Correction, the optimal vision range is 60 squares, not 30. (I’m sure that was just a typo)
Maximum monster sight range is 50 squares, so yes, by default you can see 10 squares further than any monster.
Monsters are not affected by penalties (or bonuses) that reduce player sight range, like nearsightedness or being boomered (or nightvision). These conditions can cause an inversion where monsters can see you before you can see them, if you have a condition limiting sight range, be careful!
Monster sight range is affected by ambient light levels. In other words, light level from time of day and weather. They lose the same amount of range that the player does based on poor lighting, so if it’s dark and you can only see 40 squares, a monster that can normally see 50 squares can now only see 30. This means that if you can only see 10 squares due to low lighting, monsters can’t see you at all (unless you’re right next to them, everything that isn’t blinded can see things adjacent to them no matter the light level)
There is a VERY important caveat to this, which is light sources. If you are illuminated (for example by carrying an activated torch or flashlight), monsters can see you from up to their maximum sight range, walking around in the dark with a light source is extremely dangerous. To reverse this situation, you can illuminate a monster while staying in the dark yourself, for example by throwing a lit flashlight or flare at a zombie from outside its sight range.
There are currently no monsters with night vision, though there’s nothing keeping us from adding them. At close range however most monsters can detect you via hearing and/or scent.