Three dimensional analysis (XY plane and time) of averaged electroretinograms for the evaluation of rhegmatogenous retinal detachment and related pathological conditions

: Retinal functional imaging in patients with rhegmatogenous retinal detachment and related pathological conditions was investigated by three dimensional analysis of ERG topography. The three dimensional analysis revealed that the area of maximal amplitude deviated to the skin area closest to the location of the retinal detachment (paradoxical localization). In temporal retinal detachment, for example, the maximal amplitude of the a- and b-waves deviated toward the temporal side on the surface topography. The depth of the retinal detachment was clearly indicated by differential ERG topography. Flicker ERG with a stimulus frequency of 30Hz was especially successful in showing the existence and location of macular detachment within the area surrounding the temporal vascular arcades. ERG topography also indicated the meridional extent of retinal detachment. When there was detachment in two quadrants (e.g., two inferior quadrants), deviation in the surface topography of a- and b-waves appeared in the same quadrants. When detachment expanded into three quadrants, deviation of the amplitude of a- and b-waves closely resembled the extent of the detachment. In addition, however, there was inverse a- and b-wave surface topography on the opposite skin area. When there were two quadrants of retinal detachment, there were two quadrants of inverse a-and b-waves. When there were three quadrants of retinal detachment, there was only one quadrant of inverse a- and b-waves. No inverse a- and b-waves were detected when there was only one quadrant of retinal detachment. In such cases, however, deviation in the surface topography covered three quadrants. These abnormalities were detected in 90.6% of all cases with the retinal detachment disappeared after the retina was reattached. While the buckling procedure and argon laser retinopexy had little effect on the topographical distribution, it was markedly distorted by cryoretinopexy. No remarkable changes in the topographical distribution of a- and b-waves were detected in pathological conditions related to rhegmatogenous retinal detachment. This new method for functional imaging of the retina should be valuable for objective clinical evaluation of retinal detachment.