Abstract
Abstract
Changes in Oxygen Tension (pO2) in the Rabbit Lens and Vitreous after Vitrectomy
Barbazetto I., Dillon J., Liang J., Spector A., Chang S. Columbia University, E. S. Harkness Eye Institute, New York, USA
Purpose: The purpose of this study was to evaluate the potential role of oxygen in the development of cataract following vitrectomy. Method: Harlan rabbits (3.5 5.3 kg) were anesthetized using ketamin and xylazin (Protocol# 3006.0). Nine measurements in pre-defined positions within the vitreous, the lens and the anterior chamber were performed using a micromanipulator. Oxygen measurements were performed using an optode (Foxy Fiber Optic Oxygen Sensors System/ Oceanoptics, Dunedin, USA) connected to a spectrometer. One eye of each rabbit was vitrectomized using BSS as a vitreous replacement. Follow-up examinations were performed after 2, 4, 6 and 8 weeks in randomized groups. The contra-lateral eye served as a control. Results: The lowest pO2 in the normal rabbit eye was measured within the center of the lens (9.4 mmHg ± 1.2). The posterior lens had a low oxygen tension (10 mmHg ± 0.4) close to the values of the vitreous directly behind the posterior capsule. Within the vitreous there was a small gradient with the highest values close to the larger retinal vessels on the retina. Two weeks after vitrectomy the pO2 values in the lens were 2 to 3 times as high as in the control eye (p < 0.05). The pO2 gradient in the vitreous was not detectable anymore. Eight weeks after vitrectomy, pO2 levels in t
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