Objective To observe the changes on multifocal electroretinography (MfERG) in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment (RRD).Methods MfERG was performed in 66 patients (66 eyes) which were grouped into: emmetropes (n=22) as the control eye; high myopes without fundus lesions (corrected visual acuity ≥1.0, n=15); and fellow eyes of high myopics with RRD (n=29). The first-order kernels N1, P1, N2 response density and latency were analyzed.Results When compared with the emmetropes group, the high myopes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 (P<0.05), delayed N1 wave latency in rings 3 to 6, and P1 wave latency in rings 3 to 5 (P<0.05). The fellow eyes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 and significantly delayed N1 and P1 wave latencies in rings 3 to 6 (P<0.05) compared with the emmetropes group. Compared with the high myopes group, P1 wave response densities in rings 1 to 6, N1 wave response densities in rings 1, 3, 4, and 6, and N2 wave response density in ring 1 were significantly decreased in the fellow eyes group (P<0.05); whereas there were no significant differences in latencies between the two groups (P>0.05). Conclusion MfERG can sensitively assess the early changes in visual function in fellow eyes in patients with RRD. Objective To observe the changes on multifocal electroretinography (MfERG) in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment (RRD). Methods MfERG was performed in 66 patients (66 eyes) which were grouped into: emmetropes (n = 22) as the control eye; high myopes without fundus lesions (corrected visual acuity ≥1.0, n = 15); and fellow eyes of high myopics with RRD (n = 29) Results were compared with the emmetropes group, the high myopes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 (P <0.05), delayed N1 wave latency in rings 3 to 6 , and P1 wave latency in rings 3 to 5 (P <0.05). The fellow eyes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 and significantly delayed N1 and P1 wave latencies in rings 3 to 6 (P <0.05) compared with the emmetropes group. Compared with the high myope N1 wave response densities in rings 1, 3, 4, and 6, and N2 wave response densities in rings 1 to 6 were significantly decreased in the fellow eyes group (P <0.05); there was no significant differences in latencies between the two groups (P> 0.05). Conclusion MfERG can sensitively assess the early changes in visual function in fellow eyes in patients with RRD.