Q&A with our GP: why do I see red lights when I'm walking in the dark?

Dr David Roche / 27 March 2015

Saga Magazine's Dr Roche on possible symptoms of glaucoma



Glaucoma symptoms

While walking along city streets in the dark (ie with street lamps) I have had three episodes of seeing small, bright-red lights darting and zig-zagging about on the pavement or on walls. The episodes last for less than a minute, then my sight returns to normal.

I also suffer from acute angle-closure glaucoma. Are these ‘lights’ anything to worry about?


Low light conditions will often trigger episodes of acute angle-closure glaucoma because in the low light the pupil dilates and sparks off the episode. I ought to point out that acute-angle closure glaucoma is very different from chronic open-angle glaucoma and the two have very different symptoms and treatments.

An acute-angle attack usually involves haloes round lights, a painful red eye and blurred vision, usually coming on quickly.

If an episode like this occurs you need to see an eye specialist or go to an A+E department as soon as possible.

Apart from occurring in low light you do not seem to have any of the key features of acute angle-closure glaucoma. I presume the visual abnormality you have noted does not progress and resolves on all occasions.

I would suggest you go to see your eye specialist and make sure your problem is well controlled. There may be some more innocent cause.

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