Doesn't a search engine consider that the text may not be indexed as its size is 0 ?
Since that was at one time a popular blackhat technique for spamming search engines, I can't say they don't react at all to that (I still haven't figured out how, since the spiders themselves do not look at the CSS sheet at all).
So far as I know it would be indexed, but again, sighted users without the image can't read a 0px font size : ) Lindsay method has that problem.
Here's what you want to do with any webpage you've built:
View it with CSS on and images off. This is a user with a slow connection or a device they've turned images off so they don't spend 30 minutes loading your page.
A "typical" screen reader user with a non-ancient reader will get your page mostly like it is with CSS and images off, except they can tell the semantics of the page (headers, lists, tables, forms, links and non-links), and display: none and visibility: hidden are honoured by many readers (so that's why people use negative text-indent: this is still read out by screen readers fine).