Dr. Bernard Harris, Sr. Elementary School third-grader Rashad Solomon, 9, shows off his new glasses during event to mark the 1,000th pair of glasses given out to Baltimore public school students through the Vision for Baltimore program, on March 8, 2017. (Kenneth K. Lam/Baltimore Sun/TNS via Getty Images)

Three years ago, Johns Hopkins University researchers in Baltimore asked a seemingly simple straightforward question: Could the persistent gap in reading performance between poor students and wealthier ones be closed if they gave the poor students eyeglasses?
They knew that poorer students were less likely to have glasses than wealthier white children, but data were limited on whether simply helping children better focus on the page in front of them might improve their ability to master a skill essential for early learning. They screened several hundred second- and third-graders, gave two pairs of eyeglasses to the ones who needed them (about 60 percent of the group, based on a uniquely liberal prescribing standard) and then they tracked their school performance over the course of the year. The outcomes were notable enough even with the small sample size—reading proficiency improved significantly compared with the children who did not need eyeglasses—that the …