Two additional benefits of dark glasses on rod vision in patients with congenital achromatopsia.

The visual performance of nine rod monochromats was measured with photopic stimuli viewed through filters that attenuated the ambient illuminance. In kinetic perimetry experiments, eight of nine patients showed substantially larger visual field size under the experimental as compared to the control conditions. In increment threshold or brightness-matching experiments, long wavelength sensitivity was shown to be enhanced under the experimental conditions.