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B. Link, A. Juenemann, F.K. Horn; Multifocal Pattern ERG With Stimulation by LED Arrays and Cyclic Summation –Results in Healthy Subjects, Ocular Hypertensives and Glaucoma Patients . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4008.
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© ARVO (1962-2015); The Authors (2016-present)
Pattern stimulation is widely used to detect inner–retinal dysfunction. PERG is a mass response, while multifocal techniques are able to show localised defects. Perimetry is a subjective way to test for glaucomatous damage. The idea of objective perimetry remains challenging. Thus we constructed a multifocal pattern stimulation set which allows the application of cyclic summation. In this work we describe a new pattern stimulation technique with LED areas and show results in healthy subjects, ocular hypertensives and glaucoma patients.
The pattern stimulator uses 13 LED arrays, each consisting of 10x10 white LEDs. The LED arrays (Roland Consult, Germany) stimulated with the cyclic summation technique (Doc Ophthalmol, in press) at a basic temporal frequency of 16 RPS. Spatial frequency was 0.58 cyc/deg, which was determined by the viewing distance (30 cm). Luminance was 340 cd/m² (bright field). Adequate correction glasses were provided. 18 healthy control subjects, 17 ocular hypertensives and 38 glaucoma patients were examined with the LED stimulator. Amplitude and phase of each array were compared with the local perimetric mean defect corresponding to each LED array.
The present technique allows PERG recordings with a good signal–to–noise ratio. Healthy subjects [MD: –0.8 ± 1.3 dB] have a high PERG amplitude centrally (1.4 ± 0.6 µV) and decreasing PERG amplitudes to the periphery.
Central PERG of ocular hypertensives [MD: –0.8 ± 1.0 dB] did not differ significantly from the healthy control group.
Glaucoma patient group [MD: 4.4 ± 5.6 dB] shows a significantly reduced PERG amplitude measured with the central (1.0 ± 0.4 µV, p < 0.01) and peripheral LED arrays. A correlation between local perimetric mean defects and the focal PERG amplitude could not be seen in the present patients.
Peripheral retinal responses can be elicited with a checkerboard pattern reversal LED–stimulator. Our results support the hypothesis of a generalised ganglion cell defect in glaucoma disease rather than localised damage.
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