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X. Wu, X. Zhang, Y. Sun, Y. Gong, P. Zhu, X. Xu; Fourier Analysis of Focal Flicker Responses in Age Related Macular Degeneration . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1821.
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Purpose:To understand the sites and physiological characteristics of the macular dysfunction in age related macular degeneration (ARMD) by means of Fourier analysis of focal flicker electroretinogram. Methods:The study included 68 nonexudative ARMD cases (120 eyes) and exudative 56 nonexudative ARMD cases (82 eyes), 60 age-matched normal subjects (120 eyes) as a control group. Macular focal electroretinogram in response to sinusoidal stimuli flickered at 10 and 30 Hz were recorded in all of the cases as well as the control group with contact lens electrode and a hand-held stimulator (Maculoscope) with direct visualization of the fundus through dilated pupils. The spot light stimuli were 3 and 5 degrees at macular region. The amplitudes and phases of the Fourier analyzed fundamental harmonic (1f) and second harmonic (2f) components were measured. Results:Compared to controls, patients with nonexudative and exudative type showed losses of both 1f and 2f amplitudes, the ratio of fundamental to harmonic component (1f/2f) showed normal or an slight alteration in the nonexudative type, but a significant alteration in exudative type. On average, 2f decreased more quickly than 1f and 1f/2f tended to increase with the course of disease. The results also showed a significant delay not only in nonexudative but also exudative type. There was a significant correlation between amplitudes of macular focal flicker electroretinogram and visual acuity in ARMD cases. Conclusions: This study suggests Fourier analysis of focal flicker electroretinogram could give much important information about the disturbance of the macular function in ARMD cases, and both receptoral and postreceptoral sites contribute to macular dysfunction. It would be of clinical value to obtain a fundamental-harmonic ratio in order to evaluate objectively the disturbance in the different site of macular, and also is helpful for the assessment of prognosis in ARMD cases.
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