Glasses often slide down Huang Yina's petite nose. If she has been wearing them for a while, the rims of the frames leave marks on her face. And when she laughs, the glasses resting on her cheeks rise up. Although Huang owns about 20 pairs of sunglasses, she almost never uses them. "I like aviators but they don't fit my face right," she said. "I keep buying them, hoping they are different." Huang, who lives in New York, faces a problem that is common among Asians: eyewear not designed to accommodate the shape of Asian faces, a glitch the estimated €30 billion (HK$270 billon) industry is trying to fix. Although brands have been producing what are known as "Asian-fit" ranges for several years, those products are stocked mainly in Asian stores, a merchandising model that fails Chinese and other Asian customers who are increasingly shopping abroad. "I always buy in the West because the taxes are lower there," said Huang, unaware of the difference in fit. Like Huang, thousands of Chinese customers believe they are buying the same pair of tortoise Dior shades in Paris as they would have bought in Beijing but end up with frames that are ill-fitting. Other factors, including the relative immaturity of the eyewear business to other products, lack of consumer awareness and difficulty in stocking, mean brands have been slow to react. That may be changing soon, with the rapid rise in Asian global luxury spending. Although there are no concrete numbers for the size of the eyewear market, Giovanni Zoppas, the chief executive of Marcolin, one of the big three eyewear licensees - the others being Luxottica and Safilo - estimates it is upwards of €30 billion. "Wholesale, we are talking about €13 billion worldwide. Considering the usual mark-up in the industry, we could easily be talking about €30 billion," Zoppas said. Compared to other fashion categories, glasses are a relatively young product segment. Brands typically start with apparel and bags, expanding into leather goods, shoes, accessories and belts - items that are more closely linked to the core business. "Until five or six years ago, if you looked at the retail network of all the major brands, the space devoted to glasses was very limited," Zoppas said. He attributes the rise in prominence to two important factors - consumers were educated to protect their eyes from sunlight, and glasses evolved from being a medical aide to a style statement. Highlighting eyewear's rising significance, luxury conglomerate Kering announced in September last year it would end its 20-year relationship with Safilo and move the business in-house, citing double-digit growth in the premium segment. But what exactly is Asian-fit? According to Luxottica, it entails reducing a frame's curvature to better suit flatter faces, angle adjustments to the frame to make sure it does not press against prominent cheekbones and curved nose pads to sit comfortably on shallower nose bridges. Marcolin does not just have a broad Asian-fit category but further divides it into Chinese, Korean and Japanese, alongside Russian and Western fits. "In recent years, we have seen an increase in Asian-fit sunglasses, mainly for our Chinese customers," said Nicola Bonaventura, Safilo's director of proprietary brands. The company, which designs and produces eyewear collections for brands such as Gucci, Celine and Dior, says 5 to 10 per cent of its styles are made solely for the Asian market. Luxottica, the industry market leader, devotes about 70 per cent of its offerings exclusively for the Asian market. But product development director Alessandro Beccarini admits "there is no big awareness yet". "There is more complexity involved in assorting a double version of the same model but markets are definitely moving forward in this direction," Beccarini said. "Australia, the US and Canada, for instance, have significantly increased their Asian-fit orders and the other markets are steadily following." The company's goal is to eventually have collections that are 100 per cent suitable for Asian consumers.