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L. Ziccardi, G. Stifano, L. Montrone, G. Iarossi, E. Merendino, A. Scupola, B. Falsini, A.M. Minnella; Macular Electroretinograms to Cone Specific Stimuli in Age–Related Maculopathy . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2103.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify macular Long (L)– and Middle (M)–wavelength cone–driven responses in age–related maculopathy (ARM)
Macular Electroretinograms (ERGs) in response to uniform field (18°) red (R)–green (G) flickering (41 Hz) stimuli, modulated in counterphase with a luminance color ratio (R/R+G) corresponding to the points of L–cone and M–cone silent substitution (L–cone: 0.78; M–cone: 0.46) were recorded in 18 ARM patients (age range: 58–81 yrs) with relatively preserved visual acuity (> 20/40) and normal color vision (Farnsworth D–15, Ishihara plates), as well as in 15 age–matched control subjects. The ERG fundamental response component amplitude and phase, isolated by Fourier analysis, were measured
When compared to controls, patients showed a loss in both L– and M–cone driven ERGs amplitude (by 48 and 25%, respectively, p < 0.05). ERG M–cone, but not L–cone–driven responses had a substantial phase delay (by 100°, about 6.5 milliseconds, p < 0.01). The mean L–cone response losses of patients were greater (p < 0.05) than corresponding M–cone losses. L–cone driven response losses of individual patients were significantly correlated with visual acuity (p < 0.05)
Although the responses driven by both macular M– and L–cones are on average reduced in ARM, the present findings show that at least in some patients selective L–cone–driven losses may occur. M–cone phase delays are likely to reflect abnormalities in post–receptoral processing
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