At the threshold of this opinion, we emphasize that there was no appeal by defendants or plaintiff from the full Commis*510sion’s award of permanent partial disability as provided for in G.S. 97-30. Therefore, this portion of the case is not before us, and that award remains in full force and effect.
We approve and adopt as our own the well-reasoned and well-documented decision of the unanimous panel of the Court of Appeals. However, we deem it necessary to consider and decide two points which were not considered in the decision of the Court of Appeals.
 The Court of Appeals failed to address the question of whether application of the 1978 version of G.S. 97-29 to the facts of the case before us constituted an unconstitutional retroactive application of substantive law.
Defendants argue that when plaintiff suffered “a diminished capacity to earn money” in 1970, his claim vested substantively and his employer was exposed to liability at that time. Defendants therefore contend that to apply the 1978 statute would interfere with vested rights and liabilities so as to contravene Article I, Section 16, of the North Carolina Constitution1 and Article I, Section 10, of the United States Constitution. We do not agree.
It must be first borne in mind that there is nothing before this Court relating to plaintiff’s entitlement under G.S. 97-30 to permanent partial disability compensation for the period 1970 to 1978. The sole question before us in deciding this assignment of error is whether plaintiff’s claim for permanent total disability amounted to a retroactive application of the 1978 version of G.S. 97-29. (1973 N.C. Sess. Laws Ch. 1308, §§ 1, 2). In our opinion, Wood v. Stevens & Co., 297 N.C. 636, 256 S.E. 2d 692 (1979), is dispositive of this question and answers it adversely to defendants’ contention. In Wood Chief Justice Sharp speaking for a unanimous Court (Justice Brock taking no part in the consideration or decision of the case) stated:
*511The proper question for consideration is not whether the amendment affects some imagined obligation of contract but rather whether it interferes with vested rights and liabilities. As we observed in Booker v. Medical Center, a statute is not unconstitutionally retroactive merely because it operates on facts which were in existence before its enactment. 297 N.C. at 467, 256 S.E. 2d at 195. See in accord, Frisbie v. Sunshine Mining Co., 93 Idaho 169, 457 P. 2d 408 (1969); Tennessee Insurance Guaranty Association v. Pack, 517 S.W. 2d 526 (Tenn. 1974); Sizemore v. State Workmen’s Compensation Commissioner, 219 S.E. 2d 912 (W.Va. 1975). Instead, a statute is im-permissibly retrospective only when it interferes with rights which had vested or liabilities which had accrued prior to its passage. Spencer v. Motor Co., 236 N.C. 239, 72 S.E. 2d 598 (1952); Wilson v. Anderson, 232 N.C. 212, 59 S.E. 2d 836 (1950); B-C Remedy Co. v. Unemployment Compensation Commission, 226 N.C. 52, 36 S.E. 2d 733 (1946).
Id. at 650, 256 S.E. 2d at 701.
All of the evidence in this record discloses that plaintiff did not become totally disabled until 1978. Thus, no right to recover for permanent total disability vested in plaintiff until after the enactment of the 1978 version of G.S. 97-29. No possible liability accrued to defendants as a result of plaintiffs permanent total disability until after the enactment and effective date of the 1973 revision of G.S. 97-29.
We therefore hold that application of the 1978 version of G.S.. 97-29 to the facts in instant case did not constitute an unconstitutional application of substantive law.
 The other question which the Court of Appeals failed to address was whether the Industrial Commission erred in limiting its award of medical expenses in conjunction with the permanent partial award to 300 weeks.
The Commission determined that plaintiff’s partial incapacity and entitlement for an award for medical expenses began in 1970. Therefore, consistent with the decision of the Court of Appeals, the award of medical expenses for the period of partial disability must be governed by the pertinent statutes in effect in the year *5121970. The full Commission’s award in instant case made no reference to the statute under which it made its award. In 1970 G.S. 97-25 and G.S. 97-59 each contained provisions applicable to an employee’s entitlement to an award for medical expenses.
G.S. 97-25 is the more general of the two statutes and was first enacted as a part of the original North Carolina Workmen’s2 Compensation Act. 1929 N.C. Sess. Laws Ch. 120. The original act made no provisions for occupational diseases but applied only to injuries by accident. The original provisions of G.S. 97-25 limited allowable medical expenses to ten weeks for treatment “required to effect a cure or give relief and for such additional time as in the judgment of the Commission will tend to lessen the period of disability . . . .”
