Optics in Japan

Doing some digging on line to find out when magnifying glasses were developed in Japan I came across this site:

http://www.antiquespectacles.com/topics/japanese/japanese_influence.htm

It looks like the first examples were introduced in 1551 and wider domestic production started around 1620. I have to wonder how long it took for the first daimyo to own a pair to think about what his preferred kodogu maker might be able to do with the new technology.