MILAN (Reuters) – Italian eyewear group Safilo posted on Tuesday a 8.4% rise in first-quarter sales at constant exchange rates, driven by the resilience of the prescription frames business and a rebound of sunglass sales, particularly in Europe. The maker of frames for Hugo Boss and Tommy Hilfiger said in a statement that January-to-March sales came in at 282.6 million euros ($297.61 million), while adjusted core profit margins rose to 11.3% from 10.3% a year earlier. The company said it had witnessed a demand pick-up in Europe thanks to its own brands and key licences, and that North America …