Eye exam charts do not change on a regular basis. There are, however, a variety of different charts that are widely used to measure visual acuity. Therefore, the eye exam chart may differ depending on where the exam is taking place and who is being examined.
Eye exam charts have been standardized because it is felt that a standard method of measurement is necessary in order to achieve uniform diagnosis. While variants have been developed over the years, such as charts designed for adults and children unable to read, or charts designed to be more scientific, the charts themselves have remained fairly static.