Abstract
Abstract: :
Purpose: Abnormalities in the b-wave of the flash ERG have been reported in 10-40% of patients with ONH. We have recorded pattern ERGs in ONH as a more specific indicator of inner retinal function. Methods: Photopic flash and pattern-reversal ERGs were recorded from 48 infants and young children (3.5-35 mo.) with unilateral or bilateral ONH. Pattern stimuli were presented during chloral hydrate sedation using an optical system including correction of the cycloplegic refraction. The disk diameter/disk macula ratio (DD/DM) measured from fundus photographs was used to classify ONH as moderate (0.15<DD/DM<0.3) or severe (DD/DM<0.15). Results: Pattern ERGs to large checks (4 deg.) were recordable 50/73 eyes with ONH and in all 13 fellow eyes tested (DD/DM≷0.3). Photopic flash ERGs were recordable in all eyes. Amplitudes of the photopic flash b-wave and the N95 component of the pattern ERG were each correlated with the severity of ONH as measured by the DD/DM (r2=0.1, p<0.01). Other indicators of ONH including double ring sign, tortuous vessels and disk pallor were also associated with smaller b-wave and smaller N95 amplitudes (p3.5mV) was recorded in 36% of eyes with moderate ONH and 29% of eyes with severe ONH. Conclusion: This study supports the hypothesis that dysgenesis of the inner retina is associated with ONH but the severity of this retinal involvement is variable. Approximately one third of our cases had severely diminished, unrecordable pattern ERGs while in other cases both the P50 and N95 components are well preserved.
Keywords: 487 neuro-ophthalmology: optic nerve • 395 electroretinography: clinical • 623 visual development: infancy and childhood