A shader that reduces vertex count

Hi,

I am working on a golf project and have a very highres detailed mesh of the terrain with thousands of vertices.
Now I am looking for a shader that reduces the vertices that are far away from the camera:

I already have extensively tested the DX11 Tesselation shaders delivered with Unity but they do not fit into my
workflow: I need a shader that works vice versa to the tessalation shaders:

Standard shaders have a lowres mesh and add vertices.
I have a highres mesh and need vertices...

A shader that reduces vertex count