We have previously discussed several ways in which poor typography and design (reverse type, weird typefaces, italics, and all caps) can make your text difficult to read. Another way is line length: too few or two many characters per line can cause eye strain. A comfortable range is 50 to 75 characters per line.
To help prevent eye strain while you are writing and editing drafts, make sure that the type size and line width in your normal word-processing template produce an average somewhere between 50 and 75 characters per line. For example, my normal template produces an average of 53.
This may sound like a small matter, but if you do a lot of writing and editing (for example, I average four to six hours per day), the effect on your eye muscles can be significant.
You may or may not be in a position to affect the finished appearance of the words you write. Your company’s designers or your clients’ designers may or may not be amenable to outside advice, and they may or may not be obliged to conform to pre-established templates or other corporate standards anyway. But if you do have some influence, you may wish to advise the designers on line length.
The Takeaway: Too few or two many characters per line can cause eye strain; 50 to 75 characters per line is a comfortable range.