Review of periodic payments

(1) Any periodic payment payable under this Act either under an agreement between the parties or under an order of a court may be reviewed by a court on the application either of the employer or the workman if, (a) where the review takes place more than six months after the accident, it is claimed and proved that, had the workman remained uninjured and continued in the same class of employment as that in which he was employed at the date of the accident his average monthly earnings during the twelve months immediately preceding the review would, as a result of fluctuations in the rates of remuneration, have been greater or less by more than twenty per cent than his average monthly earnings during the twelve months previous to the accident (or if the periodic payment has been previously varied on a review during the twelve months previous to that review or the last of such reviews), the periodic payment shall be varied so as to make it such as it would have been if the rates of remuneration obtaining during the twelve months previous to the review had obtained during the twelve months previous to the accident; (b) there has been a change in the condition of the workman, in which case the application shall be accompanied by the certificate of a medical practitioner, or subject to regulations made under this Act, an application made without the certificate. (2) Any periodic payment may, on review under this section, subject to the other provisions of this Act, be continued, increased, decreased or ended, or if the incapacity is found to have resulted in permanent incapacity, be converted to the lump sum to which the workman is entitled.