The problems which Novak Djokovic had with his eyesight in his match against Rafael Nadal at the ATP Finals Masters in London could have been avoided.
It looks like he probably had some dust under his contact lenses which was irritating his eye. This can be very painful and even very dangerous if this scratch gets infected.
Most professional sports people choose daytime contact lenses to improve their eyesight as up until recently the only alternative to these apart from glasses was laser eye surgery. Whilst eye surgery is generally quite safe the potential side effects mean that it is not usually something they would choose until after their professional career is over.
That is why overnight contact lenses are a major advantage for sports people. Correcting your vision while you sleep means perfect vision during the day and the potential for this type of problem at a critical point in a competition is avoided.
In the video you can see how his contact lens problems may have changed the course of the game.
