It should be noted that there is a difference in notation between eyeglass prescriptions and the markings on Nikon's (and most other) eyepiece diopters.
While both use "diopters" as their unit of measurement, they don't measure the same thing. Eyeglass prescriptions are marked with the strength of the lens itself. Eyepiece attachments are usually (always with Nikon) marked with the net total strength of the VF eyepiece lens plus the attachment.
Nikon's "blank" eyepiece attachment is plano glass (0d) yielding a system total of +0.5d (approx). Nikon's "0" attachment has an actual strength of -0.5d yielding a net system strength of 0d. With the "default" attachment the VF image appears to be 2 meters away, that is your eye must focus to 2m to focus on the image. With the "0" attachment, the VF image is projected at infinity and to see it clearly your eye must be able to see clearly at infinity.
If you intend to use the camera with your glasses on you should use a Nikon 0 attachment, as philcycles said in his post.