Let me put it really simply. There is no 'third eye'. There are no horns on a rabbit. It is possible to construct an idea of 'third eye' just as it is possible to photoshop a rabbit with horns, but these are both conceptual constructs. The 'third eye' construct is typically a western construct/misunderstanding. So it is not like you can go to a doctor or even Tibetan lama and ask them to do something with this 'third eye' of yours. Here we are getting into new age fantasy about being able to open a third eye in order to access higher states of consciousness. It is a dangerous and misleading path to follow.
But then what about central channel and chakras and so on? It would also be a mistake to view them as biological phenomena. Why? Because we are giving them a size and location when infact they can be as big as the universe or as thin as a thread. If we are making them biological facts then we are getting into Lobsang Rampa fiction.
They are related to our energy but we shouldn't make anything of them. It all comes down to the teacher's instructions and to get a bit of knowledge about these things before been given the practice is very dangerous. I repeat that buddhists don't make objects. This is very important. It is misleading and dangerous to indulge fantasies in this way. Practicing Tsalung Tigle depends 100% on devotion. Can't get the fruit of the practice without devotion. Of course some practioners think they can get some knowledge and do things by themselves but it really isn't possible.
The Blessed One said:
"What is the All? Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All. Anyone who would say, 'Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range." Sabba Sutta.