Retina: X-linked juvenile retinoschisis: practice question

A Ophthalmology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Ophthalmology · Retina: X-linked juvenile retinoschisis

Sample item

A 7-year-old boy has poor reading vision and his maternal uncle had similar trouble. The fovea shows a spoke-wheel pattern of cystic spaces, and a small peripheral inferotemporal schisis cavity is seen. What is the expected ERG finding?

AA markedly reduced a-wave with a preserved b-waveBA selectively reduced b-wave with a relatively preserved a-waveCA normal ERG with an abnormal EOGDA completely flat response in all conditions

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. A selectively reduced b-wave with a relatively preserved a-wave

X-linked retinoschisis is caused by RS1 gene mutations that cause splitting of the inner retinal layers. The ERG shows an electronegative pattern in which the b-wave, generated by bipolar cells, is reduced more than the a-wave. The macular spoke-wheel appearance is the clue.

Option by option

A. A markedly reduced a-wave with a preserved b-wave
A reduced a-wave points to a photoreceptor disease such as retinitis pigmentosa.
B. A selectively reduced b-wave with a relatively preserved a-wave (correct)
Correct. A reduced b-wave with a preserved a-wave gives the electronegative ERG of X-linked retinoschisis.
C. A normal ERG with an abnormal EOG
A normal ERG with abnormal EOG is the pattern of Best disease.
D. A completely flat response in all conditions
A flat ERG is seen in advanced rod-cone dystrophy or Leber congenital amaurosis.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is B, A selectively reduced b-wave with a relatively preserved a-wave. X-linked retinoschisis is caused by RS1 gene mutations that cause splitting of the inner retinal layers.

Why is "A markedly reduced a-wave with a preserved b-wave" not the answer?

A reduced a-wave points to a photoreceptor disease such as retinitis pigmentosa.

Why is "A normal ERG with an abnormal EOG" not the answer?

A normal ERG with abnormal EOG is the pattern of Best disease.

Why is "A completely flat response in all conditions" not the answer?

A flat ERG is seen in advanced rod-cone dystrophy or Leber congenital amaurosis.

What concept does this question test?

It tests Retina: X-linked juvenile retinoschisis in Ophthalmology. The ERG shows an electronegative pattern in which the b-wave, generated by bipolar cells, is reduced more than the a-wave. The macular spoke-wheel appearance is the clue.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Retina: X-linked juvenile retinoschisis?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.