Corning (NYSE:GLW) released strong first-quarter 2019 results early Tuesday, detailing continued broad-based growth across each of its five core business segments.

But the glass-technology leader also reduced forward guidance for its single largest segment, optical communications, leaving shares down nearly 6% today in response. Let's dive in for a more comprehensive idea of how Corning started 2019 and what we should expect going forward.

Spool of Corning optical fiber.

IMAGE SOURCE: CORNING.

Starting with the headline numbers, Corning's first-quarter core sales grew 13% year over year, to $2.85 billion. That translated to a 22% increase in core earnings, to $365 million, and 29% growth in core earnings per share, to $0.40. Corning returned $414 million to shareholders through dividends and share repurchases this quarter.

As I noted last week, most analysts were modeling lower core earnings of around $0.39 per share on revenue of $2.82 billion.

Corning CFO Tony Tripeny called it "an excellent first quarter, with strong performance across the company," elaborating:

[F]our of our five segments achieved double-digit sales growth year over year. This strong growth resulted from our technology and manufacturing leadership. We are benefiting from recent investments including expansions for optical fiber and cable; Gen 10.5 display glass; gasoline particulate filters; and multiple development projects such as Gorilla Glass for mobile devices and automotive. We continue to invest, and we expect to grow sales significantly in 2019 and beyond.

A closer look

On Corning's segment performance, optical communications sales soared 20% year over year, to $1.064 billion, driven by both Corning's recently closed acquisition of 3M's communications markets division and sales to carrier and data center customers. Optical segment net income grew 30%, to $142 million.

Display technology segment sales grew 10%, to $818 million, in line with expectations, as price declines continued to moderate and Corning's display-glass volume outstripped the broader industry's mid-single-digit percentage growth. Segment net income climbed 12%, to $208 million.

Environmental technologies sales increased a better-than-expected 12%, to $362 million, driven by demand in the heavy-duty diesel and gasoline particulate filter markets. Segment net income rose 6%, to $55 million.

Specialty materials segment revenue similarly climbed 11%, to $309 million (above Corning's mid- to high-single-digit target), as OEMs continued to flock to Corning's mobile consumer-electronics glass products, including the latest variants of Gorilla Glass. Segment net income grew 7%, to $49 million.

Finally, life sciences was the lone single-digit achiever, with sales rising 5%, to $243 million, albeit outpacing growth from the broader life-sciences industry. Segment net income jumped 15%.

On Corning's light guidance

However, Corning also told investors it now expects full-year sales growth of "just" 10% from its optical communications segment -- down from its previous outlook for a low-teens percent increase. Corning blamed a shift by an unnamed "major fiber-to-the-home customer" in the timing of a large deployment by one quarter earlier than expected.

Meanwhile, Corning continues to see its display technologies business volume outgrowing the broader industry's mid-single-digit percent increase. Environmental sales are now expected to climb by at least 10% (up from Corning's prior target for high-single-digit growth), life sciences should continue to outrun the broader market's low- to mid-single-digit rise, and specialty materials sales should end higher, with its pace on how quickly OEMs adopt Corning's latest specialty innovations in support of their newest product launches.

Altogether, Corning continues to expect both consolidated core sales and earnings per share to increase in 2019. But our fickle market is unsurprisingly displeased that the company effectively tempered the near-term growth outlook for its biggest business -- even though the move was the result of a shifted (not lost) deployment from within that business.

Viewed through that lens, I can't help but think this knee-jerk reaction to an otherwise solid report is overblown.