4.6 vision is generally measured by the standard logarithmic scale, which corresponds to 0.4 on the fractional recording scale, and it is recommended to have your vision tested by a regular optometrist. Fractional charts are the old charts that we used to use, the new charts are standard logarithmic charts, and 4.6 corresponds to 0.4. The new charts are now used in clinical checkups and eye exams because they are more accurate. If a child has 0.4 vision, a dilated optometry is usually needed to determine whether myopia and astigmatism are present; if an adult suddenly develops 0.4 vision with vision loss, it may be due to a disease such as keratitis; and if an elderly person has 0.4 vision, it may be due to the development of cataracts. Any loss of vision requires prompt medical attention.