Warby Parker is three weeks old and its online glasses store is proving so popular the brand’s in danger of burning out. But if it’s going to pose a real challenge to Luxottica, it needs to learn how to sustain that momentum. Audible subscribers can listen to all episodes of Business Wars ad-free right now. Join Audible today by downloading the Audible app. See Privacy Policy at https://art19.com/privacy [https://art19.com/privacy] and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info [https://art19.com/privacy#do-not-sell-my-info].