FUNCTIONAL IMAGING OF THE RETINA USING THE MULTIFOCAL ELECTRORETINOGRAPH - A CONTROL STUDY

Background - A new technique exists that enables functional mapping of the retina. A control population was examined to obtain normative val ues and to assess the reproducibility of this new test. Methods - Twen ty healthy volunteers were tested using a 61 hexagonal array stimulus with a 14 minute recording period. Median 5th and 95th percentiles wer e determined for implicit times and amplitude measures for the 61 test areas. Repeat measurements were performed on 10 individuals. Wilcoxon and Bland and Altman techniques were used to quantify reproducibility of the test. Results - The implicit time of the waveform components w as not found to vary over the retina (peak or b-wave component, 35.52 (1.4) ms; trough or a-wave component, 17.76 (0.8) ms). Reproducibility was found to decrease with eccentricity (coefficient of repeatability 17.4% for the central area increasing to 30.3% for the peripheral rin g). Conclusions - The findings suggest that reproducibility, although variable with eccentricity, is comparable with conventional electrophy siology. These limits of variation were used to assign confidence inte rvals to individual retinal areas and will be used (future work) in th e examination of diseased states.