CORNING, N.Y., April 15 -- Corning Incorporated credits demand for optical fiber and photonics products with helping to lift 1999 first quarter earnings to $0.36 per share, an increase of 33 percent over the $0.27 per share earnings for the same period in 1998. Net income for the first quarter of 1999 totaled $86.5 million, an increase of 39 percent over last year's first quarter income of $62.1 million.First quarter sales were $892 million, increasing 12 percent over 1998 first quarter sales of $795 million. This sales growth was driven by gains in the optical fiber and cable and photonic technologies businesses. First quarter 1998 sales and income were adversely impacted by economic downturns in Asian markets.