[Evaluation of typical and atypical retinal pigmentary dystrophy by three dimensional analysis (XY plane and time) of averaged electroretinograms].

Retinal functional imaging of patients with typical and atypical retinal pigmentary dystrophies was investigated by three dimensional (XY plane and time) analysis of ERG topography by comparing visual field and fluorescein angiographic findings. The three dimensional analysis revealed that the area of maximal amplitude deviated to the skin area closest to the dominant location of the retinal pigmentary dystrophy (the so-called paradoxical localization). In patients with temporoinferior sectorial retinal pigmentary dystrophy, for example, the maximal amplitude of the a-, b-waves and retinal oscillatory potentials deviated toward the temporoinferior side on the surface topography. These characteristic phenomena of a- and b-waves were found in 60.8% of all patients. Flicker topography with a stimulus frequency of 30 Hz was especially successful in showing the existence and location of paramacular involvement of retinal dystrophy within the area surrounding temporal vascular arcades. The detectability of macular asymmetric involvement was 65.2%. No significant topographic changes were detected in cases in the early stage with no remarkable visual field defects, or in the end stage with remarkable concentric field defects and complicated glaucomatous visual field defects. A comparative study of topographic changes, visual field changes and fluorescein angiographic findings showed that topographic changes in the a-, b-waves, retinal oscillatory potentials and 30Hz flicker components coincided more closely with visual field changes than fluorescein angiographic findings. We proposed that retinal pigmentary dystrophy is not a homogeneous lesion in its progression and believe that the ERG topography method can, by the imaging of dominant locations, detect this disease as well as visual field testing.

[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.