Background Inner retinal oxygenation response (Delta PO2) is a worldwide study focus However, the relevant reports on its radiological measurments are limited In this study, magnetic resonance imaging (MRI), employing Ti weighted image (T1WI), was used to detect changes in Delta PO2 following 100% oxygen inhalation in human subjects Methods MRI was performed on a 1 5-T GE scanner system After obtaining ophthalmologic data, eleven healthy individuals were given room air and 100% oxygen inhalation in order with different intervals The MRI T1WI data were collected for 50 minutes Data were analyzed with NIH IMAGE software Results Delta PO2 was not panretinally uniform, and changes in oxygenation response were spatially inhomogeneous During the initial phase (before 5 minutes) of 100% oxygen inhalation, preretinal vitreous water signals in the region of papilla optica increased rapidly On the contrary, in other regions signals declined In a later period (35 minutes), Delta PO2 was panretinally fluctuated and increased slowly and attained homeostasis After hyperoxia (45 minutes), delayed-enhancement of preretinal vitreous water signals in regions other than the papilla optica occurred, and then dropped down There was no significant difference (P > 0 05) at any consecutive time point during and after hyperoixa Conclusions These results reveal that hyperoxia can induce region-specific signal changes in preretinal vitreous water Regulatory activity of the retinal vessel network may be the mechanism during 100% oxygen inhalation Moreover, MRI is a valuable tool for investigating Delta PO2 and exploring the mechanism of retinal oxygenation response physiologically or pathologically in two Chin Med J 2010,123(22) 3277-3281