Amid a lull in the economy, department stores have been seeing sales of sunglasses increase by up to 45 percent in the early summer season compared to the same period last year, the industry said Monday.

The three major department stores Lotte, Hyundai and Shinsegae saw sales of summer fashion accessories go up 28 percent, 27.5 percent and 44.9 percent on-year in May, respectively.

The increase was largely attributed to seasonal sales, which started running about two weeks earlier this year due to the unusually hot weather. June is traditionally considered the peak time for sales of sunglasses, but the early arrival of summer changed the trends.

"Many customers are also opting for fashion accessories that accentuate their clothes, such as scarves and sunglasses, rather than expensive garments, due to the sluggish economy, so sales of sunglasses have shot up," said a staffer at Lotte.