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Daphne L McCulloch, Mark Borchert, Pamela Garcia-filion, Ruth Hamilton, Maria Matar, Carly Stewart; Repeated measures comparison of chloral hydrate and propofol effects on flash electroretinograms (ERGs) and pattern ERGs (PERGs). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):482. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Chloral hydrate and propofol are regularly used to allow ocular examination and physiologic testing in young children. Their effects on ERG generators are not fully understood. We compared the effects of these two drugs on ERGs and PERGs in a cohort of young children.
ERGs to light-adapted, standard, full-field flashes and to pattern-reversal (PR) were recorded with cycloplegia in 9 participants enrolled in a prospective study of optic nerve hypoplasia (3 unilateral). At the first session, with chloral hydrate the age range was 8-23 mo; at the second session with propofol it was 20-29 mo. PR stimuli were: 0.9 deg transient checks (1Hz) and 0.8 and 10 degree checks presented at a steady state (ss) rate (16.7 Hz). Examiners masked to the methods measured the ERGs for longitudinal, paired comparisons between the sessions.
Children were 10 mo older at the second session (range 4-15 mo). Full-field ERG amplitudes did not differ between sessions; peak times for a-, b- and i-waves were slower at the second session (propofol) by clinically insignificant amounts (<2ms). Transient PERGs were larger with a slower P50 in the second session (propofol) than with chloral hydrate (P50 3.0 vs 4.7μV, p=0.01 and 43 vs 52ms, p=0.001; N95 4.0 vs 6.1μV, p=0.003). For ssPERGs, the fundamental (f1) to 0.8 degree checks and the 3rd harmonic (f3, 50Hz) to 10 degree checks were larger with propofol than previously with chloral hydrate (1.1 vs 0.75μV, p=0.05 and 0.19 vs 0.11μV, p=0.01, respectively). Except for the enhanced f3, these differences were greater with larger age gaps between sessions; laterality and severity of ONH were not significant confounders.
Conclusions: Light-adapted flash ERG waveforms were similar with chloral hydrate and with propofol in spite of a difference in age ranges between the sessions. The larger PERG amplitudes, found in the second session (propofol) could reflect the expected maturation of the PERG generators, the macula-driven ganglion cells. However, the prolonged P50 peak is not an expected maturation effect and the larger ssPERG at f3 was not associated with the duration of the age gap. Chloral hydrate and propofol had approximately equal effects on light-adapted ERG and PERG generators but we do not rule out that some differences in the ERG waveforms may be drug related.
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