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mousie
thanks for this explanation!
+1
krewfoo99
@macrophage95 Lens are an interal part of the refractive power of the eye. Without the lens the image would not be formed on the retina, thus leading to visual loss
+5
qfever
Do anyone know why not choroid?
+1
adong
@qfever, no choroid would also be more detrimental to vision since it supplies blood to the retina
+3
irgunner
That random zanki card with colobomas associated with a failure of the choroid fissure to close messed me up
+13
mnemonicsfordayz
Seems like the key to this question is in what is omitted from the question stem: there is no mention of vision loss. If we assume there is no vision loss, then we can eliminate things associated with visual acuity (weird to think of in 2 week old but whatever): C, D, E, F. Also, by @hayayah 's reasoning, we eliminate E & F. If you reconsider the "asymmetric left pupil" then the only likely answer between A & B is B, Iris because the iris' central opening forms the pupil. I mistakenly put A because I was thinking of the choroid fissure and I read the question incorrectly - but it's a poorly worded question IMO.
+2
mamed
Key here is that it doesn't affect vision- the only thing would be the iris. All others are used in vision. Don't have to know what a coloboma actually is.
+5
azibird
The extra section of that Zanki card specifically says that a coloboma "can be seen in the iris, retina, choroid, or optic disc." Don't you dare talk trash about Zanki!
+3
fatboyslim
Honestly, I didn't understand what they were trying to ask...NBME has some weird wording sometimes
+1
weirdmed51
@azibird ...upvoting @irgunner cos you went crazy there buddy๐
+
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submitted by โhayayah(1212)
Coloboma is an eye abnormality that occurs before birth. They're missing pieces of tissue in structures that form the eye.
Colobomas affecting the iris, which result in a "keyhole" appearance of the pupil, generally do not lead to vision loss.
Colobomas involving the retina result in vision loss in specific parts of the visual field.
Large retinal colobomas or those affecting the optic nerve can cause low vision, which means vision loss that cannot be completely corrected with glasses or contact lenses.