From what we know ther are two forms of izanagi, the incomplete form and the complete form. Danzo's was the incomplete form whilst tobi's was the complete. In both cases the lost an eye, but it was the sharigan they lost. We can speculate that tobi who im 99.9% sure being an uchiha an having hashriama's dna was able to use the complete form of izanagi whilst danzo couldnt. After all its said to be an uchiha technique although from what we have read it requires hashirama/senju dna.
Now if sasuke was to get hashirama's dna and use izanagi, im not sure he wouldnt go blind due to having the ems which so to speak stops blind less, so this counters the effect of izanagi if used by an ems user. Logically speaking i dont believe sasuke would go blind if he used it, but kishi can decide otherwise.