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Multifocal pattern ERG in glaucoma and NNO
S. Stiefelmeyer, G. Rudolph, T. A. Berninger
Introduction: Patients with acute optic neuritis and chronic glaucoma were examined with multifocal PERG.
Methods: We examined 52 normal volunteers (27 RE, 25 LE, aged 21-72, median 41,5), 34 volunteers with glaucoma (primary and secondary open-angle and low tension glaucoma, 16 RE and 18 LE, aged 41-78, median 67,4) and 6 patients with retrobulbar neuritis (2 RE and 4 LE, aged 23-47, median 21,5) with the multifocal pattern ERG technique (RETISCAN System, software version 3.11.1, Roland Consult, Germany).The eyes were anesthesized and the refractive errors were corrected. We used a stimulus pattern of 16 hexagons, each consisting of 6 triangles (alternating black and white areas). The pattern changes in accordance to the structure of a corrected m sequence (length 512, 8 cycles with 39 second each). For all recordings loop electrodes were used ( references electrodes at the temple and the ground electrodes at the forehead). Screen distance was 30cm and a visual field of 60° was stimulated. The signals were bandpass filtered with 100 Hz. Only patients with refractive errors less than 6 dpt were included in the study.
Results: The multifocal PERG was analysed in regard to amplitude and latency of the positive and following negative response. A significant difference for the positive and negative response was observed. The positive component was significantly reduced for the central and the second ring (p<0,05), while there was no significant difference observed for the third ring. By contrast for the negative component the central ring remained unchanged in comparison to normals while there was a significant decrease of amplitude for the second and third ring (p<0,05). Similar observations were made for the acute NNO.
Discussion: The different behaviour of the positive and negative compo-nent in glaucoma of the optic nerve prove once more that both components are generated in different retinal layers. The multifocal pattern- ERG seems to be a good method to follow-up patients with glaucoma.
The study was supported by Chibret, Germany
Department of Ophthalmology of Ludwig Maximilian, Munich, Mathildenstr. 8, D-80336 Munich