What constitutes "the lights delineating the runway"?
Presumably it's your runway lighting (edge lights, such as HIRL, MIRL, etc, plus runway end identifier lights - REIL), centerline lights, and touchdown zone lights only, because being able to see the nearest approach light miles away isn't helpful if, by the time I'm at 200' half a mile from the runway (and past that outer-most approach light), I'm inside a dense fog bank with an RVR of 600 feet.

That said, it's a much more common case where the RVR at the runway (where it's measured) is about the same as the in-flight visibility farther out on final, so with an RVR of 4000' you can expect to see the threshold at typical Cat I ILS minimums of 200' AGL (okay, ATDZE for the pedantic &amp; precise), but at 1800 RVR at the same point, you expect to see approach lights but little else.