Single vision, bifocal or progressive?

One distance or several

Separate three questions when reading a lens label: what distance is it designed for, what material is it made from, and what surface treatments does it have? Single vision answers the first question: one main prescribed viewing task, which may be distance or near. Bifocals contain distinct distance and near portions with a visible boundary. Progressives connect viewing powers through a gradual transition. None of these labels alone tells you the material index or whether an anti-reflective coating is included.

Single vision lenses provide one prescribed power. Multifocal lenses provide correction for more than one viewing distance. These are design choices, separate from brand, coating and material.

Make a task list

Write down whether you need distance driving, sustained desktop work or close reading. Ask the optician to demonstrate where you will look through the proposed lenses for each task, and what another pair might do differently.

A worked example

A single-vision lens can correct both myopia and astigmatism. “Single” does not mean there is only one number on the prescription. For example, a distance pair may have SPH, CYL and AXIS and still be single vision. If you mainly work at one fixed monitor, ask how a dedicated screen pair compares with an all-purpose progressive. This is a comparison of usable distance and field of view, not a rule that more zones are always better.