Table 3 Effect of no eyeglasses sales on process completed

No sale Treatment (control group as reference)

0.545 (0.219 to 1.355)

0.192

0.488^* (0.253 to 0.940)

0.032^*

0.424^* (0.201 to 0.897)

0.025^*

-3.917 (-6.798 to -1.036)

0.008^**

Characteristics of local refractionists

 Male

0.418 (0.153 to 1.139)

0.088

0.766 (0.383 to 1.535)

0.453

0.771 (0.354 to 1.680)

0.513

-1.688 (-4.778 to 1.402)

0.283

 Age (age < 30 as reference)

  30–39

2.106 (0.706 to 6.284)

0.182

1.367 (0.648 to 2.885)

0.412

0.878 (0.379 to 2.033)

0.761

1.373 (-1.914 to 4.660)

0.411

  ≥ 40

2.194 (0.612 to 7.873)

0.228

1.072 (0.457 to 2.515)

0.873

0.629 (0.237 to 1.669)

0.352

1.332 (-2.436 to 5.100)

0.487

Facility characteristics

 Public (vs private)

0.175 (0.067 to 0.456)

 < 0.001^***

1.970 (0.961 to 4.037)

0.064

0.057 (0.026 to 0.128)

 < 0.001^***

1.718 (-1.295 to 4.732)

0.262

 Located in Xi’an (provincial capital)

0.552 (0.182 to 1.675)

0.294

2.017 (0.999 to 4.071)

0.050*

1.226 (0.558 to 2.691)

0.612

-0.675 (-3.763 to 2.412)

0.667

SP characteristics

 Age (years)

0.796 (0.568 to 1.115)

0.185

1.036 (0.849 to 1.264)

0.726

1.091 (0.882 to 1.349)

0.423

0.859 (0.013 to 1.705)

0.047

 Male

1.978 (0.604 to 6.472)

0.260

1.585 (0.712 to 3.526)

0.259

0.510 (0.209 to 1.244)

0.139

-0.156 (-3.650 to 3.338)

0.930

 Spherical power, > − 3.0 D as reference

  ≤ − 3.0 D and > − 6.0 D

3.034 (0.945 to 9.744)

0.062

5.508 (2.317 to 13.095)

 < 0.001^***

0.661 (0.271 to 1.613)

0.364

3.493 (0.131 to 6.855)

0.042^*

  ≤ − 6.0 D

11.277 (1.250 to 101.773)

0.031^*

2.828^* (1.129 to 7.082)

0.026^*

0.904 (0.327 to 2.496)

0.845

3.891 (-0.088 to 7.870)

0.055