Let’s get physical with web content.

Whatever you post on your site, the reader sees. Sure, we all know that. But consider—your reader’s eyes do the work: Find the data, register the data, shoot the data to the brain.

What if the eyes can’t find the message? What if tracking that elusive message fatigues the reader? They’ll click and they’ll be gone.

Make your web content literally easy for your readers’ eyes!

• Line length matters. On a long line, it’s difficult for our eyes to swing back and find the beginning of the next line. On a short line, when the end arrives abruptly, our eyes continue beyond the end, then have to swing back. Lines either too long or too short are tiring on the eyes; they slow down reading time and impede retention of the information. Instead, keep your line lengths close to 39 characters; that’s an alphabet-and-a-half, which gives a readable length line at any type size.

• Don’t center the text. Center headings if you must, but never center paragraph text. Our eyes automatically snap back to the starting margin, and those of us who use European languages intuitively seek a left margin. If the text is centered, you’re demanding that the reader’s eyes search for the starting point for each line. Sure, it takes barely seconds, but it’s tiring, and you can bet the reader is going to notice the difficulty. He’ll blame you, not his eyes! You might think centered text is attractive. But do you want people to think your content is pretty or do you want people to understand it? Instead, use left justified margins.

• Avoid bright colors. There are two problems with bright colors: The colored text draws the eye’s attention, but is rarely as legible as is regular text. So when the reader arrives at the word, he has to work to discern what the words say. Yet, while the reader is scanning through the rest of the page, the bright text remains in her peripheral vision, demanding attention. Don’t distract your reader. Instead, use bold text where you need emphasis.

Eye fatigue can be subtle, and the annoyance of it can be subconscious. A reader might pinpoint the problem (”Centered text, bleech!”) or he might not—he’ll just recognize that he wants to leave your web site. That’s not the message you want to deliver.