Objective To evaluate the variability of four parameters of multi-focal electroretinogram (mERG) a-wave amplitude, b-wave amplitude, awave latent period, b-wave latent period. Methods Sixty normal eyes of 46 volunteers were divided into 3 groups of different ages. RETIscan 3-12 system was used to carry out mERG examination. The stimulus matrix of 61 hexagonal elements spanning the central 24deg;of the visual field. These hexons were scaled with eccentricity and divide d into 5 rings. First-order kernel was selected. Results The variability of four parameters of mERG was great. The variability of b-wave latent period was the smallest, its coefficient of variatian was 4.52%～15.62%；that of a-wave latent period held the second place:10.29%~48.67%；that of b-wave amplitude was greater:25.92%~76.11%；that of a-wave amplitude was the greatest:43.82%~88.23%. The results of three groups showed that b-wave amplitude of ring 1 had the smallest variability. Conclusions The variability of latent period is smaller than that of amplitude; the variability of b-wave was smaller than that of a-wave. The longer the centrifugal distance, the lower the amplitude density of a-wave and b-wave. Physiological and anatomical factors might be important for the variability of parameters of multi-focal electroretinogram. (Chin J Ocul Fundus Dis, 2001,17:277-279)
Objective To measure and compare the difference between the normal control and retinoschisis with multifocal electroretinography. Methods Nineteen cases (21 eyes) of normal control and 8 cases (15 eyes) of inherited retinoschisis were measured with VERIS ScienceTM 4.0.Three cases (6 eyes) of inherited retinoschisis were tested with Ganzfeld ERG. Results There was statistically significant difference of average response density and latencies in all 6 ring retinal regions between the normal control and retinoschisis. The topography of multifocal ERG showed that multifocal amplitude decreased with disappearing or decreasing of central peak amplitude in patients with retinoschisis. The P1/N1ratio of the multifocal ERG average response densities in 6 ring retinal regions was different from the b/a ratio of the Ganzfeld ERG. Conclusion Each of the multifoca l ERG and Ganzfeld ERG has its advantage in the diagnosis of the retinoschisis. (Chin J Ocul Fundus Dis, 2001,17:268-270)