Glasses mode is a buffer-local minor mode that makes it easier to read mixed-case (or “CamelCase”) symbols like ‘unReadableSymbol’, by altering how they are displayed. By default, it displays extra underscores between each lower-case letter and the following capital letter. This does not alter the buffer text, only how it is displayed.
To toggle Glasses mode, type M-x glasses-mode (see Minor Modes). When Glasses mode is enabled, the minor mode indicator ‘o^o’ appears in the mode line. For more information about Glasses mode, type C-h P glasses <RET>.