| The study aims to investigate the retinal function in both myopic children and myopic adults, and the regional changes of retinal activity towards defocus signals, using the global flash multifocal electroretinogram (mfERG). This paradigm of mfERG stimulus generates the direct (DC) and induced components (IC), which illustrate the outer and inner retinal activities respectively. The results showed that the paracentral DC amplitude at low and middle contrasts, together with paracentral IC amplitude at all contrasts measured, were reduced in myopic adults. However, the effect of myopia on retinal function in myopic children was different from that in myopic adults. The mfERG response was not affected in myopic children, except the central DC amplitude at high contrast. Both the central DC and IC amplitudes at middle contrast, with some involvement of paracentral region, were reduced in children with progressing myopia. In addition, the paracentral retina reacted more vigorous to optical defocus than central retina. The paracentral DC amplitude was reduced under negative defocus and was not significantly changed under positive defocus. In contrast, the paracentral IC amplitude was increased under positive defocus and was not changed under negative defocus. This study clearly showed that the effect of myopia on retinal physiology between children and adults was totally different. The retinal function was generally unaffected in myopic children, except for the outer retinal function in the central region. As myopia progressed, the inner retinal function at central region, with some involvement of paracentral region, was reduced. There was a regional change in functional loss from central to paracentral region from children to adults with myopia. The inner retinal function at paracentral region was reduced in myopic adults, and the function at central region was generally unaffected. In addition, the retina could identify optical defocus and the paracentral retina reacted more vigorous to optical defocus. Therefore, the reduced retinal function at paracentral region in myopic adults is probably related to the effect of peripheral defocus on the myopic eye growth. This study enriches our understanding of the mechanism of myopia progression and assists in developing new myopia control treatment. |
