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.
labor union labor unions plural a labor union is an organization that represents the rights and interests of workers to their employers for example in order to improve working conditions or wages am n count in brit use trade union