G.S. 97-59 was enacted in 1935 when the provisions of the Workers’ Compensation Act were revised so as to extend coverage for victims of occupational diseases. In 1970 that statute specifically provided:
In the event of disability from an occupational disease, the employer shall provide reasonable medical and/or other treatment for such time as in the judgment of the Industrial Commission will tend to lessen the period of disability or provide needed relief .... [Emphasis added.]
We now turn to the question of which of the statutes is applicable to instant facts.
G.S. 97-25 applies generally to awards of medical benefits under the Workers’ Compensation Act. G.S. 97-59, the later enacted statute, applies specifically to awards of medical benefits in cases involving occupational disease.
Where one statute deals with a subject in general terms and another statute deals with a part of the same subject in detail, the specific statute will be construed as controlling, unless it appears that the Legislature intended to make the general act controlling. This is especially so when the specific act is later in point of time.
We find nothing indicating that the Legislature did not intend that the specific latter statute control. We therefore hold that G.S. 97-59 is applicable to the facts of this case.
The latter specific statute, G.S. 97-59, differs from the former, G.S. 97-25, in that it states two grounds upon which the Commission shall extend medical benefits. These grounds are stated in the disjunctive so that if either is found to exist by the Commission, an award for medical benefits must be made. The ground pertinent to this appeal is a finding that the treatment would “tend to provide needed relief.” The Commission in its finding of fact number six found “that medical treatment will be necessary for plaintiffs lifetime and will provide plaintiff with needed relief, though treatment will not reverse the damage to the lungs which has become permanent, but will only serve to prevent further damage.”
This finding was supported by competent evidence and is therefore conclusive. Inscoe v. DeRose Industries, Inc., 292 N.C. 210, 232 S.E. 2d 449 (1977). Such a finding mandates an award of medical expenses as long as the treatment provides needed relief. Even so, the Commission limited its award of medical expenses to 300 weeks. We are unable to find anything in the Workers’ Compensation Act which permits the Commission to limit the award of medical expenses under G.S. 97-59 to the period of time in which disability is paid. Upon finding that the treatment would provide needed relief, it was not necessary under G.S. 97-59 for the Commission to determine that such treatment would also lessen the period of disability.
We therefore hold that plaintiff was entitled to an award of medical expenses beginning in 1970 when the Commission found that his partial disability began and extending so long as the treatment provided “needed relief.” Of course, when plaintiff became totally disabled in 1978, he at that time became entitled to medical benefits under the provisions of G.S. 97-29.
We note that G.S. 97-59 requires that “all such treatment shall be first authorized by the Industrial Commission after consulting with the Advisory Medical Commission.” Obviously, strict *514adherence to this proviso would result in an absurdity in this case by denying plaintiff medical expenses for treatment of his undiagnosed occupational disease because he failed to get prior approval for the treatments. Plaintiff had no reason to seek approval until his condition had been diagnosed as a compensable occupational disease.
In Taylor v. Stevens & Co., 300 N.C. 94, 265 S.E. 2d 144 (1980), we find a similar situation. There we stated, “It is . . . clear that our Legislature never intended that a claimant for workers’ compensation benefits would have to make a correct medical diagnosis of his own condition prior to notification by other medical authority of his disease in order to timely make his claim.” Although Taylor was concerned with a claim for disability compensation rather than a claim for medical expenses, we believe that the same analysis obtains. The Commission may still consult with the Advisory Medical Committee as to the reasonableness of the cost of the treatment. We therefore hold that the requirement in G.S. 97-59 of prior approval of medical treatment applies only in cases where it is reasonably practicable to seek such prior approval. We note in passing that the present version of G.S. 97-59 omits the requirement of prior authorization and merely requires that medical bills be approved by the Commission. 1981 N.C. Sess. Laws Ch. 339.
In its opinion and award, the Industrical Commission’s Conclusion of Law number three provides:
3. For reasonable medical and/or [sic] treatment, solely of such a nature as to tend to lessen plaintiff’s period of disability or to provide plaintiff needed relief from his occupational disease and incurred during the 300-week period beginning 1 January 1970, employer is obligated to bear the cost thereof. [Emphasis supplied.]
For the reasons stated above, we hold that the 300-week limitation must be deleted from the opinion and award.
The decision of the Court of Appeals is modified and affirmed, and this cause is remanded to the Court of Appeals with direction that it be returned to the Industrial Commission for entry of award in accordance with the opinion of the Court of Appeals with the sole modification that the limitation contained in *515Conclusion of Law number three be deleted so that the amended award will — subject to authorization by the Commission after consultation with the Advisory Medical Committee — allow plaintiff to recover all medical expenses incurred between 1 January 1970 and the date in 1978 when plaintiff is found by the Commission to have become totally incapacitated.
Modified and affirmed.