What is the difference between lenses, the optical power of one of which is +2.5 diopters, and the other -2.5 diopters?

The optical power of the lens at +2.5 diopters means that the collecting lens is convex, the focal length of which is 1 / 2.5 = 0.4 m.
The optical power of the lens of -2.5 diopters means that the scattering lens is concave and the focus is imaginary, located at a distance of 0.4 m from the plane of symmetry of the lens.

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