As used in this article, the term:

(1) "Merger of an injury with a preexisting permanent impairment" describes or means that:

(A) Had the preexisting permanent impairment not been present, the subsequent injury would not have occurred;

(B) The disability resulting from the subsequent injury in conjunction with the preexisting permanent impairment is materially, substantially, and cumulatively greater than that which would have resulted had the preexisting permanent impairment not been present, and the employer has been required to pay and has paid compensation for that greater disability; or

(C) Death would not have been accelerated had the preexisting permanent impairment not been present.

(2) "Permanent impairment" means any permanent condition due to previous injury, disease, or disorder which is, or is likely to be, a hindrance or obstacle to employment or to obtaining reemployment if the employee should become unemployed.