Nearly 70 percent of eighth grade students in China had poor eyesight last year despite government efforts to combat nearsightedness, or myopia, a new report showed.

The report on the health of the country's primary and middle school students, released by the Ministry of Education on Wednesday, found that 68.8 percent of eighth graders had poor eyesight last year, up 3.5 percentage points from 2015.

The rate among fourth graders was 38.5 percent, up 2 percentage points from 2015.

The report was based on a survey of almost 200,000 fourth and eighth grade students last year by the ministry's National Assessment Center for Education Quality.

Questionnaires were also sent to more than 6,000 primary and middle school principals and 30,000 teachers.

The survey also found that children in urban areas have poorer eyesight than their rural counterparts. In urban areas, 76.6 percent of eighth graders had poor eyesight, compared with 60 percent in rural areas. For fourth graders, it was 46.6 percent in urban areas and 30.4 percent in rural areas.

China rolled out a guideline last year to curb the rise of myopia among children and teenagers. The guideline, jointly issued by the Ministry of Education, the National Health Commission and six other departments, said the overall myopia rate among Chinese teenagers should be reduced by over half a percentage point a year from 2018 to 2023. In high-incidence provinces, the reduction should reach 1 percentage point a year.

Parents and schools should work together to ensure teenagers get at least one hour of outdoor activity a day and enough sleep, with a reduced academic workload and less time spent using electronic devices, the guideline said.

In an instruction in August 2018, President Xi Jinping said the high incidence of myopia among students, which is affecting more children at a younger age, is a major problem with implications for the country's future.

A research report released by the World Health Organization in 2017 said there were 600 million nearsighted people in China-nearly half the country's population.

Qi Bei, vice-president of the China Optometric and Optical Association, said increased school workloads and greater use of electronic devices are regarded as major reasons for the increased frequency and severity of nearsightedness among primary and middle school students.

A staggering 900 million pairs of eyeglasses are sold in China every year, Qi said.

It has been proven that more outdoor activities, sufficient indoor lighting, maintaining a proper distance from books and screens and taking regular breaks can help prevent the occurrence of myopia, he added.

The ministry's report also found obesity rates among fourth and eighth grade students have risen.

About 9.7 percent of eighth graders were obese last year, up 2.2 percentage points from 2015, and the obesity rate for fourth graders reached 8.8 percent last year, up 1.9 percentage points.