This Standard specifies design standards, printing dimensions, application method and visual acuity statistic method for visual acuity chart.
This Standard is applicable to distant and near optometry used for common physical examination, recruitment and employment of children at 3 or above, adolescent and adults; it may apply visual acuity disorder screening, ophthalmology and visual optics clinic by reference.
2 Terms and Definitions
For the purposes of this Standard, the following terms and definitions apply.
2.1
Optotype
Letter, digit and figure for visual acuity measurement
2.2
Visual angle
The angle of two points of an external object projecting on eye nodal point (N), expressed by (a) in (') (see Figure 1)
