Updated from 8:56 a.m.

Bausch & Lomb


, the No. 1 maker of soft contact lenses by market share, made a $600 million all-cash bid Thursday for

Wesley Jessen VisionCare


in an attempt to pre-empt a planned acquisition by Wesley Jessen.

Just three days ago, Wesley Jessen, based in Des Plaines, Ill.,

agreed to buy rival

Ocular Sciences

(OCLR) - Get Report

in an all-stock deal valued at about $413 million.

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Investors clearly favored the Bausch & Lomb overture, as shares of Wesley Jessen leapt 36%, or 9, to 33 7/8 in early afternoon Thursday trading. Meanwhile, Bausch and Lomb was down down 1 1/6, or 2%, to 55 5/16 and Ocular Sciences was down 3/4, or 4%, to 16 1/2.

Under the terms of its proposal, Bausch & Lomb, based in Rochester, N.Y., is valuing Wesley Jessen at $34 a share, a 37% premium to Wesley Jessen's closing price Wednesday of 24 7/8. However, that price is likely negotiable. "I wouldn't be surprised to see the price go up," said Suey Wong, an analyst with

Robert W. Baird & Co.

"There may be other buyers." He rates Wesley Jessen a market perform and his firm participated in a secondary offering for the company last May.

A list of other buyers may include

Johnson & Johnson

(JNJ) - Get Report

, the largest maker of soft contact lenses by revenue.

Bausch & Lomb said the acquisition would add to earnings per share in 2001 and is not subject to any financing contingencies.

The day of the announcement of the Wesley Jessen-Ocular Sciences deal, shares of Wesley Jessen closed down 8% on worries that the deal made the company a less likely acquisition target. The shares have since rebounded.

Wesley Jessen is the No. 1 developer, manufacturer and marketer in the $750 million specialty soft contact lenses market, which includes cosmetic lenses that change or enhance the wearer's eye color. Ocular Sciences, based in South San Francisco, Calif., also manufactures and markets soft contact lenses, including a comfortable clear disposable lens that also has been gaining share in the marketplace.

"Our offer is clearly superior and more beneficial to Wesley Jessen shareholders than the proposed no-premium merger between Wesley Jessen and Ocular Sciences," said William Carpenter, chairman and chief executive of Bausch & Lomb, in a statement.

Neither Wesley Jessen nor Ocular Sciences were available for comment.