JCAHPO Ocular Anatomy & Physiology 2 — Questions and Answers
Question 1: Which photoreceptors are primarily responsible for color vision and function best under photopic (bright light) conditions?
- Rods
- Cones (Correct answer)
- Horizontal cells
- Amacrine cells
Correct answer: Cones
Cones are concentrated in the macula, contain three types of opsins for color discrimination, and are optimized for bright-light and high-acuity vision.
Question 2: The crystalline lens receives its nutrition primarily from which source?
- Central retinal artery
- Aqueous humor and vitreous humor (Correct answer)
- Choroidal blood supply
- Ciliary arteries
Correct answer: Aqueous humor and vitreous humor
The avascular crystalline lens is nourished entirely by diffusion of nutrients from the aqueous humor anteriorly and vitreous humor posteriorly.
Question 3: Which layer of the eye is known as the 'uveal tract' and consists of the iris, ciliary body, and choroid?
- Outer fibrous tunic
- Middle vascular tunic (Correct answer)
- Inner neural tunic
- Anterior segment
Correct answer: Middle vascular tunic
The uveal tract is the middle vascular tunic of the eye, comprising the iris, ciliary body, and choroid, providing blood supply to surrounding ocular structures.
Question 4: At the optic chiasm, fibers from which portion of the retina cross to the contralateral optic tract?
- Temporal retinal fibers
- Nasal retinal fibers (Correct answer)
- Superior retinal fibers
- Macular fibers only
Correct answer: Nasal retinal fibers
At the optic chiasm, nasal retinal fibers (which carry temporal visual field information) decussate to the contralateral side, while temporal fibers remain ipsilateral.
Question 5: What is the approximate normal range for adult intraocular pressure (IOP)?
- 0–5 mmHg
- 6–10 mmHg
- 10–21 mmHg (Correct answer)
- 22–30 mmHg
Correct answer: 10–21 mmHg
Normal adult IOP is generally considered 10–21 mmHg; pressures consistently above 21 mmHg are a significant risk factor for glaucomatous optic nerve damage.
Question 6: The sphincter pupillae muscle, which constricts the pupil, is innervated by which division of the autonomic nervous system?
- Sympathetic (adrenergic)
- Parasympathetic (cholinergic) (Correct answer)
- Somatic motor
- Sensory trigeminal
Correct answer: Parasympathetic (cholinergic)
The sphincter pupillae is innervated by parasympathetic fibers carried via the oculomotor nerve (CN III) and the short ciliary nerves, causing miosis.
Question 7: The ora serrata marks the boundary between which two structures of the eye?
- Cornea and sclera
- Retina and choroid
- Peripheral retina and pars plana of the ciliary body (Correct answer)
- Vitreous and aqueous
Correct answer: Peripheral retina and pars plana of the ciliary body
The ora serrata is the anterior margin of the neurosensory retina where it meets the pars plana of the ciliary body, approximately 8 mm posterior to the limbus.
JCAHPO Ocular Anatomy & Physiology 2
Which photoreceptors are primarily responsible for color vision and function best under photopic (bright light) conditions?