DEVELOPMENT OF THE VEP TO LUMINANCE MODULATION

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The project proposed here concerns the validation of a new test procedure to assess infant visual function and to detect amblyopia in the first year of life. The test uses as an input a pseudorandom sequence of luminance modulation and as an output the visually evoked potential. The test is simple to conduct, requires only 43 secs of data collection to test an eye, is not affected by refractive errors or accommodation, and requires minimal cooperation from the infant subject. The stimulus mimics band-pass limited white noise but contains a periodicity which allows signal averaging. In a preliminary study reported here, a method is described to extract the maximum input frequency driving the response (MDF). Using 14o nearly homogeneous fields a developmental sequence was estimated in 19 infants in which MDF ranged from a 4 Hz at 4 weeks to 13 Hz at 44 weeks postnatal age. The adult maximum driving frequency was 19 Hz. Surprisingly, 6 adult amblyopes all had unequivocally abnormal test results in their amblyopic eyes suggesting a developmental arrest at 3 months of age. The proposal concerns both the implementation of the test in a larger normal infant population and the exploration of the reason for the results in adult amblyopes.