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Lights On-Off Test

FIXME

a.k.a. Small field central fusion test

  • This test is useful in the setting of diplopia in the presence of a dragged fovea causing diplopia giving central-peripheral rivalry
  • Use a single white letter on a black monitor about 20/70 in size
  • Must have a very dark room and no light bleeding through an LCD monitor
  • The patient sees diplopia when fixating on the letter with the lights on
  • With the lights off, the diplopia resolves

see De Pool ME. et al. The Dragged-Fovea Diplopia Syndrome: Clinical Characteristics, Diagnosis and Treatment. Ophthalmology 2005;112:1455-1462

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