Heterochromia
Heterochromia is a medical condition where the irises are differently colored. There are two kinds: complete and partial. Partial heterochromia is where part of the iris is differently colored from the rest. Chris has complete heterochromia, where one eye is a different color from the other.
Chris claims that although his eyes were originally in high school[1] he contracted pink eye (conjunctivitis) in his right eye and the prescribed eye drops turned it green. His explanation is almost certainly incorrect - while some medications can cause heterochromia as a side effect, the simple antibiotic or antihistamine eye drops prescribed for conjunctivitis cannot.
It's more likely that the condition is hereditary. In school pictures taken while Chris was very young, close examination reveals that his eyes are different colors. Nevertheless, the pink eye story is one of his favorites when introducing himself to girls:
It is also a prominent, often exaggerated feature of his Mary Sue renditions. In reality, Chris's condition isn't particularly noticeable except upon close examination, and the less kind amongst us might presume that he only plays it up for want of any other endearing characteristics. According to eye witnesses (pun completely intended), Chris's eyes are indeed differently colored, but not to the degree Chris describes or draws:
| “ | Chris's eyes are very, VERY slightly different in color. It's nothing you would be able to notice unless he fucking points it out to you...or you just happen to notice small details like that. | ” |
| Emily | ||
A close examination of Chris's eyes seems to indicate that Chris's "green" eye is actually more of a hazel/greenish shade of blue rather than a distinctly green eye as Chris portrays. It should also be noted that, despite his insistence on pointing out that his eyes are different colors, Chris often mistakenly colors his right eye blue and his left eye green in his comics. Perhaps this is retardation, perhaps it is a symptom of studying himself in the mirror to memorize his appearance,[2] perhaps he doesn't pay too much attention while coloring to get the details right for his self-insertion, perhaps he just doesn't know his left from his right, or perhaps Chris himself really doesn't notice the difference between the colors of both of his eyes enough to get them accurately more than about 50% of the time.