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Julie Calvert, Michael S. Bradnam, Velitchko Manahilov, Daphne L. McCulloch, Ruth Hamilton, Gordon N. Dutton; VEP measures of contrast sensitivity in infants and children from 2 months– 15 years of age. Journal of Vision 2006;6(6):288. doi: 10.1167/6.6.288.
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© ARVO (1962-2015); The Authors (2016-present)
Children with neurological impairment often have visual dysfunction, including reduced contrast sensitivity (CS). However, a lack of co-operation or developmental delay can make subjective testing slow and inaccurate. We have developed an automated, objective CS test using steady-state visual evoked potentials (ssVEPs) suitable for this difficult to test group. In the present study we show the normal development of CS using the ssVEP test as well as age-appropriate psychophysical tests.
The rationale for our technique is to acquire the most important information as quickly as possible, before the child loses co-operation. This is accomplished by real-time analysis of the individual's ssVEP which determines the subsequent contrast levels to be presented. The stimulus presentation technique is based on an adaptive staircase method. We assessed contrast thresholds in 72 infants and children using our VEP test as well as age-appropriate psychophysical tests (Hiding Heidi, Lea symbols, a PC based psychophysical staircase, F.A.C.T sinewave grating chart and the Pelli-Robson chart).
With the ssVEP technique, contrast thresholds, comparable to the psychophysical test results, were reached in less than three minutes. CS increased as a function of age until around 5 years, when it reached a plateau at adult levels.
The use of ssVEPs, combined with sensitive objective signal detection and a staircase stimulus presentation is a rapid and valid strategy for determining contrast sensitivity in infants and children. This direct method of assessing contrast sensitivity, when behavioural responses are not required, demonstrates increasing sensitivity to contrast throughout a child's first 5 years.
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