Description
The EDTRS ILLITERATE E chart is an essential tool for accurately measuring visual acuity in individuals who may not recognize standard letters. This specialized chart employs the letter "E" in four distinct orientations—up, down, left, and right—allowing subjects to indicate the direction of the "E"'s legs. This design makes it particularly suitable for those who are illiterate or have language barriers.
Key Features
- Testing Distance: Optimized for use at a 4-meter distance, though adaptable to varying distances as needed.
- LogMAR Measurement: Visual acuity results are expressed in logMAR units, providing a precise and standardized assessment.
- Chart Composition: Comprises 14 lines, each containing 5 optotypes, with a visual acuity range from 1.0 logMAR to -0.3 logMAR.
- Incremental Precision: Each correct response adjusts the score by a 0.02 logMAR increment.
- Luminance: Maintains a chart luminance of 200 cd/m² for consistent visibility.
Intended Use
This chart is designed for comprehensive visual acuity assessment, both in unaided and best-corrected conditions. It is particularly useful in clinical and research settings for:
- Monocular Testing: Each eye is tested separately, aligning with the Berkeley Rudimentary Vision Test (BRVT) protocol.
- Classification Boundaries: Helps confirm visual impairment classification boundaries, crucial for determining the 'good visual acuity' border within the B3 and B4 ranges.
Common Applications
The EDTRS ILLITERATE E chart is widely used in:
- Clinical Environments: Providing reliable visual acuity assessments at each patient visit.
- Research Settings: Offering a standardized method to evaluate visual acuity across diverse populations.
By facilitating accurate and accessible visual acuity testing, this chart plays a vital role in eye care diagnostics, ensuring that practitioners can effectively assess and address the visual needs of their patients.
