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G. Wu, J. Ha, M. L. Severns, J. Pollett, B. Shanker, R. Sreeraman, H. Uong, P. Nguyen; Ganzfeld 30 Hz Flicker ERG is Affected in Early AMD. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2171.
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To determine if there are changes in the 30 Hz flicker Ganzfeld ERG in eyes of patients with early Age-related Macular Degeneration (AMD). To our knowledge, there has been no previous study of the 30 Hz flicker ERG in this population.
Measurements were made on 21 eyes of 11 patients; 8 eyes had mild AMD (Snellen visual acuity of 20/20 to 20/40 with drusen visible on fundus photographs), and 13 eyes did not have AMD. None of the patients had other macular or retinal disease, or had previous laser treatment of the retina. Photopic 30 Hz flicker ERGs were recorded according to the ISCEV standard protocol using an EPIC-4000 system (LKC Technologies). Eyes were dilated and a DTL electrode was used for recording. Implicit time and amplitude of the ERG were measured by placing cursors on the waveform.
The age range of patients with AMD was 78 - 85 yrs (mean ± SD = 81.20 yrs ± 2.86); for non-AMD patients the age range was 64 - 80 yrs (72.43 yrs ± 6.58). The implicit time of the 30 Hz flicker ERG was significantly delayed in the patients with AMD (33.7 ms ± 7.4) compared to the non-AMD patients (29.0 ms ± 1.9, p = 0.036, t-test). The 30 Hz flicker amplitude was not significantly different between patients with AMD (82.4 µV ± 16.8) and non-AMD patients (87.9 µV ± 25.1, p = 0.59, t-test). Statistical significance of the results was unchanged after correction for age, using published norms.
Early AMD appears to cause a delay in the implicit time of the Ganzfeld 30 Hz flicker ERG, possibly indicating a generalized cone dysfunction.
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