When reading, he had difficulty following the flow of sentences.
At least once, he thought he was done with his sandwich because he couldn't see the sandwich half still sitting on the left side of his plate.
Then Gerace learned about a new therapy called NovaVision Vision Restoration Therapy that could improve his field of vision.
After seven months of therapy, Gerace says he now can see what's on the other side of the centerline when he's in the car with his wife.
"If I look straight ahead, it could be a white truck or a white elephant heading up the road. I see something. Before, I couldn't see left of centerline," says Gerace, 55, who lives in Springfield, Pa., a southwest suburb of Philadelphia.
"I can't distinguish it, but I'm picking things up, which is great. (The therapy is) drawing my attention to it," he says.
VRT is being offered through 19 places worldwide, including Washington County Hospital at Total Rehab Care in Robinwood Medical Center.
The noninvasive therapy addresses visual field cuts in patients who had a brain injury such as a stroke, says Tim Burkhart, occupational therapist and certified brain injury specialist at Total Rehab Care.
For example, people with a left visual field cut would think they were seeing everything in front of them, but they're not seeing everything on the left, Burkhart says.
Through stroke or brain injury, some of the neurons in the occipital lobe, the area in the back of the brain that interprets vision, can become damaged, he says.
VRT attempts to rewire the brain using the concept of neuroplasticity, in which undamaged neurons can be stimulated to take up the slack for damaged neurons, improving the field of vision, Burkhart says.
This is done in the person's home using a laptop computer with a headrest and mouse.
Leaning into the headrest, the person stares at a fixed point on the computer screen while visual stimuli - dots - pop up throughout the visual field.
Whenever a dot pops up or the center dot changes color, the person clicks the mouse to indicate it was seen. The program uses sequences with many of the lights along the boundary between the areas the person can and cannot see to try to expand the field of vision.
The lighted dot is not doing anything to the eye, Burkhart says. The therapy is based on the person paying attention to where the lights come on.
This is done for 30 minutes, twice a day, for six days a week, for six months, Burkhart says. The device records accuracy rates and response times.
People are screened to see if they are eligible for the therapy, Burkhart says. Age and the amount of time since the injury are not a factor. Then tests are done to determine what vision the person has and doesn't have, and what area they cannot see.
Total Rehab Care has 12 to 15 clients participating in the therapy, which it started offering in March, Burkhart says.
While there is a lot of interest in the therapy, it is still fairly new and is not covered by Medicare or insurance, Burkhart says. VRT costs $6,500.
According to NovaVision, based in Boca Raton, Fla., more than 800 people have been treated with VRT.
More than 65 percent of patients who underwent just six months of treatment showed measurable improvement, says Navroze Mehta, chief executive officer of NovaVision, in a recent phone interview.
Burkhart says VRT is not expected to be a 100 percent cure.
Of the participants Burkhart has worked with, about half are seeing good results while it's still too soon to tell for the others. None of them have completed their first six months yet.
Burkhart says some therapy participants come from as far away as 8 to 10 hours because there aren't many places offering this therapy yet.
Gerace says he was told by doctor(s) there wasn't anything available to help him with his vision.
He persisted, searching the Internet for anything that could help with visual field cuts. It wasn't until he learned the technical name of his condition, homonymous hemianopsia, and plugged that into a search engine, that he discovered NovaVision's therapy program.
Gerace says he almost went to the University of Miami for the therapy or The Wilmer Eye Institute at Johns Hopkins, until learning the therapy was going to be offered through Albert Einstein Medical Center in Philadelphia.
"We were ready to go anywhere," says Gerace, whose stroke forced him to retire from selling textbooks.
"Right now, it's added total quality of life," he says.
Unable to see action on the left side of the ball field at his son's baseball games in April, Gerace says sitting behind home plate at Citizens Bank Park a month ago he was able to follow the baseball from the left-handed pitcher to the batter who hit the ball back to the pitcher, who then threw to shortstop to start a double play.
"Before, I wouldn't have seen the pitcher catch it" - something he used to take for granted, Gerace says.
After finishing his first six months of therapy, Gerace started his second set.
"To me, it's such an easy thing to do because it's my only hope," he says.