Abstract
Abstract: :
Purpose:The inference of psychophysical and cortical evoked potential data is that central retinal function is immature in young infants. We have used the multi-focal ERG (mfERG) to test this hypothesis directly, and to characterize the retinal immaturity. Methods: mfERG responses to scaled and unscaled arrays of 61 hexagons were recorded from 10- week- old infants (N=9) and adults (N=8) using the VERIS system. Fixation was monitored. The amplitude and implicit time of the averaged responses in each of five concentric rings were determined for every subject. Results:In every ring, the median response amplitudes were lower in infants than in adults, and in both infants and adults, amplitude decreased with eccentricity (Center Ring 1: 29 vs 61 nV/deg2, Ring 2: 16 vs 38 nV/deg2, Ring 3: 13 vs 30 nV/deg2, Ring 4: 12 vs 23 nV/deg2, Ring 5: 14 vs 20 nV/deg2). Amplitude varied significantly with age (F= 45.6, p < 0.01) and eccentricity (F= 15.5, p <0.01). Implicit times, on the other hand, did not vary with eccentricity although the implicit times of infants (Median 32 ms) were longer than those of any adult (Median 27 ms). Adults’ results for the scaled and unscaled conditions were similar, but the infants’ unscaled amplitudes did not show variation with eccentricity. Conclusion:These mfERG data demonstrate cone mediated processes in the central retina are conspicuously immature at age 10 weeks when peripheral cone mediated responses to full field ERG stimuli are relatively mature (Hansen & Fulton, ARVO 1997).
Keywords: 623 visual development: infancy and childhood • 396 electroretinography: non-clinical • 564 retinal development