Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: ANSI Z80.21:2010
• Năm ban hành / Publication date: 2010
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: Ophthalmics - Instruments - General-Purpose Clinical Visual Acuity Charts
• Thay thế cho / Replace: ANSI Z80.21:1992
• Số trang / Page: 18

Phạm vi áp dụng / Scope of standard

This standard applies to displays of optotypes for all clinical
visual acuity measurement systems that use recognition of
high-contrast optotypes and that are designed for general use
including optotypes printed on opaque media, those intended for
transillumination, electronically generated or projected displays.
It does not apply to special testing of visual acuity, e.g.,
low-vision or low-contrast charts.

Purpose

The principles of standardized visual acuity testing are
presented in standards adopted by the National Academy of Sciences
and the Consilium Ophthalmologicum Universal as referenced below.
Due to practical design considerations and physical limitations of
most general-purpose clinical visual acuity measurement systems,
the chart design features specified in these reference standards
can only be met for a limited range of acuity presentations.
Specialized charts are often required for special clinic visual
acuity measurements - such as for low-vision patients. The purpose
of this standard is to provide for standardized visual acuity
charts for general measurement, which will enable the measurement
of visual acuity over a limited, but clinically useful, range of
acuities according to the principles contained in the reference
standards.