Corvis Corp. announced yesterday that it will lay off another 180 people, or about a quarter of its remaining staff, with most of the cuts affecting its research and development staff at the corporate headquarters in Columbia.

The layoffs represent the network equipment firm's eighth restructuring in the last year and a half. In the last year, Corvis's sales have declined about 90 percent because its telecommunications carrier customers stopped upgrading their networks.

The latest reduction, along with a previously announced layoff of 164 French employees, will bring the company's workforce to less than 500 by the end of the first quarter of this year. In May 2001, Corvis had 1,625 employees.

"Current market dynamics remain difficult for Corvis and every equipment provider in our space," David Huber, chairman and chief executive of Corvis, said in a statement. "This initiative is part of our continuing effort to structure the business for the long term."

In recent weeks, Corvis's executives had been hinting that they would have to make additional cost-cutting moves. During its third quarter the company burned through $35 million in cash, and it wants to get that down to $25 million a quarter or below, said spokesman Andy Backman. The company also said it will report that it has $504 million in cash and investments when it releases its fourth-quarter financial results Feb. 6.

Corvis, founded in 1997, makes hardware and software products that transport Internet data thousands of miles over fiber-optic lines -- products that are less in demand now, as telecommunications carriers have excess capacity in their networks and little cash to spend.

With its revenue in a deep trough, Corvis is trying to focus on lab-testing its gear with five of its six customers, hoping successful trials with those companies will eventually result in a handful of large contracts, Corvis President Jim Bannantine said recently.