Meditation - eyes open or closed

[Plenum]

Any opinions? Fruitfulness of each one? 

I remember reading in the Tibetan book of living and dying it is recommended to keep your eyes open. 

The physical world has a powerful ability to fill the senses, and flood the mind with data to process.  That data then has the ability to trigger thoughts.

Visual inputs, even more than aural ones, come to create in the brain what we conceive of as our 'reality'.

I think one of the aims of meditative practice is to explore and examine the world of consciousness, and while that visual tether is still open, the mind is connected to the outer physical space, and it is that which dictates the flow of thoughts.