However, a small magnitude or intermittent strabismus can easily be missed upon casual observation. In any case, an eye care professional can conduct various tests, such as cover testing, to determine the full extent of the strabismus. Symptoms of strabismus include double vision and/or eye strain. To avoid double vision, the brain may adapt by ignoring one eye. In this case, often no noticeable symptoms are seen other than a minor loss of depth perception.
About trade unions. Trade unions are groups of employees who join together to maintain and improve their conditions of employment. The typical activities of a trade union include providing assistance and services to their members, collectively bargaining for better pay and conditions for all workers, working to improve the quality of public services, political campaigning and industrial action.
Legal Definition of labor union. : a labor organization usually consisting of workers of the same trade that is formed for the purpose of advancing its members' interests (as through collective bargaining) in respect to wages, benefits, and working conditions â see also craft union, bargaining unit.