The Austrian called it a day on the penultimate stage of the race in the feed zone following an earlier tumble in which he fractured his clavicle bone.
Dimension Data confirmed the injury in a twitter post which will now cast doubt over whether or not Eisel will recover in time for the upcoming Classics season.
With Milan – San Remo taking place on March 22 the race is on for Eisel to overcome this injury in time.
The news compounds a miserable day for Dimension Data as last year’s winner, Mark Cavendish, suffered a puncture in the final kilometres of the fourth stage, resulting in him finishing more than five minutes behind the head of the field.
With hopes of defending his title now all but over, Eisel’s injury will serve a further blow to Cavendish who will lose one of his key lead out men for the immediate future.