Punctuation marks and letters such as “W” can make the left or right edges of a column appear to be misaligned. Optical Margin Alignment controls whether punctuation marks (such as periods, commas, quotation marks, and dashes) and edges of letters (such as W and A) hang outside the text margins, so that the type looks aligned.
To turn off Optical Margin Alignment for an individual paragraph, choose Ignore Optical Margin from the Paragraph panel menu or Control panel menu.