Wal-Mart has cut 91 jobs at its optical lab in Dallas after installing new manufacturing equipment.

The lab, which is one of three where Wal-Mart makes prescription eyeglasses, will now employ 430 people.

While trade policies were a big issue in the presidential election, manufacturing jobs are still being lost in the U.S. to automation. Last year, Wal-Mart said it would spend $10 million to upgrade manufacturing equipment at its Fayetteville, Ark.; Crawfordsville, Ind.; and Dallas optical labs.

The other facilities aren't affected by the decision, said Wal-Mart spokeswoman Anne Hatfield.

Prescription eyeglasses are the only product that Wal-Mart manufactures, start-to-finish, in-house. The three labs serve 3,500 Wal-Mart stores with optical centers. The Dallas lab opened in 1995, and Wal-Mart started making eyeglasses in 1991.

According to an article published last year in Wal-Mart's employee publication, production at the Fayetteville lab runs 24 hours a day, with more than 620 people working in rotating shifts. The record for a single day of eyewear production at the lab was 11,000 pairs.

The laid-off Dallas optical staffers are being encouraged to apply at other local Wal-Mart operations in the Dallas area, said Hatfield. In addition to stores, Wal-Mart operates distribution centers in North Texas and a prescription home delivery division based in Carrollton that mails prescriptions across the U.S.

The manufacturing upgrades are part of Wal-Mart's "commitment to provide customers with the highest quality custom eyewear at low prices," Hatfield said. "We are realigning the lab to create better efficiency in our production process."

Laid-off employees stopped working at the facility on Directors Row on Nov. 9 and will be paid until Feb. 17 as required under the WARN Act, according to a letter sent to the Texas Workforce Commission.

Twitter: @MariaHalkias