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Abstract #6319 Published in IGR 3-2
Giant vacuole survival time and implications for aqueous humor outflow
Brilakis HS; Johnson DHJournal of Glaucoma 2001; 10: 277-283
PURPOSE: A quantitative study was conducted to estimate the survival time of giant vacuoles of the endothelial wall of Schlemm's canal once perfusion pressure has dropped to zero. Vacuoles are known to be sensitive to intraocular pressure (IOP) and could serve as real-time markers of aqueous pressure in the juxtacanalicular tissue if their survival time is short once pressure is lowered. METHODS: Six pairs of healthy human eyes were perfused with phosphate-buffered saline. One eye was then fixed by perfusion, whereas the fellow eye was dissected into wedges and fixed by immersion at intervals ranging from three to 120 minutes after perfusion had been stopped. Light microscopy was used to determine the number of giant vacuoles on the inner and outer walls of Schlemm's canal. RESULTS: A 70% decrease in giant vacuole counts was found three minutes after discontinuation of saline perfusion when compared with perfusion-fixed fellow eyes (5.9 ± 4.0 vacuoles per histological section versus 19.1 ± 9.0; p = 0.02). Vacuole counts continued to decrease with time so that by 120 minutes at zero pressure, vacuole counts were 12% of those in the perfusion-fixed eyes (88% decrease; p = 0.003). Giant vacuoles occurred on the inner and outer walls of the canal, but were more numerous on the inner wall. CONCLUSIONS: Most giant vacuoles have a short survival time, less than three minutes, once perfusion pressure decreases to zero. This suggests that they can response rapidly to IOP changes, and can thus serve as markers of aqueous pressure differences across the inner and outer walls of Schlemm's canal.
Dr D.H. Johnson, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
Classification:
2.5 Meshwork (Part of: 2 Anatomical structures in glaucoma)
2.6 Aqueous humor dynamics (Part of: 2 Anatomical structures in glaucoma)