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A 12-year-old male of Eastern European descent gave a 10-day history of central blurred vision in the right eye. He was otherwise fit and well but had a history of a "post-viral illness" 1 year ago. There was no recent travel history. He had 6D myopia affecting both eyes and no previous ocular history. On examination, right visual acuity (VA) was 6/36 with spectacles and 6/24 with pinhole. Left VA was 6/5 with spectacles and 6/5 with pinhole. No relative afferent pupillary defect (RAPD) was elicited and anterior segments were white and quiet. Humphrey visual fields and fundus photos are shown above.

1.	Which of the following would be the least informative test?
	d -- Hb electrophoresis This Question of the Week is about 'White dot syndromes'. FFA is of value and the images from this patient are shown below. An ERG may show positive findings in those with birdshot retinopathy (decreased b-wave amplitude) or multiple evanescent white dot syndrome (MEWDS) -- decreased a-wave. The clinical findings could be consistent with syphilis and so treponemal serology would be appropriate, but one may expect to see a vitritis and/or anterior uveitis associated with the retinal findings. Hb electrophoresis would be useful if trying to exclude a haemoglobinopathy, but the clinical picture seen in this case does not fit in with this as a cause. A lumbar puncture may be of value if syphilis (active) or Vogt-Koyanagi-Harada disease was suspected. The retinal findings in this patient could be associated with these conditions. FFA with right eye images - early frame top left then run progresses clockwise - the late staining of lesions can be seen
2.	The differential diagnosis includes:
	e -- all of the above All of these diagnoses should be considered.
3.	Which of the following is/are true?
	f -- (c) and (e) APMPPE lesions tend to resolve spontaneously within 2-3 months, whereas the converse is seen with serpiginous choroidopathy where the prognosis is much worse. We think that this patient is likely to have serpiginous choroidopathy as his vision worsened, and he developed a right RAPD. In addition, the chorioretinal lesions became more extensive. However, the history would have fit better with APMPPE as this tends to affect young adults after a flu-like illness. 90% of cases of birdshot retinopathy are HLA-29 positive. If HLA-29 negative with a similar clinical picture, consider sarcoid as a differential. MEWDS tends to affect young females. Both PIC and multifocal choroiditis may simulate POHS.