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S. Wang, R.A. Linsenmeier; Effects of Hyperoxia on Retinal Metabolism in the Detached Cat Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5256.
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The goal of this study was to investigate the effects of hyperoxia on retinal metabolism in the detached cat retina.
Double barreled oxygen electrodes were used to record PO2 in attached and detached areas of the retina of 9 anesthetized intact cats. A model of oxygen diffusion was fitted to the portion of the oxygen profile in the outer retina. Retinal detachment (RD) was created by injecting healon diluted in balanced salt solution underneath the retina. RD was confirmed by visualization under direct ophthalmoscopy. The diameter of the detachment was 2–5 mm, and the height of the detachment where oxygen profiles were collected was 100–350 µm.
In the detached retina, the PO2 at the outer edge of the retina (P(X=0)) was significantly higher during hyperoxia (100% O2 breathing) than normoxia (air breathing), and reached the same level as in the attached retina under air breathing (control). The PO2 at the border between the inner and outer retina (P(X=L)) was significantly higher under hyperoxia than air breathing in both the detached and attached retina; there was no difference in P(X=L) under air breathing between the detached and attached retina. The average inner retinal PO2 showed a similar result as P(X=L) did. The oxygen consumption of the photoreceptors (Qav) in the detached retina during normoxia was 47% ± 17% of Qav in the attached retina, while hyperoxia increased Qav to 68% ±17% of the value in the attached retina.
The protective effects of hyperoxia reported in previous studies are probably due to the partial restoration of Qav in the detached retina by hyperoxia, which increases PO2 in both the inner retina and at the outer edge of the retina. While the choroid is important in providing increased oxygen, the increased oxygen consumption also depends strongly on increased inner retinal PO2. The incomplete recovery of Qav during hyperoxia, even though the PO2 at the boundaries of the outer retina fully recovered, indicates that there are factors involved in photoreceptor dysfunction during RD in addition to the insufficient supply of oxygen.
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