If you haven't played Kuku Kube yet, go take it for a spin.
The game has the player identifying the differently colored square in an array of very similarly colored squares. It starts off quite easy, but grows in complexity with each successful identification.
Here, for example, is the first puzzle. The differently shaded square is pretty easy to spot.As you advance through the game, however, the squares multiply and the colors become more and more similar. Where's the differently colored square below, 25 matches into the game? The game is great, addictive fun, especially on a mobile device, but we can't help wondering what it's doing to our eyes. You stare so hard, focusing and unfocusing, accidentally crossing, willing the different square to appear... and yeah, at the end of all that, your eyeballs hurt. (Not unlike they did after you stared at #TheDress for three hours, or those magic eye pictures as a kid.)
So we called some experts to figure out if this game is slowly ruining our retinas.
Dr. Joel Schuman of the UPMC Eye Center says that the mechanics of the game—finding a close-but-different color amongst a sea of identical ones—will not harm your vision, but it might give you a headache:
Viewing colors, patterns, and other material at a safe level of brightness cannot hurt your eyes. That is, it cannot do any permanent damage. That does not mean that you cannot get headaches and eye discomfort from excessive viewing of visually taxing materials, but this will not injure your eyes.
Basically, the pain might not hurt your eyes, but you can experience some anguish.
We also spoke to Dr. Edward Chang, of the same institution, who said "it's kind of not good to stare at screens all the time. We're starting to see that that leads to more eye tiredness, and young people get nearsighted by always looking at something up close."
The technical term for what's at work in Kuku Kube is "contrast sensitivity," or being able to distinguish a shade of color as different from another. There is a valid ophthalmological test for this: Dr. Schuman says one's retina structure and brain function are what make someone good or bad at this. You could take that test... or you could keep playing Kuku Kube.
TL;DR: Go ahead and keep on finding shaded squares and staring at dresses, but maybe do so while holding your device an appropriate distance away from your face.
Screengrab via Kuku Kube