I return for my final checkup ready to give up the lenses but Minshull shows me the progress on reshaping my eye, and says that in some cases it can take longer than four weeks.

Jack: Yeah. Lenses may take some getting used to, but it feels so much better not being a four eyes.

One factory, which produces lenses for German brand Carl Zeiss in Guangzhou, started using robots four years ago in a bid to improve productivity and to cut costs.