How to understand it
It is a component of the near prescription, not necessarily the final near SPH. The task and complete prescription matter.
An example
Teaching arithmetic: distance SPH −3.00 D plus ADD +2.00 D gives near sphere −1.00 D; other prescribed components must still be retained.
A common mix-up
ADD +2.00 does not mean everyone should buy a +2.00 ready-made reader.
See the idea in a full guide →
Sources & verification
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