More than one billion people in the world don't have glasses but need them.
These people live in parts of the world where there aren't many opticians.
For example, in parts of Africa there is only one optician per million people.
But now, these is a scientist who has found a solution to the problem.
Joshua Silver has invented glasses which don't need an optician.
They look like a pair of normal glasses but there is a pump on each side with silicone oil.
First, you turn a wheel which controls the pump.
The pump pushes the silicone oil through the pipe and it moves into the lenses.
The shape of the lens changes and you turn the wheel until you can see correctly.