Los Oko son criaturas que salen de un órgano de la espalda de un Ustanak. Parecidos a insectos, su forma errática de volar recuerda a la de un murciélago. "Oko" deriva del término serbio que significa "ojo".
Como su nombre indica, son los ojos de los Ustanak, que tienen problemas de visión, pero lo curioso es que usan ondas ultrasónicas para rastrear a sus presas. Comparten sus órganos sensitivos con el Ustanak y cuando localizan a su objetivo emiten una luz y baten sus alas de una forma que solo el Ustanak es capaz de detectar (se desconocen los detalles de este proceso). Sus ondas ultrasónicas no pueden atravesar paredes u otras barreras. Los Oko no son muy útiles en combate y además es bastante sencillo destruir sus frágiles cuerpos.
Oko are creatures that are released from an organ on Ustanak's back. Insect-like in appearance, their erratic flight patterns are more indicative of bats. Oko is derived from the Serbian word for "eye."
As their namesake implies, they act as the eyes for the visually impaired Ustanak, but ironically rely on ultrasonic waves to track their prey. Their sense organs are shared with Ustanak, and when a target is found, they emit a flash and flap their wings at a level only Ustanak can detect. (The mechanism behind this shared sensory perception is unknown.) Their ultrasonic waves cannot pass through walls and other barriers.
The Oko serve no function in combat, and their fragile bodies are quite easy to destroy.
Below is a memo written by a member of Neo-Umbrella when the Oko were released.
There is a high probability that Jake Muller is in a cave at site D24. We will have Ustanak wait here, but have Oko released and positioned at multiple sites in order to increase chances of apprehension. We've equipped Ustanak with new weapons, so hopefully he will be able to at least bring back a piece of Jake. All we need is some fresh blood.
But it would be great to have that woman he's with brought back alive. She looks good enough to eat. I bet she'd make a great sound under the knife. I'm getting excited just thinking about it. I can't wait to slide my scalpel across her creamy, snow-white skin, cut it open and take a long look at the inside.