Local neuroretinal function during acute hypoxia in healthy older people.

PURPOSE To measure the effect of acute, mild, systemic hypoxia on neuroretinal function in two different age groups. METHODS The slow-flash paradigm of the multifocal electroretinogram (mfERG) was measured in two different oxygenation levels. Twelve participants of two age groups (28 +/- 4 and 55 +/- 5 years) breathed room air (normoxia) or 12% oxygen (hypoxia). RESULTS During normoxia (SaO(2) = 98%) there was a significantly different effect between the younger and older participants on the mfERG positive waveform components (N1P1 amplitudes and P1 implicit times; P < 0.001). Hypoxia (SaO(2) = 90%) significantly decreased N1P1 response density amplitudes in the central retinal field in both groups, with a larger effect in the older group (P < 0.001). There was no significant change in function of the cellular generators of oscillatory potentials (OPs). CONCLUSION The results extend recent findings by showing a greater effect of hypoxia on ON- and OFF-bipolar cell function in healthy older persons than in younger persons, but no effect on OPs during moderate acute hypoxia in either age group.