Mass. Gen. Laws ch. 160, § 178: Eye examinations

Section 178. A railroad corporation shall not employ any person or keep him in its employ in a position requiring the employee to distinguish form or color signals, unless he has been examined for color blindness or other defective sight by a competent person employed by the corporation and has received a certificate that he is not disqualified for such position by color blindness or other defective sight. A railroad corporation which violates this section shall forfeit one hundred dollars.