A man was forced to seek medical help after going temporarily blind every time he had sex, reports The Daily Mail, London.
The unnamed patient would lose his sight every time he climaxed during intercourse.
Bafflingly, the blindness would never occur while performing any other strenuous exercise, the NCBI ROFL blog claimed.
The original report, published by the Department of Ophthalmology at Glostrup Hospital, University of Copenhagen, revealed the cause of the condition to be vasoconstriction, where the muscle walls contract around a blood vessel, restricting the flow of blood.
Vasoconstriction is the same condition that causes erectile dysfunction.
Doctors had earlier speculated that an embolism was causing the man's blindness.
The report said: ‘Hypothetical mechanisms of transient monocular visual loss in our patient include vasoconstriction or embolism in the arterial blood supply of the eye.
‘The repeated and completely transient nature of our patient's symptoms supports the fact that embolism was not involved.'
The patient was eventually treated using drugs to widen his blood vessels.
NCBI ROFL is a blog written by two PhD students in Molecular and Cell Biology at UC Berkeley.
It features scientific articles with humourous subjects from the PubMed medical database.