This is what I found:

1. Occhio: Apertura circolare praticata su una cupola o sulle facciate di una chiesa. VETRO A DISCO O "RULLO". Dal latino oculus. Definiti così in aree esterne a quella veneziana. (http://flaviofuga.free.fr/dx/glossario.htm)

2. Window glass was invented in the 12th century. In 1330, window glass was produced using crown glass or bull's eye glass production methods.

Window glass dates back to the gothic era of the 12th century. In 1330, a glassmaker in Rouen (France) developed a process for the production of CROWN GLASS, which is also known as BULL'S EYE GLASS. In this process, a bowl-shaped piece of glass (bullion) is spun into a flat disk by centrifugal force. Only the centre piece, which is around 10-15 cm in size, is used as window glass. (http://www.bvglas.de/en/the-material/history-development/)

3. Rulli: Known in Venetian as rùi, these were flat discs of glass, used for windows in the late Middle Ages and the Renaissance. During the 19th century they were made at Murano in polichromatic filigree, for ornamental purpose and using bright colours. They were also called ruodi (1405) or ruoi (1417) and vessighette. (http://www.barovier.com/en/azienda/vocabolario/)

4. .. We are told that 'A corresponding diminuitiveness characterized Venetian window glass which was apparently made by the spinning method, their RULLI or RUI being little panes of thick green glass called OCCHI DI BO or bull's eyes and very like the bullions of crown tables... (http://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=...