How to understand it
Useful zones and side blur depend on the design and fitting. Office lenses and general-purpose progressives can cover different distance ranges.
An example
For reading, the gaze usually moves into a lower area; looking far through that same area may blur the view.
A common mix-up
A progressive is not an electronic lens that automatically changes its whole surface for a task.
See the idea in a full guide →
Sources & verification
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