Three Eyed Deities | Protector Deities: Traditions & Schools
There is a prevalent myth concerning Eastern deities or gods that have three eyes - two regular and a third eye at the center of the forehead. The myth with regard to Buddhist iconography and Himalayan style art is that any deity with three eyes means that the deity is enlightened and on the same level as a Buddha.
For various Hindu artistic traditions the third eye, as it is called, appears horizontal like a standard appearing eye. In Himalayan style art and the iconography of Buddhists the third eye is horizontal as if a copy or duplicate of the left eye was turned and made vertical with the brow of the eye turned to the right side of the face and the bottom of the eye turned to the left side of the face. This third eye is a type of wisdom eye and the left side of the body is the wisdom side and therefore a third eye should reflect the wisdom side of the body - and there follows the thinking.
For Tibetan Buddhist this idea partially comes out of the distinction between 'worldly deities' and 'wisdom deities.' Buddhas and their emanations are considered enlightened wisdom deities. All other deities are considered worldly and not fully enlightened.
Within the Tibetan Buddhist pantheon there are hundreds of wisdom deities and not all of them have three eyes. Figures with three eyes are generally described as semi-peaceful semi-wrathful or wrathful in appearance. Most peaceful wisdom deities have only two eyes.
Of the dozens, or many dozens, of depictions of worldly deities, almost all of the wrathful worldly deities have three eyes. Most of the peaceful worldly deities have two eyes. Examples of the worldly deities with two eyes are the Drala class (Warrior Appearance), along with subjects such as the Four Guardian Kings, Tseringma and her sisters, Ling Gesar, Achi Chokyi Drolma and others. Wrathful worldly deities with three eyes are by far the larger category with most of the Tibetan Buddhist worldly protectors included such as Pehar, Tsiu Marpo, Dorje Setrab, Dorje Ta'og, Dorje Shugden, Rahula, and most of the mountain gods and deities.
In conclusion, what can be said is that whether or not a deity has three eyes depends primarily on which of the three classes of general appearance a deity is represented in:  peaceful,  semi-peaceful semi-wrathful, or  wrathful. A deity having two eyes or three eyes has nothing to do with being a worldly or enlightened deity.
Jeff Watt 8-2013