A teenager has injuries inside his eyes. A doctor finds out how it all began: with a seemingly harmless gimmick. Recorded by Astrid Viciano

When the boy came to my consultation at the clinic where I was working as a senior physician at the time, he didn’t really want to come out with the language at first. He sat taciturnly across from me. He briefly let me know that he couldn’t see properly. I wasn’t concerned at first, suspecting the teenager had probably become nearsighted and needed glasses. The boy was slim and had no previous illnesses.