maybe if you zone out a lot you start seing things in the real world that are not there =P...as in seing the invisible in the visible. now this is too
* O.o mehem
maybe it's not a matter of sight deterioration but more of that absence in your eyes that you keep even after you stop the dreaming.
The best way to remedy from this is to let yourself venture in unformiliar places ( taking walks (not sleepwalks) around the city or a forrest if u are lucky) and just looking around and getting lost in what you see ( it has to be during daytime). It was for me the most effective form of "meditation" and at least that way you wont be zoning out from the world but from yourself.