Abstract

P 197

Multifocal-ERG in macular diseases – fundus controlled examination in comparison to conventional monitor stimulation

Springer C., Weimer P., Rohrschneider K.
Department of Ophthalmology, University of Heidelberg

Objective: Multifocal electroretinogram (mfERG) enables an objective assessment of central retinal function. However, an instable fixation can cause artifacts. With the RETIscan-VISUCAM-system a fundus controlled mfERG is possible and such artifacts can be avoided. Eye movements are monitored during the examination with an infrared camera and a superposition of mfERG-results with a colour fundus picture is possible. Aim of this study was to compare results of fundus controlled examinations with those of conventional monitor stimulation.
Methods: 16 eyes of 16 patients (8 men, 8 women, mean age 43 years) with different macular diseases were recruited consecutively and a mfERG was carried out with the RETIscan-System (Fa. Roland Consult) with conventional monitor stimulation (CRT monitor) as well as with the VISUCAM-(Zeiss Inc.) system under direct fundus control. MfERG results were compared between both systems regarding topography and P1 amplitudes.
Results: In all patients comparable results between both methods were found. Fixation was sufficiently stable in all patients to derivate a foveal signal. For fundus controlled mfERG a 19 hexagon pattern proved to be reasonable and at least 4 cycles had to be completed to obtain comparable results to those of monitor stimulation. Artifacts caused by fixation instability could be detected easily and in this case examination cycles were repeated for averaging. Pathologies were presented in a comparable manner with both instruments.
Conclusions: Fundus controlled mfERG represents a reasonable advancement of conventional mfERG, since eye movements can be monitored directly. An accurate correlation of mfERG signals to retinal pathology can augment mfERG quality especially in eyes with instable fixation. Further studies are needed to evaluate if fundus controlled mfERG improves mfERG reliability and accuracy.

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