What's blind about the eponymous blind forest?

After finishing Ori and the Blind Forest, I still have no idea to what the blind part refers to in the games title. In what way is the forest blind?

As mentioned in the comments and in the beginning of the game Sein is introduced as the 'eyes' of the forest. But since Sein was separated from the spirit tree the forest lost it's light and 'sight'.

Players assume control of Ori, a white guardian spirit, and Sein, the "light and eyes" of the Forest's Spirit Tree.

Also the three elements of the forest also have a 'light', which is also a part of the process to restoring the 'sight' of the forest.

To restore the forest, Sein guides Ori to recover the light of three main elements supporting the balance of Nibel: Waters, Winds and Warmth.

Also at the end of the game:

Kuro takes Sein back to the Spirit Tree, which emits a flash of bright light that dissipates the fire and restores the forest.

Which also points toward Sein being the eyes of the forest while he/she is at the spirit tree.

Source: https://en.wikipedia.org/wiki/Ori_and_the_Blind_Forest

Edit: Spelling