Va. Code Ann. § 58.1-3506.3

For purposes of this article, the term "permanently and totally disabled" means unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment or deformity which can be expected to result in death or can be expected to last for the duration of such person's life; however, a certification pursuant to 42 U.S.C. § 423 (d) by the Social Security Administration, so long as the person remains eligible for such Social Security benefits, shall be deemed to satisfy such definition in this section.