Description

Teller Acuity Cards, crafted by Precision Vision, Inc. under license from the University of Washington, are specialized tools designed to assess visual acuity in infants, young children, and individuals with special needs. These cards are particularly beneficial for those unable to perform standard letter or symbol acuity tests.

Key Features

• Preferential Looking Technique: The cards employ a unique method where high-contrast black-and-white gratings are used to gauge the subject's gaze or behavioral response. This technique helps determine the finest grating the individual can detect, providing an accurate estimate of their visual acuity.

• Card Specifications: Each card measures 25.5 x 55.5 cm and includes a central peephole for examiner observation. The design features vertical square-wave gratings on one half of the card, with varying spatial frequencies to cover a broad range of visual acuities.

• Set Variations: Available in full sets (16 or 17 cards) and half sets (8 cards), these cards offer a comprehensive range of spatial frequencies from 0.23 to 26.0 cycles/cm, corresponding to acuity levels approximately from 20/30 to 20/3200.

Testing Parameters

• Distance and Conditions: Testing is conducted at specific distances suitable for different age groups, with conditions such as minimum luminance carefully controlled. The test duration typically ranges from 6 to 13 minutes, depending on the subject's age and cooperation.

• Clinical Validation: The cards are backed by extensive normative and clinical studies, demonstrating reliability, precision, and consistency in pediatric populations. They provide valuable normative data for both binocular and monocular visual acuity.

Advantages and Limitations

• Advantages: Teller Acuity Cards offer a simple and reliable method for assessing visual function in non-verbal and preverbal patients. They are effective in the early detection of significant visual disorders, making them a vital tool in ophthalmology, optometry, and developmental practice.

• Limitations: The cards may be less suitable for detecting low-grade amblyopias or assessing distance acuity. Additionally, they may be relatively time-consuming with uncooperative patients and come at a higher expense compared to some alternatives.

Maintenance and Care

To ensure longevity, the cards should be stored flat, away from moisture and direct sunlight. Cleaning should be done gently with a soft, dry cloth. Each set includes an instruction manual with normative data and conversion tables, aiding practitioners in effectively utilizing the cards for accurate visual assessment.