When taking photos, we mainly look through the viewfinder. The viewfinder is an element of the camera designed to visually determine the frame (the boundaries of the image of the object being shot). The photographer uses the viewfinder to compose the shot. There are two main types of viewfinder.
Optical Viewfinder (OVF) is found in DSLR cameras. The essence of a DSLR is that through a system of mirrors, prisms and lenses, light coming through the lens enters the viewfinder. The photographer sees the same as the camera lens. And at the moment of shooting, the mirror, directing the light into the viewfinder, rises, and the lens projects the image onto the camera sensor.
Electronic Viewfinder (EVF) is a design in which we look through an eyepiece at a small LCD or OLED display. Due to the absence of a mirror and a prism in the design, the electronic viewfinder is much more compact, and for this reason it is used in mirrorless cameras.
Shooting landscapes is both the search for new interesting places for shooting, and unusual angles, and tracking weather changes. In this case, the muscles of the eyeball are trained. I have noticed that when shooting landscapes, my vision sharpens somewhat. When taking photos, I use DSLR cameras. In DSLR cameras, sighting occurs through the OVF. We see a natural three-dimensional picture. Therefore, our eyes get tired less. In EVF we see a flat picture (image). In fact, we do not see any further than the EVF matrix. And our eyes get tired. Slow loss of vision occurs. The choice of a monitor for photo processing is best done after studying the most significant characteristics that affect the final result and fatigue.
P.S. Once I urgently had to photograph people. Only the Sony α7SIII mirrorless camera was at hand. Sighting throughout the entire survey mainly took place through the EVF. By the end of the shoot, my eyes were very tired.