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Catherine Liu, Gowtham Jonna, Jasmine Francis, Brian Marr, David Abramson, Scott Brodie; Non-selectivity of ERG reductions in eyes treated for retinoblastoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3978.
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We have monitored retinal function in patients treated for retinoblastoma (primarily, but not exclusively by intra-arterial chemotherapy infusion) by ERG recordings for the past six years. We here present data from the subset of patients who underwent a complete ERG protocol including both photopic and scotopic recordings to justify our frequent practice of reporting primarily 30-Hz photopic flicker amplitude data.
Patients referred for treatment of retinoblastoma underwent ERG recordings during examination under anesthesia whenever possible at baseline, and following most treatment sessions, especially after intra-arterial chemotherapy. All recordings included photopic single flash (Photopic 3.0, “Phot SF”) and 30-Hz flicker (“Phot 30 Hz”) stimuli; when time permitted, many also underwent dark adaptation for 5 minutes (shorter than the ISCEV standard protocol to minimize anesthesia duration) followed by recordings of responses to scotopic rod-isolating (Scotopic 0.01, “Rod”) and scotopic maximal (Scotopic 3.0, “Scot Max”) flash stimuli. Response amplitudes were measured from averages of 10 replicate records to suppress the effects of unsteady baselines caused by the sevofluorane anesthesia. Correlations were calculated for the complete datasets between the four sets of responses amplitude data.
Complete photopic and scotopic ERG data was available from over 600 ERG studies of 108 patients. The correlation matrix for these ERG responses are detailed in Table I.
Under our recording conditions, ERG responses of eyes with untreated retinoblastoma or following intra-arterial treatment for retinoblastoma show very high correlations between 30-Hz flicker amplitude responses and the three other standard photopic and scotopic ERG response amplitudes. The reductions in ERG amplitudes seen in these eyes do not appear to be selective for rod or cone systems. These observations support the use of photopic response amplitudes (especially in response to 30-Hz flicker) as the primary ERG outcome measure in studies of treated and untreated eyes with retinoblastoma when more complete ERG protocols may be impractical.
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