Ohio Revised Code Title XLIX. Public Utilities § 4999.16

No railroad company shall contract to employ a person in a position which requires such person to distinguish form or color signals, unless within two years preceding such date he has been examined for color blindness, in the distinct colors in actual use by such company by a competent person employed and paid by such company, and has received a certificate that he is not disqualified for such position by color blindness in the colors used by the company. No such company shall fail to require such person to be re-examined at least once each two years at the expense of such company. This section does not prevent a railroad company from continuing in its employment an employee having defective sight when such defective sight can be fully remedied by the use of glasses or by other means satisfactory to the person making such examination. Whoever violates this section shall be fined one hundred dollars.