It would be an understatement to suggest that the Miraluka are a rarity, many will go their entire lives without seeing a single one of these mysterious beings. The mystery enshrouding this race is a byproduct of their rarity, secrecy, and cultural mysticism. Miraluka are best known for their uncanny sensitivity to the Force, a trait that manifests itself in any and all who are among this rare breed.
The greatest Miralukan irony is the one found beneath the veils they wear, most often obfuscating their most unique characteristic. This being their eyes. Miraluka do not "see" in the conventional manner so many are accustomed to. Rather, they see through the Force; the eyes they are gifted with at birth are those of a seer.
The first (and only so far) encounter with the strange Miralukan race takes place in Star Wars: Knights of the Old Republic II - The Sith Lords. An apprentice and personal assassin to the fearsome Darth Nihilus, Visas Marr is sent to kill the Jedi Exile (aka the player). After being teased with multiple cutscenes, Visas Marr will appear in the Ebon Hawk after the completion of events on the first world the player visits after Telos IV. For purposes of clarification, it should be noted that the player has a choice of order between the following four planets to visit: Dantooine, Korriban, Nar Shaada, and Onderon (the journey to Onderon is comprised of both a trip to Onderon and her moon, Dxun).
After defeating Visas Marr, she will join the player's party. If you manage to gain her trust, over the course of the adventure, she will exponentially provide you with a firsthand account of the traits and history of her people. In doing so, the Miralukan's "Force Sight" is greatly elaborated on.
Whether their eyes are a blessing or a curse is up for debate; regardless, their inability to perceive the environment around them, in a more familiar sense, is supplemented by their acute perception of the Force. As described by Visas, it is as if the seer can witness the events of an entire galaxy, be it on a grand scale or microscopic level.
Alas, the best way to describe Force Sight is to see it yourself. As said above, there are a plethora of benefits should you accrue enough influence (see the Kotor II page for more information on the influence system) with Visas, as with all other companion characters. Visas will teach you this rare ability and you will be able to see the Force as a tangible entity, rather than the conceptual philosophy expressed prior to Kotor II.