(a) In case of total disability adjudged to be permanent 80 percent of the injured employee's spendable weekly wages shall be paid to the employee during the continuance of the total disability. If a permanent partial disability award has been made before a permanent total disability determination, permanent total disability benefits must be reduced by the amount of the permanent partial disability award, adjusted for inflation, in a manner determined by the board. Loss of both hands, or both arms, or both feet, or both legs, or both eyes, or of any two of them, in the absence of conclusive proof to the contrary, constitutes permanent total disability. In all other cases permanent total disability is determined in accordance with the facts. In making this determination the market for the employee's services shall be
(1) area of residence;
(2) area of last employment;
(3) the state of residence; and
(4) the State of Alaska.
(b) Failure to achieve remunerative employability as defined in AS 23.30.041(r) does not, by itself, constitute permanent total disability.