When Warby Parker opened a flagship store in New York City, many people were shocked. No one expected the digital eyewear disruptor to expand their business to a bricks-and-mortar store. 

Speaking at Internet Week this week, Neil Blumenthal, one of Warby Parker's founders, said the move was strategic. 

"We believe the future of retail is at the intersection of e-commerce and bricks-and-mortar," he said. "People think it's crazy that we went and signed a 10-year lease in SoHo, next to Ralph Lauren, across the street from the Apple Store. But we have actually been dabbling in bricks-and-mortar for about three years, almost as long as we have had the website open."

When it launched, the start-up offered customers the option to try a number of glasses at home, he explained. 

"That in itself was a physical form of sales, but what happened was that within 48 hours of launch, we were overwhelmed by demand and had to suspend the home trial program. And people would call up and say, 'Hey, can we come to your office and try on glasses?' And we would say, 'Uh, we are working out of my apartment.'  

"People would come in, and we would lay out the glasses on the dining room table. And we thought it was going to be a sub-optimal experience, but it ended up being a very special experience in that we could build relationships with our customers. They could try on all the glasses. We started to realize maybe there was a place for traditional bricks-and-mortar retail." 

The idea for the Warby Parker showroom and pop-ups was born. When those raked in profits, the company decided to open a flagship to anchor the brand. Now, 50 percent of their foot traffic and sales are driven by word-of-mouth, which Blumenthal says was exactly the point. "Our philosophy from the get-go has always been: How can we grow this primarily through word-of-mouth?

"It's about how can we create special moments. When you walk into the store, most people are really surprised, because it doesn't look like any place they have ever been that sells eye glasses."