The effect of age on short-wavelength sensitive cone electroretinograms and long- and middle-wavelength sensitive cone electroretinograms

We studied the effect of age on short-wavelength sensitive cone electroretinogram (S-cone ERG) and long-and middle-wavelength sensitive cone ERG (LM-cone ERG) using a contact lens electrode with a built-in light- emitting diode. We recorded ERGs in 31 pseudophakic subjects to avoid the effect of yellowing in human crystalline lens. The intensities of our stimuli were on the asymptote of the intensity-response curve. We performed linear regression analysis against age on the S-cone ERG b-wave (S-b), and the LM- cone ERG a-, b- and d-waves (LM-a, LM-b, LM-d). We found significant age- dependent reduction in the amplitude of S-b, LM-a, and LM-d, significant prolongation in the peak time of LM-b and LM-d, and significant increase in the b/a ratio of the LM-cone ERG, but no significant age correlation between the peak time of S-b and LM-a and the amplitude of the b-wave. Our results provide evidence that age-related changes in S- and LM-cone systems begin in the twenties in humans. Furthermore, a significant increase of the b/a ratio suggests that off-bipolar cells are more vulnerable to aging than on-bipolar cells.