Yonago Acta medica 1991;34:131-142

Monochromatic Flash Early Receptor Potential in Dichromats

Akihiko Tamai, Atsushi Yamasaki, Kazunori Shimada, Yuji Sasaki, Hiroshi Nakao, Masao Nagata and Hidefumi Wada*

Department of Ophthalmology, Faculty of Medicine, Tottori University, Yonago 683 and *Department of Ophthalmology, Kochi Medical School, Nankoku 783, Japan

The human monochromatic flash early receptor potential (ERP) is generated in the outer segments of the red-, green- and blue-sensitive cones and is closely coupled with the respective visual pigments erythrolabe, chlorolabe and cyanolabe under the experimental conditions hereinafter. The monochromatic flash ERP was studied in 16 dichromats: 6 protanopes (12 eyes) and 10 deuteranopes (20 eyes). Of the used interference filters, the maximal wavelength, the maximal transmission ratio of wavelength, and the width of wavelength at the half of the maximal transmission ratio were 600 nm, 46% and 12 nm for the red flash ERP (No. 21); 532 nm, 43% and 13 nm for the green flash ERP (No. 14); and 457.5 nm, 48% and 14.5 nm for the blue flash ERP (No. 7), respectively. The ERP amplitude was measured between the peaks of the initial cornea-positive phase (R₁) and the later cornea-negative phase (R₂). Mean amplitudes of the red flash ERP and green flash ERP were very significantly decreased in the protanopes (P < 0.001) and deuteranopes (P < 0.001), in comparison with the corresponding data for 10 normal subjects (20 eyes). The mean amplitude of the blue flash ERP amplitude to the red flash ERP amplitude showed a highly significant increase in the protanopes (P < 0.001) and a highly significant decrease in the deuteranopes (P < 0.001), compared with the mean ratio in the normal subjects, indicating a useful index for the objective clinical detection of congenital red-green color defects.

Key words: deuteranopes; early receptor potential (ERP); monochromatic flash; protanopes; visual pigments

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