I'm designing an illness found in a set group of people. Its effects worsen over time. They suffer from various issues such as nose and mouth bleeding, along with some form of anemia, lingering tiredness, dizziness, and vision blur. The intensity of the symptoms varies based on the stage of illness. Symptoms go from a light nose bleeding you could hide in your handkerchief, to as severe as spitting your arteries out while losing consciousness, leading eventually to death. This is not a nice illness, as you can guess. The time between first symptoms and death is about several years.
The symptoms described above are relatively easy to find and explain and have more or less real-world inspirations. I have (I think) a believable, not set-in-stone solution so far: some toxins are generated by the body and, mixed into the blood system, reduce blood pressure and efficiency, eventually breaking the more fragile blood tissues and leading to the aforementioned effects.
Still, while imagining it, I wanted to add something very peculiar that is only found in this illness. And you guessed it, it's turning one's eyes green. I could wave the reason behind it away, saying "it's magic science!", however I'd like to know if there could be a relatively plausible explanation before doing such hand-waving. It could also help me if I wanted to explain the inner details later on.
About eyes' color shift
Here are some details on this peculiar symptom :
- It starts to appear at a mid-level of the illness. At approximately the same time, you start to spit blood, and have light to medium dizziness.
- The color change can affect the iris or/and the "white" part of the eye. In order of preference, I would like the two, then the white part only, then the iris only.
- It should not change the color perception (you don't see green or everything but green, and you don't become blind either).
- The skin color doesn't really change, although slight changes are accepted. Indeed, since the skin becomes paler from anemia, it may be easier to see the toxin or whatever is causing that.
- The change comes gradually as the illness progresses.
- The effects can be reversed if the person is cured. Same as the above point, the reversal can be gradual.
- At a severe stage, I wish the color to be as close as possible to a deep, "Forest Green". If not possible, another deep green or "near cyan" one. I'd rather avoid yellowish or pale colors.
The most important thing I'm looking for is the biological process that would alter one's eyes. In case you happen to have a scientifically plausible explanation covering all of the processes, that's very nice and sure worth lots of points, but not 100% compulsory. Here are some additional goals, especially if you try to come up with a general solution:
- The reaction should not cause alone the death of the person. E.g. : You find a solution needing the heart's cells, but the person should not have a heart-attack afterwards.
- Kind of like the above point, you should try to keep the other symptoms intact. Nicer if you can avoid adding new ones too, even though it's cool if you can make them correlate to each other!
And last but not least, the simpler explanation, the better. I'd like to avoid drowning my world's explorers with a convoluted solution composed of 10 successive processes. Also, it's because I'm unfortunately severely held back by my lack of medical knowledge on this one. So please bear with me :).
As a similar real-world case, you may have heard of jaundice, which turns eyes yellow. I don't know the exact process behind it, and worse, it doesn't give a clean green color, and it affects skin as well. I also heard of traumas causing color shifts, as well as rare genetical anomalies (Fuchs syndrome, I guess?). However, no source I could find explained the exact processes involved, which would allow me to reuse them for my illness. Also, these health issues are more likely to remove the color (becoming "greyish") than modifying it, as far as I understood.
Hence my question, how can an illness make one's eyes turn green?