Hi,
here, you'll find more infos...
Jar-ops 1 Subpart E, appendix 1 to jar-ops 1.430
para "g"
Visual Approach, An operator shall not use an RVR of less than 800m for a visual approach.
If you 're interested to get all that stuff..here's the link>>
http://www.jaa.nl/publications/jars/jar-ops-1.pdf
You can go straight to page 118..
rgds