Development of superimposing electroretinogram for identifying the retinal layer causing a decline in visual sensitivity at arbitrary points on the retina

Abstract

AbstractPurposeAlthough the decline in visual sensitivity of the retina can be measured by microperimetry, it is difficult to identify the retinal layer causing this decline. We investigated cryptogenic diseases, such as macular dystrophy, by developing an electroretinogram (ERG) superimposing seven multifocal hexagonal stimulus arrays on the background of a multifocal array.MethodsThis apparatus is made of illumination and photographic optical systems separated by a mirror with a hole. In addition, it is made of a microperimetry optical system and an ERG optical system separated by a cold mirror. The device consists of an Edmund infrared camera EO‐50231, a lens with a 25‐mm focal length, a halogen lamp, an objective lens with a 50‐mm focal length, 4 double convex lenses with a 100‐mm focal length, 2 aperture stops, a mirror, a 45° cold mirror, an 8‐inch monitor and an artificial eye. We deployed a differential amplifier with gain 10, high‐pass filter with a 21.2‐Hz cut‐off frequency, 60‐Hz notch filter and two non‐inverting amplifiers with gains 1001 and 11. Moreover, we used the National Instruments' I/O device USB‐6212, the Nihon Kohden's plate electrode NE‐113A, the Nihon Kohden's electromagnetic shield sheet Y049 and the LabVIEW 2018 software for data retrieval. The background of the ERG software consists of 11 layers and 330 arrays and uses seven arrays as the examination target. The centre of these seven arrays has the same area, with an array directly placed under it on the background; and the system superimposes these arrays. We developed the ERG software, which was able to display the adjusted background from 18.0 to 30.0 mm and it almost did not have the delay time of a flicker stimulation as the frequency was changed from 10 to 100 Hz. The ERG software was shown on an HP Pavilion 32‐inch HDR display.ResultsAt the arbitrary position on the fundus, the superimposing ERG was able to measure all waveforms: a wave, b wave, c wave, and photopic negative response. Cone ERG and bright flash ERG were good.ConclusionsIt is expected that the superimposing ERG function would identify the retinal layer causing visual alterations at specific points throughout the retina. Further work towards pre‐clinical animal testing and clinical evaluation are required.