Overview
EN ISO 8596:2018/A1:2020 is the CEN-adopted amendment to ISO 8596 (2017) governing ophthalmic optics - visual acuity testing. It defines the presentation of standard and clinical optotypes (visual acuity characters) and refines scoring for clinical testing. Amendment 1 (ISO 8596:2017/Amd1:2019) was approved by CEN and published as EN ISO 8596:2018/A1:2020 (January 2020) and updates the test scoring procedure in Annex A.5.
Key topics and technical requirements
- Standard and clinical optotypes: Specifies the use and presentation of optotypes used in visual acuity charts (standardized characters, symbols or tumbling shapes for testing vision).
- Presentation requirements: Covers how optotypes should be presented to patients - order, spacing and sequence - to ensure reproducible visual acuity measurements (as defined in the main ISO 8596 document).
- LogMAR scoring: The amendment updates the scoring approach using the LogMAR visual acuity scale. Specifically, Annex A.5 replaces the previous paragraph with a rule that the sum of the values of all correctly called optotypes is subtracted from the LogMAR value of the top line of the chart; the resulting LogMAR value plus 0.1 corresponds to the assigned visual acuity for the test. This clarifies how individual correct responses influence the final LogMAR acuity value.
- Conformity and national adoption: As a CEN-endorsed amendment, it is intended for national standardization across CEN member bodies.
Applications and users
This amendment and the underlying ISO 8596 standard are essential for:
- Optometrists and ophthalmologists conducting routine and specialized visual acuity assessments.
- Clinical practices and hospitals standardizing vision testing protocols for diagnosis, monitoring and record-keeping.
- Manufacturers of visual acuity charts and diagnostic equipment, ensuring charts and software implement the correct optotype presentation and LogMAR scoring.
- Clinical researchers and trial sponsors who require consistent, reproducible visual acuity endpoints across sites.
- Regulatory and standards professionals implementing or auditing ophthalmic testing procedures.
Related standards
- ISO 8596:2017 - Visual acuity testing: base standard describing standard and clinical optotypes and presentation.
- EN ISO 8596:2018 - European adoption of ISO 8596:2017, amended by A1 (this document).
Keywords: EN ISO 8596:2018/A1:2020, ISO 8596, visual acuity testing, optotypes, LogMAR, ophthalmic optics, clinical optotypes, vision testing, optometry, ophthalmology.
