Modifications of the Goldmann-Weekers adaptometer are described which permit sensitive measurements of visibility thresholds to deep red and deep blue light. The test spots subtend six minutes of arc and fixation is controlled by a movable luminous orange point of light. Consistent measurements, usually made in the vertical meridian, suggest that data obtained with the red test spot represent cone function and data with the blue test spot represent rod function (retinal profiles).
Curves are shown for eyes with normal function, color blindness, night blindness, and central defects. It appears that early damage to the macular area (as in chloroquine phosphate retinopathy) can be assessed by this method before it is observed ophthalmoscopically and before it produces notable losses in visual fields or acuity.
GUNKEL RD. Retinal ProfilesA Psychophysical Test of Rod and Cone Sensitivity. Arch Ophthalmol. 1967;77(1):22-25. doi:10.1001/archopht.1967.00980020024006