The Sonksen logMAR Test of Visual Acuity: I. Testability and reliability

Area of Science:

• Ophthalmology
• Pediatric Optometry
• Vision Science

Background:

• Accurate visual acuity measurement is crucial for early detection of vision impairments in children.
• Existing tests may not be suitable for very young children, limiting early diagnosis and intervention.
• A standardized, reliable test is needed to assess visual acuity across a wide pediatric age range.

Purpose of the Study:

• To develop a standardized logMAR (Logarithm of the Minimum Angle of Resolution) test for visual acuity in young children.
• To establish the testability and reliability of this new visual acuity test in a pediatric population.

Main Methods:

• A population sample of 4671 children aged 2 to 8 years 6 months was recruited from schools and preschools.
• 2991 children were tested using a standardized logMAR visual acuity test, recording their ability to name/match letters, accept occlusion, and achieve binocular/monocular linear visual acuity measures.
• Inter- and intra-tester reliability was assessed on a subset of 215 children.

Main Results:

• The test demonstrated high success rates: 99.4% could name/match letters, 99% achieved binocular single vision, 98% achieved binocular linear acuity, and 94% achieved monocular linear acuity.
• Testability increased with age, with 50% of children under 3 years achieving binocular linear measures, rising to 99% for those 4 years and older.
• Reliability was high, with 95% limits of agreement of +/-0.13 and -0.19/+0.15 for binocular and +/-0.16/+0.15 and -0.17/+0.13 for monocular measures.

Conclusions:

• The Sonksen logMAR Test is a reliable tool for measuring binocular and monocular linear visual acuity.
• The test is highly testable in a significant proportion of children starting from 2.5 years of age.
• This standardized test facilitates early and accurate visual acuity assessment in young children.