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M.C. Brown, R.P. Hagan, M.A. Thomas, A.M. Mackay; Photopic flash ERG B–wave and 30Hz flicker latency under general anaesthesia . Invest. Ophthalmol. Vis. Sci. 2004;45(13):824.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To review photopic flash and 30Hz flicker latency results in children who have undergone ERG tests under general anaesthesia (UGA) and those who undertook the tests whilst awake. We have noticed that tests under general anaesthesia often have considerably increased latencies compared to awake tests. This study tests the validity of this observation and considers the reasons with regard to the stimulator and the anaesthetic. Methods:In our clinic, diagnostic ERG tests are performed on some children under general anaesthesia. ERG tests are performed awake using the LKC UTAS 2000 system with full–size Ganzfeld stimulator and lower lid skin electrodes or gold foil corneal electrodes. UGA these are performed with JET corneal electrodes and the LKC mini–Ganzfeld stimulator. Photopic flash latency was measured to the peak of the B–wave, and 30Hz latency was taken from the LKC flicker latency calculation. From existing diagnostic records: (i) 30Hz response latencies were compared for the UGA group with values from an independent group of awake subjects, (ii) photopic flash B–wave latency was compared in 4 children who had tests both UGA and awake. Also (iii) 8 adult volunteers had flash and flicker tests with skin electrodes to compare latencies using the full–size and the hand–held mini–Ganzfeld stimulator. Results:(i) Mean 30Hz latency for the UGA group (10 cases – OD only) was 33.2ms (SD 3.35), and for the awake group (70 cases) with skin electrodes 26.8ms (SD 2.46) (p<0.05). (ii) Of the four cases tested in both conditions: B–wave latency in ms
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