Evolution of human colour vision opsins was increasing from 400 to 430. During this time, Ancestral Boreotherian had two long wave length opsins created by gene duplication, with one retaining the absolute max value of 560, equal to the ancestral value. This led to the creation of the modern human long wavelength sensitive, or red opsin. The other short wavelength sensitive opsin decreased its absolute max value to 530 and became the middle wavelength sensitive, or green-sensitive opsin. This occurred through mutations involving S180A, Y277F and T285A. The order that these mutations took place in the ancestral Boreotheria is currently not fully known. It is
Eye tracking designed optical sensor. The information is then analyzed to extract eye rotation from changes in reflections. Video-based eye trackers typically use the corneal reflection (the first Purkinje image) and the center of the pupil as features to track over time. A more sensitive type of eye-tracker, the dual-Purkinje eye tracker, uses reflections from the front of the cornea (first Purkinje image) and the back of the lens (fourth Purkinje image) as features to track. A still more sensitive method of tracking is to image features from inside the eye, such as the retinal blood vessels, and follow these features as