Accuracy and results of photopic flash electroretinogram performed with skin electrodes in infants

Qualitative and quantitative comparison of ERGs with contact lens and adhesive skin electrodes

PURPOSE

Traditional ERGs recorded using corneal electrodes can be difficult for some patients to tolerate. In the last several years, adhesive skin electrodes have gained in acceptance. In this report we present a qualitative comparison of waveforms as well as a quantitative analysis of correlation of amplitudes and implicit times of simultaneous ERG recordings using contact lens and skin electrodes.

METHODS

89 subjects were included; all were referred for full-field ERG testing for multiple indications. ERGs (obtained according to ISCEV standards) were recorded simultaneously from both eyes with ERG-jet corneal contact lens electrodes and LKC Technologies Sensor Strip adhesive skin electrodes using multi-channel instrumentation (Diagnosys LLC, Espion3). Waveforms, a-wave and b-wave amplitudes and implicit times were compared.

RESULTS

Waveform morphologies were similar between electrode types. Regression coefficients (conversion factors) for a-wave and b-wave amplitudes under both photopic and scotopic conditions were tightly clustered. Regression coefficients for implicit times were nearly equal to 1.0. The regression coefficient for the entire amplitude dataset was 0.349, with an overall correlation of 0. 869 between amplitude recorded with skin and contact lens electrodes. The regression coefficient for the entire implicit time dataset was 0.967, with an overall correlation of 0.964 between skin and contact lens electrodes.

CONCLUSIONS

Our best estimate for the conversion factor between ERG amplitudes recorded with adhesive skin electrodes and contact lens electrodes is 0.349-amplitudes with skin electrodes are about 1/3 the amplitudes recorded simultaneously from the same eyes with contact lens electrodes, with a high correlation. Implicit times are nearly identical for the two electrode types.

Electroretinograms in idiopathic infantile nystagmus, optic nerve hypoplasia and albinism

PURPOSE

To study electroretinograms in infantile nystagmus syndrome associated with idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism.

METHODS

A total of 30 children with idiopathic infantile nystagmus, 18 with optic nerve hypoplasia, and 18 with albinism were studied. Three electroretinogram protocols were applied according to child's age: 58 (mean: 2.0 years) were recorded with skin electrode to Great Ormond Street Hospital protocol, 11 (mean: 5.3 years) with skin electrode to International Society for Clinical Electrophysiology of Vision protocol, and 7 children (mean: 12.2 years) with HK electrode to International Society for Clinical Electrophysiology of Vision protocol. The electroretinograms were compared to those of age-matched controls.

RESULTS

Electroretinogram waveforms in idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism were comparable to controls in all protocols. Electroretinogram amplitudes in idiopathic infantile nystagmus group showed increased white scotopic and photopic electroretinograms in 26 children (skin electrode to Great Ormond Street Hospital protocol), no difference to the controls in 3 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol), and increased rod electroretinogram in 3 children (HK electrode to International Society for Clinical Electrophysiology of Vision protocol). Optic nerve hypoplasia group showed increased white scotopic, photopic, and blue electroretinograms in 15 children (skin electrode to Great Ormond Street Hospital protocol); increased 30-Hz electroretinogram in 3 children (HK electrode to International Society for Clinical Electrophysiology of Vision protocol); and reduced combined rod-cone, cone, and 30-Hz electroretinograms in 3 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol). Albinism group showed increased white scotopic, photopic, and 30-Hz electroretinograms in 17 children (skin electrode to Great Ormond Street Hospital protocol), while it showed reduced cone and 30-Hz electroretinograms in 5 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol). Implicit times were shorter in albinism.

CONCLUSION

Electroretinogram waveforms in idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism were normal with mostly increased electroretinograms, while reduced electroretinograms did not show a specific pattern as in early-onset retinal dystrophies.

Electroretinographic characteristics in children with infantile nystagmus syndrome and early-onset retinal dystrophies

PURPOSE

To differentiate early-onset retinal dystrophies on the basis of electroretinogram (ERG) characteristics in children with infantile nystagmus syndrome (INS).

METHODS

Thirty-seven children with INS and early-onset retinal dystrophies were included, with diagnosis according to clinical and ERG findings. Three ERG protocols were used according to the child's age and 17 children were followed with 2 protocols: 27 (mean 2.1 years) were recorded with skin electrodes to flash stimulation, 16 (mean 6.5 years) with skin electrodes to full-field stimulation, and 11 (mean 12.2 years) with HK electrodes to full-field stimulation. The ERGs were compared to those of age-matched controls, with differences significant if p<0.05.

RESULTS

Clinical and electrophysiologic findings were in agreement across all of the children. In nine children with Leber congenital amaurosis, the scotopic and photopic ERGs were not recordable under all protocols. Six children with congenital stationary night blindness (CSNB) had electronegative scotopic ERG under all protocols, those with complete CSNB had absent rod ERG, and those with incomplete CSNB had reduced rod ERG. Eight children with achromatopsia had nonrecordable photopic and subnormal scotopic ERG under all protocols. The implicit times of the scotopic b-waves were prolonged. One child had blue-cone monochromatism and reduced photopic and normal S-cone ERG. Six children with cone-rod dystrophy without systemic disorder, and seven children with systemic disorder, had affected photopic and scotopic ERGs under all protocols.

CONCLUSIONS

In children with INS, some early-onset retinal dystrophies can be differentiated through ERGs, also with skin electrodes.