1. Near-sightedness is a visual defect.
    近视是一个视力缺陷。

2. Primary school teachers use a lot of visual aids.
    小学教师使用大量的视觉教具。

3. Telescopes and microscopes are visual instruments.
    望远镜和显微镜是光学仪器。

1. 视觉的;视力的;可见的
    Visual means relating to sight, or to things that you can see.

    e.g. ...the graphic visual depiction of violence.
           对暴力赤裸裸的影像描绘
    e.g. ...music, film, dance, and the visual arts.
           音乐、电影、舞蹈和视觉艺术

2. 视觉材料（指用于展示或说明的图画、表格、影片等）
    A visual is something such as a picture, diagram, or piece of film that is used to show or explain something.

    e.g. Remember you want your visuals to reinforce your message, not detract from what you are saying.
           要记住，使用视觉材料是为了使表达的意思更加清楚明白，而不能分散对所讲内容的注意力。