Users adjust their 'prescription' by turning dials located on the sides of the frames. The dials control two lens that are overlaid on one another.
"By sliding one element over the other, the lens changes its 'prescription' to give clear vision instantly," explains Eyejuster's website. "We've obsessively modelled, simulated and measured them to provide outstanding optical clarity and comfort."
Eyejusters creators added: "Each SlideLens is a pair of lenses with a special shape that you are able to see if you hold the lens on its side and reflect light from the surface. When these lenses are slid across each other (left-to-right), their combined shapes act as if they were one lens with a changing spherical surface."