KAUGER, Justice.

The dispositive issue presented is whether a 1979 amendment of the Political Subdivision Tort Claims Act (Act) should be given retrospective effect thereby barring the claimant's action for wrongful death. The trial court held that the amendment operated retroactively, that the notice of claim requirement and the time-bar limitation of 51 O.S. 1981 § 156[ 51-156] were applicable, and entered summary judgment against the claimant. We find that because a substantive right was involved, the trial court erred in retroactive application of the statute.

On October 26, 1978, William Troy Hammons, (patient) the husband of Gracie I. Hammons, (appellant/widow), entered the Muskogee General Hospital, appellee/hospital, for surgery. He underwent a craniectomy for removal of a subdural hematoma. After surgery, he was placed in the intensive care ward. On October 29, 1978, Mrs. Hammons found her husband with his head wedged between the foot of the bed and the bed rail. Several corrective operations were performed to correct the damage, but the surgeries were unsuccessful, and the patient died on December 21, 1978. On December 17, 1980, the widow filed suit against Muskogee Medical Center Authority, d/b/a Muskogee General Hospital, (appellee). She alleged that the hospital was negligent in its medical care and treatment of her deceased husband. The hospital answered, denied the allegations of negligence, and filed a motion for summary judgment alleging lack of jurisdiction based on failure to give notice in compliance with the statute of limitations contained in 51 O.S. 1981 § 156[ 51-156]. The motion was sustained, and the widow has appealed timely.

THE 1979 AMENDMENT OF THE POLITICAL SUBDIVISION TORT CLAIMS ACT WHICH REDEFINED THE TERM "POLITICAL SUBDIVISION" DOES NOT BAR A WRONGFUL DEATH ACTION WHICH AROSE PRIOR TO AMENDMENT.

The Political Subdivision Tort Claims Act was adopted by our legislature as a conditional encroachment into the doctrine of sovereign immunity. It allows persons with claims against political entities to sue for redress after notice, and within prescribed time frames. At the time of decedent's death in 1978, the Act provided certain definitions. One term legislatively defined in the act was "political subdivision". The Act stated that for the purposes of the Act, a political subdivision is an incorporated city or town, a school district or a county and all of their institutions, instrumentalities or agencies. The Legislature defined "agency" as including "any Board, Commission, Committee, Department, or other instrumentality or entity designated to act in behalf of a political subdivision." Effective July 1, 1979, the definition of "political subdivision" was amended providing that the term political subdivision also means a public trust where a city, town, school district, or county is a named beneficiary.

In support of her request for reversal, the appellant contends that her cause of action accrued on the date of her husband's death, December 21, 1978, and that on that date the hospital was not included within the Act. The trial court based its ruling on the appellee's motion for summary judgment on a finding that the hospital was operating under a public trust authority, and that, therefore, the notice requirement of 51 O.S. 1981 § 156[ 51-156](D) was applicable.

At the time of the patient's death, a political subdivision within 51 O.S. 1978 Supp. § 152 [78-152](6) was either an incorporated city or town, a school district or county, and all their institutions, instrumentalities or agencies. A public trust which named a city, town, school district or county as beneficiary was not a political subdivision by statutory definition. The hospital filed an affidavit by its Administrator who testified that the hospital was a public trust, and that the City of Muskogee, Oklahoma, was its sole beneficiary. Attached to the affidavit was the trust indenture. Upon this uncontroverted evidence the trial court applied the 1979 amendment, found that the hospital was a political subdivision, and held that the action was filed untimely.

Prior to the 1979 legislative amendment, a municipal hospital which operated under a public trust authority, and not as an agent of a municipality, could not avail itself of the statutorily limited doctrine of sovereign immunity. As a general rule, a statute or its amendments will have only prospective effect unless it clearly provides otherwise. The revision of the statute to include the hospital within its protection was not a mere procedural provision. At issue is the widow's substantive right to bring an action against the hospital.

Article 5 § 54 of the Oklahoma Constitution precludes the application of the Political Subdivision Tort Claims Act to the facts in this case. The Constitution provides that the repeal of a statute shall not affect any accrued right. The accrual of a cause of action means the right to institute and maintain a suit. The proper test is to ascertain when the widow could first have maintained her action. The Constitution prohibits legislative disturbance of the existence of a cause of action from and after its inception. A person's failure to exercise a right statutorily provided therein, before the repeal or amendment of the statute, in no way affects or lessens the right. To apply the amendment retrospectively, would in effect abrogate the widow's cause of action for wrongful death and violate art. 23 § 7 which forbids elimination of the right to recover damages for injuries resulting in death. The trial court erred when it applied the 1979 statutory definition of the term political subdivision to a cause of action which accrued prior to the amendment.

The question of agency was not addressed in the order of summary judgment, nor do we make any determination today of that issue. The hospital has consistently argued, that from its inception, it was an agency of the City of Muskogee and acquired subsequently the status of a public trust. On remand, the question of agency should be resolved based on the relationship between the municipality and the hospital on the date of death of the patient. The initial question the trial court will confront is whether the hospital qualifies as an agency of Muskogee, Oklahoma. If the hospital is an agency of the municipality, the provisions of the Political Subdivision Tort Claims Act are applicable. If not, the controlling statute of limitations is the statute which governs wrongful death actions, 12 O.S. 1981 § 1053[ 12-1053](A).

REVERSED AND REMANDED.

DOOLIN, V.C.J., and HODGES, LAVENDER, HARGRAVE, OPALA, WILSON, JJ., concur.

SIMMS, C.J., concurs in result.

SUMMERS, J., disqualified.