• The diagnosis of cone-rod dysfunction is made with the electroretinogram (ERG). Characteristically, the photopic ERG is worse than the scotopic ERG, and both are abnormal. Of a larger group of patients with retinal dystrophy, 20 cases of cone-rod dysfunction were identified. All patients had progressive disease, and all three main modes of inheritance were represented. There was remarkable similarity of findings among all patients, including temporal disc atrophy, telangiectasia of disc vessels, and little to no pigmentary retinal changes. Patients were not night-blind unless advanced disease was present. These patients suggest that neither telangiectasia nor temporal optic atrophy is pathognomonic for Leber's optic neuropathy nor dominant optic atrophy, respectively. Using a combination of electrophysiologic testing, fundus changes and modes of inheritance may prove helpful in better classifying the different types of retinal dystrophies, including retinitis pigmentosa.
Heckenlively JR, Martin DA, Rosales TO. Telangiectasia and Optic Atrophy in Cone-Rod Degenerations. Arch Ophthalmol. 1981;99(11):1983-1991. doi:10.1001/archopht.1981.03930020859009