(a) Any disability retiree who has not attained service retirement age may be required to submit current medical records annually until attaining service retirement age, by a physician or physicians designated by the board of trustees.
(b) Should any disability beneficiary who has not yet attained sixty (60) years of age refuse to submit to at least one (1) medical examination in any such year, and should such refusal continue for ninety (90) days after the records have been requested, such beneficiary's monthly retirement benefit may be suspended by the board of trustees.