An incredible incident occurred in Britain. A a 29-year-old man, who went at a clinic, claiming he lost sight at his left eye because of the intense orgasm he had the previous night. As the British Medical Journal revealed, the diagnosis of the first examinations did not give a clear picture of exactly what had happened and the doctors asked the young man to go back to the clinic after three days.

His second visit, according to the Daily Mail, was examined by another ophthalmologist who, having some suspicions, began to ask the 29-year-old for his sexual activity. The young man revealed to the doctor that in the evening before losing sight of one eye he had a very intense sexual intercourse. In fact, he appears to have been practicing a tactic known as “Valsalva Maneuver”.

What happens is that during the orgasm handling of valsava can increase retinal pressure, break a vessel and cause chitotoxic bleeding.

In fact, blindness is not the only side effect that this tactic might cause, as the intense pressure on the blood that goes into the brain may also lead to amnesia, as another research from 1998 concluded.