Abstract
Purpose :
Microperimetry is used to measure the decline in visual sensitivity of the retina, and the superimposing multifocal ERG, which measured a-wave, b-wave, c-wave, and photopic negative response (PhNR), is used to identify the retinal layer causing this decline. This study aimed to investigate the use of focal macular electroretinogram (ERG) function in fundus-related perimetry (microperimetry) for evaluating cryptogenic diseases such as macular dystrophy. A focal macular ERG function was used for microperimetry instead of the superimposing multifocal ERG.
Methods :
The apparatus including illumination and photographic optical systems separated by a mirror with a hole, a microperimetry optical system, and an ERG optical system separated by a 45° cold mirror was developed. The electrical measuring equipment consisted of a differential amplifier, a high-pass filter, a 50-Hz notch filter, two non-inverting amplifiers, the function input/output device, plate electrodes, and the LabVIEW software. A 49-inch ultrahigh brightness (3,500 cd/m2) liquid crystal display (LCD) was prepared for focal macular ERG. The focal macular ERG software demonstrated three sizes of stimulus spot circles, including 5°, 10°, and 15° in diameter, on the ultrahigh brightness LCD. Notably, the stimulus spot circle could be shown because the circle’s center was adjusted to an examination target’s center of the microperimetry. We used the spot circle of 5°, 10°, and 15° in diameter at the center changing frequencies of 10, 20, 30, 40, and 50 Hz, respectively. Moreover, we used the spot circle of 10° diameter on a circumference of 20° diameter, right to left or up and down, and the spot circle of 15° diameter on a circumference of 40° diameter. Five healthy people in their 20s-50s were measured.
Results :
The focal macular ERG measured the a-wave, b-wave, and PhNR. Further, certain small waves on the b-wave were confirmed with high probability as being oscillatory potentials (OPs), while one positive wave similar to the d-wave was sometimes confirmed after the b-wave, but the c-wave was not confirmed.
Conclusions :
The focal macular ERG function identified the retinal layer causing visual alterations at specific points throughout the retina when not only the a-wave, b-wave, and PhNR but also the OPs and d-wave are confirmed. Moreover, the superimposing multifocal ERG will be required because it measures the c-wave.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.