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Evaluation of methods for assessing visual function of infants
T C Prager1, Y L Zou, C L Jensen
1Department of Ophthalmology and Visual Science, University of Texas Health Science Center, Houston, USA. tprager@ibm.net
Insights
Comparing infant vision tests, transient VEP latency showed the lowest variability. While all methods detect visual maturation, they assess different aspects of vision and are less reliable for individual infant assessment.
Area of Science:
- Ophthalmology and Visual Science
- Developmental Neuroscience
Background:
- Infant visual acuity and function estimation methods vary.
- Existing methods may not accurately predict long-term visual outcomes.
- Test-retest variability and comparative analyses are often lacking.
Purpose of the Study:
- Evaluate test-retest variability of infant vision assessment methods.
- Compare different visual acuity and function estimation techniques.
- Assess the predictive validity of these methods for infant visual development.
Main Methods:
- Assessed test-retest variability of Teller Acuity Cards (TAC), sweep visual evoked potential (VEP), and transient pattern VEP (latency and amplitude).
- Compared visual function estimates from these methods in 118 infants.
- Correlated method estimates and evaluated detection of maturational changes (4-8 months).
Main Results:
- Transient VEP latency demonstrated the lowest test-retest variability (3% difference, 7% SD).
- Sweep VEP, TAC, and transient VEP amplitude showed higher variability.
- Correlations between methods were poor, indicating they measure different visual aspects.
- All methods detected expected visual maturation between 4 and 8 months.
Conclusions:
- All evaluated methods offer reliable group data for infant vision.
- Individual infant visual assessment is less reliable with these methods.
- Each testing method captures distinct visual function components.
- All methods effectively identify visual maturation in infants aged 4-8 months.
Purpose:
Commonly used behavioral and electrical testing methods for estimation of visual acuity and visual function in infants yield different estimates and may not accurately predict visual acuity and visual function in later life. Moreover, neither test-retest variability nor side-by-side comparisons of the various methods have been thoroughly evaluated in the same infant population. The purpose of this study was to provide such an evaluation.
Method:
The test-retest variability of visual acuity and visual function was evaluated for the Teller Acuity Card (TAC) procedure, sweep visual evoked potential (VEP), as well as latency and amplitude measured by transient pattern VEP. Groups of approximately 20 infants contributed test-retest data. Visual function estimated by the various methods in a larger group of infants (n = 118) was compared. Correlations between methods and the validity of the various methods to detect maturational changes between 4 and 8 months of age were also assessed. Administration of these tests was according to standard and usual procedures.
Results:
The average percent difference between test and retest estimates of acuity as well as the SD was lowest for transient VEP latency (3%, 7% SD). The other methods were markedly more variable: sweep VEP (2%, 22% SD), TAC procedure (8%, 20% SD), and transient VEP amplitude (7.5%, 39% SD). Average coefficients of variation showed a similar trend: transient VEP latency, 8%; sweep VEP, 15%; TACs, 30%; and transient amplitude, 53%. Correlations among estimates by the methods were poor, but expected changes in visual maturation from 4 to 8 months of age were detected with all methods.
Conclusions:
All methods evaluated provide valid and reliable test-retest data for a group, but are less valid for estimating visual acuity and visual function of an individual subject. The poor correlations between any 2 of the testing methods suggest that each test assesses a different aspect of vision. Nonetheless, expected maturational changes between 4 and 8 months of age were readily detectable by all methods evaluated.