ABO NOCE Basic Opticianry Ocular Anatomy and Conditions Questions and Answers 4 — Questions and Answers
Question 1: Which cells in the retina are responsible for contrast detection and are activated by differences in illumination across adjacent areas?
- Rods
- Amacrine cells
- Horizontal cells (Correct answer)
- Ganglion cells
Correct answer: Horizontal cells
Horizontal cells laterally connect photoreceptors and bipolar cells, enabling contrast enhancement through lateral inhibition.
Question 2: A patient presents with loss of the temporal visual field in both eyes. The lesion most likely involves the:
- Left optic nerve
- Optic chiasm (Correct answer)
- Left optic tract
- Right occipital cortex
Correct answer: Optic chiasm
Bitemporal hemianopia is the classic presentation of an optic chiasm lesion affecting the crossing nasal fibers from both eyes.
Question 3: Keratoconus is best described as:
- Inflammation of the corneal stroma
- Progressive thinning and conical protrusion of the cornea (Correct answer)
- Accumulation of lipid in the peripheral cornea
- Calcium deposits in Bowman's layer
Correct answer: Progressive thinning and conical protrusion of the cornea
Keratoconus is a degenerative disorder causing progressive corneal thinning and conical ectasia, leading to irregular astigmatism.
Question 4: The space between the cornea and iris is referred to as the:
- Posterior chamber
- Vitreous chamber
- Anterior chamber (Correct answer)
- Perilimbal space
Correct answer: Anterior chamber
The anterior chamber lies between the posterior corneal surface and the anterior iris/lens surface and is filled with aqueous humor.
Question 5: Which condition causes cobblestone papillae under the upper eyelid and is linked to allergen exposure?
- Bacterial conjunctivitis
- Vernal keratoconjunctivitis (Correct answer)
- Pinguecula
- Blepharitis
Correct answer: Vernal keratoconjunctivitis
Vernal keratoconjunctivitis is a severe allergic condition featuring giant cobblestone papillae on the tarsal conjunctiva.
Question 6: Night blindness (nyctalopia) is most commonly associated with deficiency of which vitamin?
- Vitamin C
- Vitamin D
- Vitamin A (Correct answer)
- Vitamin B12
Correct answer: Vitamin A
Vitamin A is essential for the synthesis of rhodopsin in rod photoreceptors; its deficiency impairs dark adaptation and causes night blindness.
Question 7: The Schlemm's canal drains aqueous humor into which vascular system?
- Central retinal vein
- Episcleral veins (Correct answer)
- Vorticose veins
- Choroidal capillaries
Correct answer: Episcleral veins
Aqueous exits the trabecular meshwork into Schlemm's canal, then drains into episcleral venous collectors.
ABO NOCE Basic Opticianry Ocular Anatomy and Conditions Questions and Answers 4
Which cells in the retina are responsible for contrast detection and are activated by differences in illumination across adjacent areas?