KCNV2 and X-linked retinoschisis: Furthermore, as more is understood about retinal diseases, ERG responses with specific changes in the waveform allow it to act as a non-invasive diagnostic tool, such as for KCNV2 retinopathy and Juvenile X-linked retinoschisis (Sieving et al., 1999; Kutsuma et al., 2019).