used to refer to a lens (= curved piece of glass) that you can look through and see things clearly that are at various different distances

I have to wear thick varifocal glasses. 我必须戴上厚厚的变焦眼镜。

The lenses are varifocal, with three main areas that are blended into one to let you see sharply at all distances. 镜片是变焦的，三个主要区域融为一体，让你在任何距离都能看清。