FRISCO -- For Mike Olt, keeping his eye on the ball has been much easier said than done.

After batting .288 with a Texas League-best 28 home runs and 82 RBIs for Double-A Frisco last year, Olt has struggled this season. He hit just .194 with the Rangers in Spring Training and batted .139 with one home run and six RBIs in 20 games with Triple-A Round Rock, striking out 32 times in 72 at-bats before being placed on the disabled list with vision problems.

"It started in Spring Training," Olt said. "It slowly got worse and worse during the season. It got really blurry when I blinked in my right eye. For a month, we couldn't figure out what was going on."

Olt went to a doctor, who discovered that the tear duct in his right eye was not producing any tears. He was given lubricating eye drops, which he now uses once a day. Olt started at third base and batted cleanup for Frisco on Friday night, going 1-for-4 with a two-run home run lined over the left-field wall in his final at-bat.

He struck out swinging in his first two at-bats before flying out to the left-field warning track in the sixth and going deep in the eighth. Olt is expected to play in Frisco through the weekend before returning to Round Rock on Monday.

While playing in the Dominican Republic last November, Olt sustained a concussion after being hit in the head with a pitch. He hadn't experienced vision problems before the concussion and believes that it led to the eye issues he's battled this season.

"They don't know for sure, but I never had anything wrong with my eye before," Olt said. "I know it was [related to the concussion]."

Olt, ranked as the Rangers' No. 2 prospect by MLB.com, thought he would eventually get back on track before his struggles were attributed to his eye problems. He last played in Round Rock on April 25.

"I kept trying to trick myself into thinking that I could get over this and it wasn't a big deal," Olt said. "Once it carried into my defense and I couldn't really see the ball just playing catch, that's when it started getting scary. At first, you think your swing is a little rusty and you're getting back in the swing of things. But it usually doesn't take me 70 at-bats to figure things out."

When standing in a batter's box, one doesn't have much time to recognize a pitch and react to it. The same holds true for someone who, like Olt, plays third base, where balls are often hit sharply and a quick reaction is required. So, when Olt started having trouble seeing the ball, it become nearly impossible to be productive.

"My first instinct was to flinch when I couldn't really see the spin. Obviously, you don't have time to flinch," Olt said. "I would get a curveball and couldn't even see it, couldn't react. Obviously, it was frustrating for me, but I just kept going along with it thinking I could get past it. I went up there with a game plan, was looking for a certain pitch and was getting it all the time. I just couldn't react to it. That's kind of been the story for the last three months."

Olt played in an extended spring game on Wednesday, going 4-for-5 with two doubles and a home run to center field, which came in his first at-bat. It was an encouraging performance for Olt, who could tell he was much more comfortable at the plate during pregame batting practice.

"That was the first time that I felt like my old self," Olt said. "I was able to lay off some good pitches and was able to get some pitches to hit, some mistakes, and for the first time in a long time, I was hitting those mistakes."

Olt was called up to the Rangers last September, when he made his Major League debut. In 16 big-league games, Olt hit .152 with five RBIs, striking out 13 times while drawing five walks. He is confident that if he makes it back to Round Rock next week as planned, he'll return to form.

"Tonight, I've got five at-bats. I'm going to try to get five homers," Olt joked before the game. "I'm not going to get back in the box and go 4-for-4 right away. It'll take a little time to get my timing back, but it's going to be a good adjustment now. I'm going to be getting better, not where I'm constantly making adjustments and not getting the results."