Hyperoxia improves oxygen consumption in the detached feline retina

PURPOSE. To investigate the effects of hyperoxia on retinal oxygenation and oxygen consumption in the detached feline retina. METHODS. Retinal detachment was created in nine intact anesthetized cats by injecting 0.25% sodium hyaluronate in balanced salt solution into the subretinal space. Oxygen microelectrodes were used to collect spatial profiles of retinal Po₂ in both the attached and detached retina. A diffusion model was fitted to quantify photoreceptor oxygen consumption (Q_av). RESULTS. In the detached retina, the Po₂ at the border between the retina and the fluid layer under the retina decreased; hyperoxia increased it to a level that was not significantly different from the control (attached retina, air breathing). Detachment did not change the Po₂ at the border between the avascular and vascularized retina; hyperoxia significantly increased the level. Oxygen consumption decreased to 47% ± 18% of the control value in the detached retina during normoxia; hyperoxia increased Q_av to 68% ± 17% of control. Hyperoxia increased the average inner retinal Po ₂ (P_IR) in the detached retina to a level higher than that during normoxia. Detachment did not change P_IR during normoxia. CONCLUSIONS. Hyperoxia has been shown to improve photoreceptor survival in the detached retina. The present work suggests that hyperoxia is protective because it allowed increased photoreceptor oxygen consumption. Whereas normal Po ₂s were maintained at the inner and outer border of the avascular region during hyperoxia, Q_av was not restored to normal, suggesting that other factors are involved in photoreceptor dysfunction during detachment in addition to insufficient oxygen delivery.