aggravation only. (4) Where the degree of disablement of a disabled person has not, in the opinion of the Commissioner, reached a final and stationary condition, the disablement pension payable to that person shall be assessed on the degree of disablement as determined from time to time by the Commissioner after considering the report of a medical practitioner employed by the State, and such assessment shall be effective— (a) from the first day of the month immediately following that on which the medical practitioner examined the disabled person; and (b) for such period, being not less than six months, as the medical practitioner may fix in each particular case. 9 Date of accrual of disablement pension (1) Subject to subsection (2), where the degree of disablement of a disabled person has, in the opinion of the Commissioner, reached a final and stationary condition, the disablement pension shall be payable with effect from the 1st July, 1980: Provided that, where the disabled person has been discharged from his employment or is compelled as a result of his disablement to change his normal occupation or to follow a lower standard of occupation before the 1st January, 1982, his disablement pension shall be payable in accordance with the degree of disablement as assessed on or after the date of that discharge or compulsion. (2) Where the degree of disablement of a disabled person has not, in the opinion of the Commissioner, reached a final and stationary condition before the 1st January, 1982, the disablement pension— (a) shall be payable in accordance with the degree of disablement as assessed on or after the 1st January, 1982, with effect from the 1st July, 1980; and (b) shall be subject to variation or withdrawal according to the degree of disablement as assessed from time to time with effect from the date referred to in subsection (4) of section eight. 10 Commutation of disablement pension (1) Where— (a) the degree of disablement of a disabled person has been accepted by the Commissioner as having reached a final and stationary condition and— (i) the degree of disablement has been assessed at less than twenty per centum; or (ii) the disablement pension payable to the disabled person is less than three hundred dollars per annum; or (b) in the opinion of the Minister, the special circumstances of a disabled person so require it; the Minister may direct that the disablement pension be commuted at the appropriate rate set out in the Third Schedule: Provided that where the disabled person concerned notifies the Minister that he does not wish to have his pension commuted, the commutation shall not be made or, if made, shall be cancelled. (2) Notwithstanding the commutation of a pension in terms of subsection (1), if— (a) the degree of disablement of a disabled person deteriorates by five per centum or more of total disablement; or (b) the Commissioner allows an application in terms of subsection (6) of section seven; the disablement pension shall be adjusted accordingly and the Minister shall direct that— (i) the pension so adjusted be commuted in terms of subsection (1); or (ii) in addition to the pension already commuted and taking into account the adjustment made in terms of this section, the disabled person be paid such further pension as the Commissioner may determine. 11 Medical examination and treatment (1) A disabled person may be required by the Commissioner to undergo such