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Experimental hypoxia in human eyes: Implications for ischaemic disease.

Feigl B, Stewart I, Brown B

Institute of Health and Biomedical Innovation, Queensland University of Technology, Australia; School of Optometry, Queensland University of Technology, Australia.

OBJECTIVE: This study investigated neuroretinal activity under normoxic and hypoxic conditions with the multifocal electroretinogram (mfERG). METHODS: We used two mfERG paradigms, the fast flicker and slow flash stimulation modes, to measure neuroretinal activity in five healthy participants who breathed room air and a reduced oxygen mixture (14% oxygen, balance nitrogen). We analysed concentric ring N1P1 and P1N2 response density amplitudes, the P1 implicit times as well as the local scalar product (SP) response densities. RESULTS: During hypoxia there was a significant reduction of the scalar product response density for the fast flicker (p<0.001) and for the slow flash mfERG (p<0.001). The N1P1 and P1N2 response densities were lower especially for the central three rings; although these reductions were not significant between the two oxygen conditions, they indicated an overall distortion of the mfERG waveform. CONCLUSIONS: It is demonstrated that a postreceptoral, primarily ON and OFF bipolar cell deficit is evident in the central retina of healthy young people during short term hypoxia. SIGNIFICANCE: Our findings suggest that persons with pre-existing ischaemic eye disease may be at risk when exposed to hypoxic conditions.

Published 12 March 2007 in Clin Neurophysiol, 118(4): 887-95.
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