With a digital SLR camera, the diopter of the viewfinder can be optimally adjusted for the photographer's own vision. Approximately 90%of all eyeglass wearers then get along just fine without glasses. However, purchasing a so-called correction lens is really only worthwhile if your vision is strongly impaired – by a diopter greater than 6. The correction lens is screwed onto the viewfinder and enables you to see clearly through it without glasses.
Many digital SLR cameras are also equipped with a LiveView function. The rear display shows directly what the digital sensor sees and what is saved as a photo when the shutter button is pressed. For a final check that the picture is in focus, you can zoom in on the subject with the magnification function. This ensures you that you have photographed the subject perfectly. Many compact and mirrorless system cameras have only such a display for viewing the subject. In bright sunlight, however, these displays are at a significant disadvantage in comparison to a viewfinder. And only the photographer with a viewfinder will have a clear and glare-free view through the lens.
Those with presbyopia have a real advantage when photographing without glasses. It's true they can no longer see close-up very well and have to hold the newspaper as far away as possible in order to be able to read it. However, since the refractive power of the viewfinder is calibrated so that objects at a distance of 3 feet are in focus, the sight problem is rectified. You can see clearly and sharply and there is nothing to prevent you from taking a great picture.