* Sees sales growth up 6-9 pct in 2012, including acquisitions
* Year net profit up 9.4% at 505.6 mln euros, forecast 523 mln euros
* Sales up 7.7 percent at 4.19 bln euros
* Operating margin 17.9% vs 18.1% in 2010
* Dividend up 2.4% at 0.85 euros a share, eps up 10.7% (Adds further details)
By Elena Berton
PARIS, March 1 (Reuters) - Essilor International SA , the world's largest maker of corrective eye lenses, predicts continued revenue growth and a slight improvement in operating margin in 2012, after profitability last year was knocked slightly by higher costs.
"We see a rather strong 2012, perhaps stronger than 2011 in terms of demand, volume and value," Chief Executive Hubert Sagnieres told reporters on Thursday.
Essilor expects its underlying operating margin to rise to 18 percent in 2012 after dipping to 17.9 percent last year from 18.1 percent in 2010, while sales are predicted to rise by between 6 and 9 percent this year, including bolt-on acquisitions, after growth of 7.7 percent in 2011.
"In light of the company's stronger than expected current momentum in its core lens business, we feel that this guidance is very achievable," Merrill Lynch analysts said in a note to investors.
But the shares, which have risen around 7 percent since the start of the year, were down 1.1 percent at 59 euros by 1040 GMT, when the Paris market's CAC 40 index was down 0.3 percent.
Net profit rose 9.4 percent to 505.6 million euros ($676.3 million) last year, but missed the average market forecast of 523.13 million given in a Reuters poll of 17 analysts, with the result hit by higher restructuring, one-off and financing costs.
The dividend was increased to 0.85 euros per share from 0.83 euros last time, covered by earnings per share up 10.7 percent at 2.44 euros.
Sales increased 7.7 percent to 4.19 billion, lifted by acquisitions as well as the launch of new products such as the Optifog anti-fog lens range.
Excluding 29 bolt-on acquisitions made in 2011, like-for-like organic sales growth was 5 percent.
The company is now turning to emerging countries to drive growth and is aiming for 1.5 billion of sales in these markets by 2015, compared with 612 million in 2011. ($1=0.7476 euros) (Additional reporting by Noelle Mennella; Editing by David Holmes and Greg Mahlich)