Picture this: Your contact lenses are running low, and you soon realize that your last prescription has expired. With a busy week ahead, squeezing in a visit to the eye doctor would be a struggle.

The vitreous is the gel-like fluid that fills the eyes. It is full of minuscule fibers that attach to the retina. As people age, the vitreous fibers separate from the retina, which may affect vision.

When Warby Parker started in 2010, it had a simple pitch: upend traditional optometry by providing an online marketplace where customers can buy prescription lenses at prices that don’t make them want ...