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Practice Practice Pointer

Assessment of photopsia (flashing lights)

BMJ 2023; 380 doi: (Published 23 January 2023) Cite this as: BMJ 2023;380:e064767
  1. Jonathan KY Ng, ophthalmology specialist registrar1,
  2. Peiting Joanne Xie, associate consultant2,
  3. Ahmed Saber, GP partner3,
  4. James Huxtable, consultant ophthalmic surgeon4
  1. 1Manchester Royal Eye Hospital, Manchester, UK
  2. 2National Neuroscience Institute, Singapore
  3. 3Church Langley Medical Practice, Harlow, UK
  4. 4Royal Bolton Hospital, Bolton, UK
  1. Correspondence to J Ng{at}

What you need to know

  • If photopsia is monocular, consider an ocular cause; for simultaneous bilateral photopsia, consider neurological or systemic causes

  • Posterior vitreous detachment (manifesting as monocular temporal flashes) is the most common cause of photopsia, and may lead to sight threatening retinal tears and detachment

  • Consider specialist assessment within 24 hours for all suspected ocular causes of acute photopsia

Case 1

A man in his 60s with myopia, who had cataract surgery to his right eye a month earlier, presents with two weeks of intermittent arc-like flashes of light in the right eye. He says the flashes are more prominent in dim conditions. Visual acuity in the right eye is 6/6 unaided.

Dilated fundus examination reveals a retinal tear.He is treated with an immediate laser retinopexy to prevent a retinal detachment.

Case 2

A man in his 60s who smokes daily and has hypertension and diabetes mellitus develops three episodes of visual disturbance over a week. He describes them as sudden light flickering on the right side of both eyes lasting two minutes—with nausea, vertigo, occipital headache, and loss of sensation on his left side. He has been well between episodes and has no deficits on examination.

Magnetic resonance imaging of his brain shows no acute infarct, but shows atherosclerotic mid-basilar and left posterior cerebral artery stenosis and multiple chronic infarcts. He is diagnosed with vertebrobasilar insufficiency and given antiplatelet medication, a statin, and guidance on smoking cessation.

Photopsia is a common presenting symptom in general practice and emergency departments,1 and can be caused by several ocular and systemic conditions, some of which can be threatening to sight or life (box 1). Research specific to photopsia is limited to case series and expert opinion data. The guidance in this article is based on the available evidence and the authors’ clinical experience.

Box 1

Sight threatening and life threatening causes of photopsia

Potentially sight threatening

  • Retinal tear (fig 1 …

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