Millions of eye drop products have been recalled over concerns they may not be sterile, according to an enforcement report from the U.S. Food and Drug Administration.

A nationwide recall of eye drops sold at major retailers like CVS, Walgreens and Kroger has expanded to include more than 3.1 million bottles over concerns the products may not be sterile.

K.C. Pharmaceuticals, Inc. initiated a voluntary recall on March 3, affecting more than three million eye drop products due to concerns that they may not be sterile.