Spectral sensitivities of mechanisms dominated by short-, middle-, or long-wavelength-sensitive cones were measured for 76 observers ranging in age from 10 to 84 years. The short-wavelength mechanism was isolated with a yellow adapting background and five test wavelengths between 420 and 550 nm modulated at 2 Hz. Sensitivity declined with age, but the slopes of the functions varied as a function of wavelength. When the data were corrected for light losses in the ocular media, the slopes were similar for λ ≤ 500 nm and still significantly correlated with age. At 440 nm, the sensitivity of the short-wavelength mechanism, specified at the retinal level, declined at a rate of 0.08 log unit per decade. Sensitivity at 550 nm under these conditions was dependent on middle- and/or long-wavelength-sensitive cones and was not correlated significantly with age. To study isolated middle- and long-wavelength mechanisms, sensitivities were measured at six wavelengths between 500 and 650 nm, using a 20-Hz test stimulus and appropriate chromatic adapting backgrounds. The sensitivities at all wavelengths were correlated negatively with age. When specified at the retinal level, the sensitivity at 560 nm declined at a rate of 0.11 log unit per decade for both middle- and long-wavelength mechanisms. These data support the view that the sensitivities of all three cone types and/or at least one of their postreceptoral pathways declines from 10 to 84 years of age.
© 1988 Optical Society of AmericaFull Article | PDF Article
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