All the materials are imported, huge import taxes. That is why food, like tropical fruits, are so unconscionably expensive here, even with the proximity of Brazil where great fruit is rotting in the fields. Anything produced here is cheaper (though if manufactured probably not as good quality).
Anyone coming to Argentina should get anything like eyeglasses or anything else essential or quality) all taken care of first, you will pay many times what you would pay in a country with a more open economy.
Unless you have a good firsthand recommendation, do not go to opticians to have your eyes tested, as the profession does not really exist here (and is completely unregulated), and there are some real shysters. There are some good non-medical opticians that can test your eyes properly, but they are a real minority here. In Canada, most opticians are better than opthamologists when it comes to testing for lenses.
As someone who needs glasses to read, i know the importance of good eyewear. Get an opthmologist prescription (or use one from your home country), and bring it to a quality eyeshop that insists on prescriptions.