The fight between Lewis and Klitschko was to take place in December 2003, and Klitschko signed for a tune-up fight on 21 June 2003 as part of the undercard of Lewis' fight with Kirk Johnson for the IBO title, as the WBC would not sanction the fight for their title. Johnson, however, pulled out of the fight due to injury and Klitschko, due to his being in training for a fight on the same day as Lewis, took the fight on short notice. Immediately after he accepted, the WBC elected to sanction the fight as a title match and Lewis' The Ring title was also up for grabs in addition to his lineal title.  Klitschko, a 4-1 underdog, dominated the early going with many harder punches. He stunned Lewis in the second round with two hard rights, leaving a cut under on Lennox's left eye. In the third, Lewis landed a big right hand that opened a deep cut above Klitschko's left eye. Before the seventh round, the ringside doctor inspected the wound and deemed it severe enough to threaten eye damage if struck again, stopping the fight despite Klitschko's pleas to continue. Klitschko was ahead on all three judges' scorecards 58-56 (4 rounds to 2) at the time of the stoppage, but because the wound was a result of punches from Lewis, Lewis won by technical knockout.  Negotiations for a 6 December rematch began. After negotiations collapsed, Vitali defeated Kirk Johnson in a WBC Eliminator bout on 6 December date, setting up a mandatory rematch with Lewis. In January 2004, the WBC announced that it would strip Lewis of the belt if he let pass a 15 March deadline to sign for a rematch with Vitali. Shortly thereafter, Lewis announced his retirement and vacated the title. For years after this fight, Klitschko would still occasionally call out Lewis, despite the fact that Lewis has been retired since early 2004, for a rematch.  Around this time the Klitschko brothers moved from Hamburg, Germany to Los Angeles. In January 2004 they notified Universum that they would not re-sign when their contracts expired in April. Universum sued the brothers, arguing that their recent injuries had triggered a clause binding them beyond April. The suit was ultimately resolved in favor of the Klitschkos in November 2009.

Answer this question "Why did the fight stop?" by extracting the answer from the text above.
the ringside doctor inspected the wound and deemed it severe enough to threaten eye damage if struck again,