Members of the Technical Engineering and Electrical Union (TEEU) at Bausch & Lomb in Waterford have voted to accept a cost saving plan put forward by management.
The deal will see workers take a pay cut of 7.5% - as well as other changes to their terms of employment.
The union said the proposals were particularly harsh, but that the alternative was unthinkable.
It was feared that the plant would be closed down if agreement was not reached.
The contact lens manufacturer employs 1,100 workers. Two hundred will lose their jobs under the cost-cutting plan.
The largest union at the plant - SIPTU - yesterday also voted to accept the package.