It seems safe to assume that the same percentages apply to photographers in general, including travel photographers, and those on vacation.
Unfortunately, many photographers who wear glasses seem to have difficulty focusing their DSLRs and composing their images due to their inability to see the image fully in their camera's viewfinder, “edge to edge.”
Fortunately, for most photographers who wear glasses, there are both equipment solutions and techniques to help with focusing and image composition.
We need to start with the photographer's glasses. Prescription lens glasses are either single-focus or multiple-focus. Multiple-focus lenses can be bifocals, trifocals, and progressive lenses. Of these, the most difficult to use while photographing are trifocals and progressive lenses.