SCOTTSDALE, Ariz. — The Giants need second baseman Joe Panik to hit, and for Panik to hit, he needs his eyesight, which he no longer takes for granted.

Panik said Monday that he can connect his season-altering concussion last year to his .215 batting average over the 57 games after he returned from the disabled list.

Even after Panik was cleared to play, his eyesight did not return to normal. It stayed a bit fuzzy. He could not see pitches as well and compensated by opening his stance, which allowed him to see the ball longer — but that prevented Panik from reaching outside pitches and hitting breaking balls.

“That’s a big thing,” he said. “I’ve got to get back to using the whole field.”

Though most ballplayers exercise their legs, arms and core in the offseason, Panik performed eye exercises that specialists told him would help restore his vision the way it was before then-Tampa Bay Rays lefty Matt Moore beaned him June 18.

“I’m just trying to stay on top of the strength of my eyes,” Panik said.

The exercises — and time — have helped. Panik reports he can see fine and has no lingering concussion symptoms. Panik worked in the cage Monday with hitting coach Hensley Meulens to keep his stance “in line” with the pitcher so he again can try to be the Panik who hit over .300 in each of his first two seasons.

Cueto delayed: Johnny Cueto did not join the other pitchers on reporting day. He remained in the Dominican Republic to tend to his father, Domingo, who is ill.

A team spokesman said Cueto’s arrival would be delayed “a couple of days.”

The Giants need to accelerate Cueto’s throwing so he is ready for the World Baseball Classic, which begins March 6.

Bumgarner contract: All remains silent on the Madison Bumgarner extension front.

Bumgarner said his agent and the Giants did not initiate discussions over the winter. Team President Larry Baer likes to announce extensions at the Play Ball lunch the Friday before the season begins, but Bumgarner said, “If that’s going to happen, it’ll have to start after today, because we haven’t talked.”

Bumgarner’s contract situation is unusual and sticky.

He will earn $11.5 million in 2017, the final guaranteed year of a $35 million deal he signed in 2012. At the time, that was the richest contract ever awarded to a player with less than two years of service time. But now, Bumgarner is vastly underpaid compared with others of his stature.

Clayton Kershaw will earn $35 million, although he has two years more service time.

The Giants hold $12 million options on Bumgarner for the 2018 and ’19 seasons. He cannot be a free agent until 2020. Much can happen in three years, which makes it tricky for the Giants to discuss a nine-figure extension now. Such an extension also could raise the Giants’ luxury-tax bill.

Henry Schulman is a San Francisco Chronicle staff writer.