Cone electroretinogram to chromatic stimuli in myopic eyes

The cone electroretinograms (ERGs) to different chromatic stimuli were recorded in myopic subjects. Ganzfeld color flashes under bright white background illumination were used to elicit short-wavelength-sensitive (S-), and mixed long-(L-) and middle-(M-) wavelength-sensitive cone ERGs. Nineteen subjects with mild myopia (between -3.0 and -6.0 D), 12 subjects with high myopia (greater than -6.25 D) but without chorioretinal atrophy or posterior staphyloma, and 22 age-matched normal controls were compared. The S-cone and L,M-cone b-wave amplitudes decreased progressively with increasing myopia. The amplitudes of the S-cone and the L,M-cone b-wave were significantly lower in highly myopic subjects, as compared with controls. The implicit times of both b-waves were normal in most myopic subjects. The S-cone and the L,M-cone ERGs were almost equally affected in myopic eyes. The selective reduction of the S-cone pathway in high myopia, reported previously, may not originate from the other retina.