Blue light-emitting diode built-in contact lens electrode can record human S-cone electroretinogram

Purpose. To develop a contact lens electrode with a built-in blue light- emitting diode (LED) to record the electroretinogram from short-wave sensitive-cone (Scone) electroretinogram (ERG) in humans. Methods. The ERG was recorded using the blue LED (450 nm) built-in electrode under a yellow background illumination from a slide projector in five normal subjects, a patient with blue cone monochromatism, and a patient with fundus albipunctatus. For comparison, the ERG was also recorded using a yellow LED (566 nm) built-in electrode under the same background illumination in the normal subjects. Results. The amplitude and the peak time of the b-wave recorded with 3-Hz blue stimuli were 5.1 to 12.4 μV and 63 to 68 msec, respectively in normal subjects, 7.3 μV and 65 msec in the patient with blue cone monochromatism, and 11.4 μV and 65 msec in the patient with fundus albipunctatus. Normal subjects responded to neither 30-Hz blue stimuli nor 3- Hz yellow stimuli. Conclusions. Results indicate that the b-wave recorded with 3-Hz blue stimuli is elicited from the S-cone system. This simple technique is useful for testing the human blue cone system.