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The Impact of Eyeglasses on the Academic Performance of Primary School Students in China

Location: Yongdeng and Tianzhu Counties, Gansu Province
Sample: 18,902 students in 25 townships
2004 to 2005
AEA RCT Registration Number: 

Approximately 10 percent of primary school age children in developing countries are thought to have vision problems, yet very few of them wear glasses. Researchers evaluated a program in rural China which offered free glasses to primary school children. Around 70 percent of eligible students accepted the glasses, and the program substantially increased test scores for students who accepted and wore the glasses.

Policy Issue 

The Millennium Development Goals have placed strong emphasis on the promotion of universal primary education. Yet simply enrolling children may have little effect on long-term education outcomes if children do not acquire academic skills when they are in school. Learning may be inhibited by poor vision, which can prevent children from reading, writing or following teacher instruction. Approximately 10 percent of primary school age children in developing countries are thought to have vision problems, and although most of the time these problems can be corrected with properly fitted eyeglasses, very few children in developing countries wear eyeglasses. To date, there has been very little research on the impact of poor vision on school performance in developing countries.

Context of the Evaluation 

China has achieved nearly universal primary school enrollment, with only 4 percent of adults aged 25 to 29 having no formal schooling. Each county in China has a Center for Disease Control office, which conducts regular physical exams of all students, including eye exams. The results of the physical exams are given to the school' s teachers, who are expected to convey the information to parents. Despite the availability of information on children' s vision problems, however, one study in China in 2000 found that while 12.8 percent of children age 5-15 had vision problems, only 21 percent of those with vision problems had glasses. Eyeglasses can be purchased in most county capitals for $10 - $15, but many in China believe that wearing glasses causes vision to deteriorate faster.

A schoolboy shows off his new glasses in Gansu Province, China.
A schoolboy shows off his new glasses in Gansu Province, China.
Details of the Intervention 

In 2004, researchers, in cooperation with Gansu' s Bureau of Health, implemented a randomized evaluation to examine the impact of providing eyeglasses to students in grades 4-6 with poor vision. The trial involved 18,902 students from 25 townships in two counties, Yongdeng and Tianzhu. The townships were randomly divided between treatment and comparison groups, in which either all or none of the township' s schools received eyeglasses. In total, 1,528 students in treatment townships were offered eyeglasses (of which 1,066 accepted) while 1,001 students in control townships were not offered.

At the end of the 2003-2004 school year, a baseline survey collected data on student characteristics, academic test scores, and visual acuity in both treatment and comparison schools. The students with poor vision in treatment schools who would be entering grades 4-6 in the fall of 2004 were offered free eyeglasses. Later that summer, optometrists contracted by the project traveled to each township to conduct more in-depth eye tests for students with poor vision who accepted the offer and had permission from their parents. If poor vision was confirmed, the optometrist would prescribe appropriate lenses, with a limited choice of colors and styles for the eyeglass frames. At the end of 2004-2005 academic year, grades for the fall and spring semesters were collected to evaluate the impact of the eyeglasses on test scores.

Results and Policy Lessons 

Based on the vision test administered by the optometrist (which involved asking patients to read a standard eye chart, similar to those used elsewhere), 13.4 percent of children had poor vision, and only 2.3 percent of children with vision problems had eyeglasses before the project began.

Impact of eyeglasses: Wearing glasses for one year increased average test scores by 0.16 to 0.22 standard deviations. These effects are large; similar tests given to children in grades 4 and 5 in Gansu province show that an additional year of schooling leads to an increase of roughly 0.44 standard deviations in test scores. This implies that these impacts are equivalent to an additional one third to one half of a year in school. Put another way, providing glasses raised learning per year of school by 33 to 50 percent.

Take-up of eyeglasses: Despite such high returns to wearing eyeglasses, only 70 percent students with poor vision in the treatment schools agreed to be fitted for eyeglasses, even though the glasses were provided at no cost. The main reasons for turning down the offer were the objection of household head (31 percent of refusals) and refusal on the part of the child (17 percent). Results indicate that children with less bad eyesight were more likely to decline the glasses, having less reason to wear them. A more unexpected result is that girls had a much lower probability of accepting eyeglasses than boys: 74 percent of boys received eyeglasses while only 66 percent of girls received them.

Glewwe, Paul, Albert Park, and Meng Zhao. "A Better Vision for Development: Eyeglasses and Academic Performance in Rural Primary Schools in China." Working Paper, June 2016.