalline lens by connecting it to the ciliary body.
Question 5: Where does the optic chiasm receive its blood supply primarily from?
- Ophthalmic artery
- Central retinal artery
- Internal carotid artery (Correct answer)
- Middle cerebral artery
Correct answer: Internal carotid artery
The optic chiasm is supplied primarily by branches of the internal carotid artery, including the anterior cerebral and anterior communicating arteries.
Question 6: Which layer of the retina contains the cell bodies of bipolar neurons?
- Outer nuclear layer
- Inner nuclear layer (Correct answer)
- Ganglion cell layer
- Nerve fiber layer
Correct answer: Inner nuclear layer
The inner nuclear layer contains the cell bodies of bipolar cells, horizontal cells, amacrine cells, and Müller cells.
Question 7: What is the refractive index of the cornea?
- 1.33
- 1.376 (Correct answer)
- 1.42
- 1.50
Correct answer: 1.376
The refractive index of the corneal stroma is approximately 1.376, which contributes to its total refractive power of about +43 diopters.
ABO NOCE Basic Opticianry Ocular Anatomy and Physiology 4
The corneal endothelium pumps fluid out of the cornea to maintain its transparency.
This process requires which ion?