Section 301(a.1) Nothing in this act shall require payment of compensation under clause (a) or (b) for any period during which the employee is incarcerated after a conviction or during which the employee is employed and receiving wages equal to or greater than the employee’s prior earnings. ((a.l) added June 24, 1996, P.L.350, No.57)
(a.2) (l) When an employee has received total disability compensation pursuant to clause (a) for a period of one hundred four weeks, unless otherwise agreed to, the employee shall be required to submit to a medical examination which shall be requested by the insurer within sixty days upon the expiration of the one hundred four weeks to determine the degree of impairment due to the compensable injury, if any. The degree of impairment shall be determined based upon an evaluation by a physician who is licensed in this Commonwealth, who is certified by an American Board of Medical Specialties approved board or its osteopathic equivalent and who is active in clinical practice for at least twenty hours per week, chosen by agreement of the parties, or as designated by the department, pursuant to the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment."
(2) If such determination results in an impairment rating that meets a threshold impairment rating that is equal to or greater than fifty per centum impairment under the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment," the employee shall be presumed to be totally disabled and shall continue to receive total disability compensation benefits under clause (a). If such determination results in an impairment rating less than fifty per centum impairment under the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment," the employee shall then receive partial disability benefits under clause (b): Provided, however, That no reduction shall be made until sixty days' notice of modification is given.
(3) Unless otherwise adjudicated or agreed to based upon a determination of earning power under clause (b)(2), the amount of compensation shall not be affected as a result of the change in disability status and shall remain the same. An insurer or employee may, at any time prior to or during the five hundred week period of partial disability, show that the employee’s earning power has changed.
(4) An employee may appeal the change to partial disability at any time during the five hundred-week period of partial disability; Provided, That there is a determination that the employee meets the threshold impairment rating that is equal to or greater than fifty per centum impairment under the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment."
(5) Total disability shall continue until it is adjudicated or agreed under clause (b) that total disability has ceased or the employee’s condition improves to an impairment rating that is less than fifty per centum of the degree of impairment defined under the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment."
(6) Upon request of the insurer, the employee shall submit to an independent medical examination in accordance with the provisions of section 314 to determine the status of impairment: Provided, however, That for purposes of this clause, the employee shall not be required to submit to more than two independent medical examinations under this clause during a twelve-month period.
(7) In no event shall the total number of weeks of partial disability exceed five hundred weeks for any injury or recurrence thereof, regardless of the changes in status in disability that may occur. In no event shall the total number of weeks of total disability exceed one hundred four weeks for any employee who does not meet a threshold impairment rating that is equal to or greater than fifty per centum impairment under the most recent edition of the American Medical Association "Guides to the Evaluation of Permanent Impairment" for any injury or recurrence thereof.
(8)(i) For purposes of this clause, the term "impairment" shall mean an anatomic or functional abnormality or loss that results from the compensable injury and is reasonably presumed to be permanent.
(ii) For purposes of this clause, the term "impairment rating" shall mean the percentage of permanent impairment of the whole body resulting from the compensable injury. The percentage rating for impairment under this clause shall represent only that impairment that is the result of the compensable injury and not for any preexisting work-related or non-work-related impairment.

((a.2 added June 24, 1996, P.~.350, No.57)