(a) Subject to Subsection (b), an employer does not commit an unlawful employment practice by engaging in a practice that has a discriminatory effect and that would otherwise be prohibited by this chapter if the employer establishes that the practice:
(1) is not intentionally devised or operated to contravene the prohibitions of this chapter; and
(2) is justified by business necessity.
(b) An employer may not use a qualification standard, employment test, or other selection criterion based on an individual's uncorrected vision unless the standard, test, or criterion is consistent with business necessity and job-related for the position to which the standard, test, or criterion applies.