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J Liang, I Barazabetto, L Zheng, J Dillon; Oxygen Tension in Rabbit Vitreous and Lens . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2380.
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Purpose: To determine the oxygen tension in the rabbit vitreous and lens and investigate the mechanisms by which it is controlled. Methods: Rabbits (2.5-3kg) were anesthetized and oxygen tension was probed using either a fiber-optic oxygen sensor system (optode) or a Clark polarographic oxygen electrode. In many cases a micromanipulator was employed to ascertain the exact position of the probe within the eye. Results: It was found that 1) with agreement with previous studies, an oxygen tension gradient exits in vitreous body which decreases from the retina towards the anterior vitreous. The gradient is deep near the retina whereas more than 0.5mm away from the retina it is very shallow. 2) There is also an oxygen tension gradient in preretinal vitreous, which decreases from posterior pole towards periphery. 3) Oxygen tension in the lens is asymmetric with the anterior containing some 1.5 times more oxygen than the posterior and oxygen in the posterior being at the same tension as the anterior vitreous. 4) After sacrifice the oxygen tension in the central vitreous dropped precipitously to almost zero after only 10 minutes. 5) Although much of this loss is due to retinal metabolism, this can not explain the very rapid loss, since we found that oxygen diffuses some four times slower in vitreous than in buffer. 6) HPLC analysis showed that losses in oxygen were paralleled by losses in ascorbic acid. Conclusion: Oxygen diffusion is relatively slow in the vitreous so the vitreous can act as a barrier to oxygen. The vitreous can also consume oxygen by chemical mechanisms. Therefore the vitreous body plays a key role in maintaining a low and stable level of oxygen in the vitreous cavity, which is beneficial to the lens. Any disruption of the vitreous, such as in a vitrectomy, will compromise the viability of the lens.
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