November 17, 2010

USMLE 1 Question 22

Which of the following is true of the optic disc?

a) no arteries pass through it
b) no veins pass through it
c) it appears dark red on fundoscopy
d) contains a concentration of photoreceptors
e) it is normally less than 1cm in diameter

The correct answer is E


This is the point at which axons leave the eyeball and join the optic nerve. Also, arteries enter and veins leave the retina at the optic disk. There are no photoreceptors here, hence it is known as the 'blind spot'. It is a pinky-yellow oval, approximately 2mm in diameter, and situated in the nasal retina

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