In Spain, where parts of the country will be in the path of totality, finding certified protective glasses has become increasingly difficult, with many distribution points reporting they have run out.A notice posted at the entrance of Madrid's National Museum of Natural Sciences said its supply of protective glasses was exhausted.The museum was among 30 science institutions across the country taking part in a campaign organised by the government to distribute two million pairs of glasses for free.Some pharmacies in central Madrid still had supplies Tuesday, generally selling certified glasses for safely viewing the Sun for between three and four euros ($4.60) a pair.But Carles Sisquella, who runs an optical shop in Barcelona, said his store had been out of stock for 10 days."There are now a lot of people who obviously won't be able to get glasses," he said.Doctors warn that looking directly at the Sun during a solar eclipse can damage the retina, potentially harming the cells responsible for sharp central vision."I've been asking around since Friday, but they're nowhere to be found," a woman named Mabel told AFP in Barcelona after another fruitless search.'Gone in 30 minutes'The rush is being repeated across Europe.In Brussels, where about 90 percent of the Sun will be covered by the Moon, people were also racing to find glasses.With a seeming majority of opticians and pharmacists out of stock, pastry chef Arno Dossogne, 37, struck gold at a small opticians' store that received a last-minute shipment Monday afternoon."I got some for me, my boyfriend and a couple of friends whose online order got cancelled!" he told AFP."It was this or nothing. You can't mess around, or you'll burn your eyes."