I have noticed for years now that when I spend any more than about a minute reading something on the Memory Alpha website (a Star Trek wiki), I temporarily see horizontal lines in my vision that last a few minutes.

Does anyone know what it is on the website that is causing this side effect? It is annoying enough that I avoid that website whenever possible, although it is sometimes necessary to visit the site when answering questions on SciFi.SE.

I'm assuming that it is something in the background, but I'm not sure if it is a background color, an image, the text color, or some combination of those. If I can identify it, I might be able to set up a user stylesheet in my browser to filter it out.

I will add that I spend a lot of time on my computer, and that particular website is the only one I've ever noticed having that effect on me.


I expect it's an afterimage of the white lines on the black background. Like when you look at a lightbulb, and then close your eyes, you see a blob of light.

More precisely, it's called a physiological afterimage. It could be that the contrast of your monitor and the brightness are very high. In that case, the bright white text contrasts very strongly with the dark background.

If the brightness overall were very high, your iris would contract, to stop your retina from receiving more light than it can handle. In this case, however, the total amount of light is fine, but it's not distributed evenly, so some cells in your retina get very little light, and some get too much, causing the afterimage.

You can probably change to a different theme if you make an account at Memory Alpha.


There is a really useful bookmarklet that I use for websites with backgrounds that make them hard to read.

If you create a new bookmark on your toolbar and add this JavaScript to it, it resets any webpage to black text on a white background.

javascript:(function(){var newSS, styles='* { background: white ! important; color: black !important } :link, :link * { color: #0000EE !important } :visited, :visited * { color: #551A8B !important }'; if(document.createStyleSheet) { document.createStyleSheet(%22javascript:'%22+styles+%22'%22); } else { newSS=document.createElement('link'); newSS.rel='stylesheet'; newSS.href='data:text/css,'+escape(styles); document.getElementsByTagName(%22head%22)[0].appendChild(newSS); } })();

You can of course edit the CSS to any colour scheme you like.

Source: http://www.456bereastreet.com/archive/200608/light_text_on_dark_background_vs_readability/

Not exactly an answer to the question, but a way of getting around the issue of the horrible background.

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