ERG responses to full–field stimuli recorded with skin and corneal electrodes in healthy volunteers and in children with retinal dystrophies.

Abstract

Abstract: : Purpose:In healthy volunteers compare ERG responses to full–field stimuli recorded with corneal contact and skin electrodes. Assess ERG responses recorded with skin electrodes in children with retinal dystrophies. Methods:At two centres ISCEV Standard rod and cone ERGs were recorded in a total of 129 healthy volunteers to compare Burian Allen (BA), Gold Foil (GF) and skin electrode responses in adults and children. In Cambridge ERGs were also recorded using skin electrodes in 50 patients aged 4–14yrs with retinal dystrophy. The type of retinal dystrophy was classified on the basis of standard clinical criteria and genetic tests and their ERG responses were compared with those of the age–matched normal children. Results:BA and GF ERG amplitudes and latencies generally did not differ significantly in normal subjects. Technically satisfactory rod and cone responses were also recorded with skin electrodes in every normal subject and the ERG waveforms were similar to recordings obtained with a GF electrode. Responses in adults and children did not differ significantly for either BA or skin electrodes. BA and GF ERGs were 4 to 5 times larger than skin electrode responses. After amplitude scaling the distribution of skin electrode responses was similar to that for corneal electrodes in both adults and children. ERG findings were consistent with the clinical diagnosis in the majority of patients. Rod responses were abnormal in every patient with a rod–cone dystrophy and cone b–wave and 30Hz flicker ERGs were also abnormal in the majority of patients. Those patients with cone dystrophy or rod monochromatism had normal or near normal rod responses but sub–normal or absent cone responses. Patients with CSNB or XLRS had a sub–normal b–wave and normal amplitude a–wave. Conclusions:Full–field ERGs can be recorded successfully with either corneal or skin electrodes in normal subjects. Skin ERG data can also aid diagnosis of the type of retinal dystrophy.

Keywords: electroretinography: clinical • retinal degenerations: hereditary