Three adults with macular dysfunction and peripheral pigmentary retinal degeneration are described as one clinical entity called progressive cone-rod degeneration, based on their psychophysical and electrophysiological findings. These patients had diminishing visual acuity, abnormal color vision, monophasic dark-adaptation curves with slightly elevated rod thresholds, and markedly decreased or absent cone components in the presence of reduced rod components in the electroretinogram (ERG). Scotopic luminosity curves and ERGs with scotopically balanced lights suggest that the rhodopsin present has a normal absorption spectrum. Cone-rod degeneration is differentiated from dominanty inherited retinitis pigmentosa although both are associated with bone spicule pigmentation and retinal arteriolar attenuation. A recessive mode of inheritance is suggested, and the relationship of cone-rod degeneration to the retinal manifestations of the Laurence-Moon-Biedl syndrome is discussed.
Berson EL, Gouras P, Gunkel RD. Progressive Cone-Rod Degeneration. Arch Ophthalmol. 1968;80(1):68-76. doi:10.1001/archopht.1968.00980050070010