New measurements of the sky's blackness show galaxies only number in the hundreds of billions. How dark is the sky, and what does that tell us about the number of galaxies in the visible universe? Astronomers can estimate the total number of galaxies by counting everything visible in a Hubble deep
Not an expert on it, but I thought the overall estimation of the amount of dark-matter also depends on the amount of non-dark matter observed, but IDK.
Sounds like a good thought. I am no expert either.