Cat eyes - DimethylSulfate/drooldick GitHub Wiki

Cat eyes (also called glow eyes or evil eyes) are a symptom of cachaemia where their eyes reflect back some light. This is a vestige of how scientists would check for success uptake of the gene therapy, as the actual effects tended to take a long time to be measured. This is considered undesirable as about 0.5% of newly-infected cachaemites who develop cat eyes have a marked decrease in visual acuity. A small proportion become completely blind.

The function of the cachaemite cat eyes is very similar to the tapetum lucidum of many animals — increasing the amount of light available for better night vision, at the cost of slightly blurring the image. Cachaemites with cat eyes are also more likely to have visual photosensitivity. This combined with their tendency to develop rashes under UV light has made some cachaemites live a more nocturnal lifestyle.

Paradoxically, pregnant cachaemites are more likely to have children born blind from birth, but those who are not born blind tend to have slightly better visual acuity than those infected later in life. It is thought that a developing brain can better compensate for this structural difference if it is not too severe.

The naming of this condition can be a touchy subject, as some cultures who believe in literal evil eyes deeply fear cachaemites with this trait. Many cachaemites Licentia began self-associating with domestic cats in attempt to popularize the "cat eyes" idea over the "magical curse" idea. A side effect of this effort is that a cachaemite community in New Orleans was found to be responsible for 2,000 semi-feral cats wandering the neighborhood due to dozens of first-time owners not realizing how persistent an intact outdoor cat can be. In Licentia, cachaemite members of AthPro almost universally use those glowing cat eyes patches on their helmets or fatigues.

Variations

Cachaemites who were given gene therapy under medical supervision prior to 2011 almost always have cat eyes. Once concerns about the visual effects came to light, the therapy was tweaked to block this side effect, so more recent patients almost never have cat eyes. The C-virus which is spreading on its own, however, typically causes cat eyes.

Jang-mi (from both timelines) has a rare variation where only one eye is affected. She tends to call it her evil eye, and closes it when shooting. When she needs it closed for a long time, she will wear an eyepatch.

Although Gráinne was born blind, doctors specializing in cachaemites believe Zero's cachaemia is only a moderate contributing factor. She appears to instead be completely missing certain vital cells in her eyes. Nevertheless, she and her brother do have glow eyes, although the exact details of the structure is atypical. Eoin appears to have 20/20 vision, although it is hard to test him due to his tendency to have minor visual hallucinations. Síle is also known to have normal or near-normal vision based on how she moved and fought, although Daoirse has not elaborated on any of her children's biology.