Is it always necessary to close my eyes while meditating? -
Most, but not all, techniques and all stages of a particular technique, tend to require that you have your eyes closed. Some, on the other hand, specifically require you to have open eyes; still others leave the option to you.
Below is the Osho understanding about how closing the eyes facilitates going inside.
There is no naturally given way to go inwards, but it is not needed. If enough consciousness is gathered in, it will create its own way, just as water creates its own way – no map, no guidelines, just enough quantity and the water will start flowing towards an unknown sea. It has never heard about, knows nothing about, where it is going.
The same is true about consciousness. Enough consciousness gathered inside immediately makes a way upon which nobody has ever trodden, and starts moving inwards. Outward senses are closed; that’s what I mean when I say in your meditations to close your eyes, to leave the body completely behind...because all the senses are joined to the body. Just be a watcher of the mind, so the mind cannot take your energy outside. With body and mind both closed, energy gathers upon itself spontaneously and, at a certain point, it starts moving inwards. You don’t have to do anything except to close all the doors that lead you away from yourself.
It is one of the simplest things because you don’t have to do it. But just because of its simplicity, its obviousness, it has become difficult, the most difficult thing, because nobody can teach you; nobody can indicate to you where to move, how to move. The master can only create a situation in which the spontaneous movement of the energy will happen.
That’s what I call meditation. It is not your doing. You have to stop doing everything. It is your non-doing. The moment when you are not doing, all your energy that was involved in doing a thousand and one things is released. It gathers to a point where it starts flowing inwards, and the innermost center is not far away.