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Abstract #18479 Published in IGR 3-3
Effect of pneumatic suction ring placement on intraocular pressure in cats
Li BOphthalmic Research 2001; 33: 271-275
PURPOSE: To determine the effect of placing a pneumatic suction ring on intraocular pressure (IOP) in the cat and to design an improved method to generate a stable elevation of IOP. METHODS: A pneumatic suction ring was applied to the eye of cats while IOP was monitored. Three groups of animals (ten per group) were used. A vacuum pressure of 450 mbar was applied in one step to eyes of group 1 (anesthetized) and to group 2 (euthanized) cats. In group 3 (anesthetized) cats, an initial vacuum pressure of 250 mbar was applied, followed by a vacuum of slowly increasing pressure at a rate of 5 mbar/min for a total of 40 minutes to 450 mbar. RESULTS: After the one-step application of a vacuum (450 mbar) to the eyes of anesthetized cats (group 1), IOP peaked within the first minute from a basal value of 25 ± 2 mmHg (mean ± SD) to 90 ± 7 mmHg. It then rapidly decreased to 69 ± 2 mmHg five minutes later, and continued to decrease to 39 ± 4 mmHg 40 minutes later. This sharp peak and decline of IOP were also observed in eyes of euthanized cats (group 2). The basal IOP of these eyes was 8 ± 1 mmHg. It rose to 18 ± 2 mmHg immediately after the application of vacuum pressure (450 mbar) and returned to the basal level five minutes later. In contrast, the eyes in group 3 receiving an initial vacuum of 250 mbar followed by a 5/mbar/min vacuum increment exhibited a rapid increase in IOP and a very stable plateau (mean IOP = 62-68 mmHg), lasting the whole study period (40 minutes). CONCLUSIONS: After a one-step application of a vacuum via a pneumatic suction ring, IOP is self-adjusting and declines rapidly over time. This decline in IOP can be overcome by a supplementary increment in vacuum pressure.
Dr B. Li, Dean A. McGee Eye Institute, University
Classification:
2.16 Chiasma and retrochiasmal central nervous system (Part of: 2 Anatomical structures in glaucoma)