I didn't find any evidence that he had lost his sight.
Could you, perhaps, be referring to Andea Bocelli?
Roberto Alagna, the renowned French-Italian tenor, did not lose his sight. He is not blind, and there is no record of him experiencing any significant vision loss. It is possible that there may be confusion or misinformation regarding his eyesight. It's always important to verify information from reliable sources before accepting it as true.