If your company have issued a safety directive, based upon a risk assessment for the type of work that you do, then you will be breaking the law if you do not comply with the directive. This is because it's illegal to endanger anyone's safety, including your own. Also, your company will be breaking the law if they fail to ensure that you comply with the directive.
There are different types of safety glasses. Speak to whoever's responsible for safety matters at your place of work. Explain the problems that you're having and request that they examine the possibilty of providing you with an alternative form of eye protection.
Also, any good optician should be able to help you. While this will involve you spending some money (unless you can persuade your employer to pay for the referral), it might still be worth your while to consult an optician (or, in the first instance, your GP) as blurred vision is not normally a problem after removing safety glasses. There might be other problems with your eyes which you've previously been unaware of.
Chris