Red-eye

Red-eye was a disease found amongst enslaved Ood on their homeworld of the Ood Sphere. Its symptoms were bright red eyes, rabid temperment and anti-Human sentiment.

It was most commonly caused by having no communications to the third brain. This caused the brain inside the Oods head and the brain in the Oods hands to fight or argue. This happened when humans modified the Ood with the translation orb because they also inslaved the third brain in a anti-telepathy circle, hence the saying "The circle must be broken". (DW: Planet of the Ood)

It may also have been caused by the subconscious of the Ood Brain reemerging amongst the Ood after 200 years of slavery and the sabotage of Ood Operations's systems by the Friends of the Ood. However, similar symptoms occured in the Ood serving the Walker Expedition on Krop Tor. It would later lead to the Battle of the Ood Sphere in 4126 and the freedom of the Ood. (DW: Planet of the Ood)

The Ood once again had red eye (DW: The End of Time) but it was not threatening unlike The Doctor's last two incounters to the Ood. This time they only saw the events of the End of Time

Other Cases of Red-Eye

It is thought that The Beast made the Ood have the Red-Eye effect when he took over them on the planet Krop Tor in the year 43K2.1. (DW:The Impossible Planet/The Satan Pit)