Step 1 : Introduction to the question "What are the holes in Swiss cheese called?"
...The gas-formed holes in certain types of cheeses, such as Swiss and Gouda cheeses, are "eyes." Cheese without holes is "blind." Microbes in the mix metabolize the nutrients and release carbon dioxide gas. This forms the eyes. The eyes are the large, round and oval openings formed from gas during the cheese-making process. Other types of cheeses, such as Colby, may have tiny mechanical openings that relate to the way the curds knit together when pressing the cheese into the mold. These small openings are not considered "eyes." Source: CheeseScience.org