A Silicon Valley start-up has developed a smartphone accessory that lets owners check their vision at home.

The results produced by EyeQue's VisionCheck gadget can be used to order new glasses from many retailers.

However, because a prescription is needed to purchase contact lenses in the US, there are limitations on its use there.

The BBC's Cody Godwin tried out the innovation at the CES tech show in Las Vegas.

Read and watch all our CES coverage at bbc.com/ces2019