Previously, the eye tracking glasses used a green LED for tracking eye movement. Noise from other light sources was interfering with the system. Plus, the green light shining in the user's eye was distracting. 

Trading the green LED for an IR LED solves both of these problems. To fully convert the system to IR tracking, we inserted an IR film to filter the eye tracking camera. Because the c270 camera is not very sensitive to IR light, we more than doubled the brightness of the IR LED by swapping the 200 Ohm chip resistor for a 75 Ohm chip resistor.