China has fined Johnson & Johnson, Nikon Corp. and five other makers of eyeglasses and contact lenses on price-fixing charges in its latest effort to use anti-monopoly law to control consumer prices.

Manufacturers were fined a total of 19 million yuan ($3.1 million) for setting minimum prices for retailers and limiting their ability to offer discounts, the Cabinet’s planning agency said Thursday.

Other companies fined included Essilor International SA of France, Germany’s Car Zeiss AG, Hoya Corp. and Bausch + Lomb, owned by Canada’s Valeant Pharmaceuticals International Inc. One Chinese company was fined, Shanghai Weicon Optics Co.

Setting minimum prices is common in some markets to help companies maintain an image as a premium brand. But lawyers say Chinese regulators appear to regard such limits on distributors as illegal.

In August, six suppliers of baby formula were fined a total of $109 million on similar charges.

Investigators have targeted contracts that set minimum retail prices as prohibited “vertical price-fixing” under China’s 2008 anti-monopoly law. Most targets so far have been foreign-owned.

Officials and state media complain foreign suppliers of products from milk to luxury cars overcharge Chinese consumers. Automakers have rejected the accusation, saying higher prices in China are due to import taxes and distribution costs.

The latest investigation began in August after a complaint from the public, the National Development and Reform Commission said.

“Findings showed that some manufacturers had exerted price control on distributors and retailers, which violates anti-monopoly laws,” the agency said on its website.