Why? Its perfectly explained in tatamblog (spanish!):
Does it happen to you that when you exit from a dark spot to the lightly exterior, or that when you look directly to a light bulb that is very shiny you sneeze? If the answer is yes, ... you may have ACHOO syndrome (autosomal dominant compelling helio-ophtalmic outburst syndrome)
Very curious syndrome that makes me laught a bit every time it happens to someone near me.
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