Outflow facilities through Descemet's membrane in rabbits.
BACKGROUND
The outflow pathway in viscocanalostomy, a new procedure in glaucoma surgery, is unclear; however, outflow through Descemet's membrane has been postulated. This study evaluates outflow rates through Descemet's membrane at different IOP levels in rabbits.


METHODS
51 Descemet's membranes without endothelium from enucleated rabbit eyes were installed in a double-ring system, the Minuth sheet. Different intraocular pressure levels (20, 25, 30, 40, 50 mmHg) were applied to one side of the system. The system was filled with balanced salt solution. The total amount of fluid percolating through Descemet's membrane was measured after 12 h. Based on this, flow rates were calculated. The area of Descemet's membrane was 6.9 mm2.


RESULTS
At the pressure of 20 mmHg the flow rate was less than 0.003 microl/min. At pressures above 30 mmHg flow rates ranged from 0.04 microl/min to 0.15 microl/min with a mean of 0.09 microl/min. To achieve pressure control at high pressures, an area of at least 150 mm2 of Descemet's membrane would be needed.


CONCLUSIONS
Descemet's membrane provides good outflow resistance in rabbit eyes. Based on our results for pressure control by outflow through Descemet's membrane only, at least the whole corneal area is needed. If the same is true in humans, additional outflow sources are necessary in cases of viscocanalostomy.
Spiegel
Detlev
D
Department of Ophthalmology, University of Regensburg, Germany. Spiegel@eye-regensburg.de
Schefthaler
Marion
M
Kobuch
Karin
K
D000085:Acetates / Q000378:metabolism; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D003886:Descemet Membrane / Q000378:metabolism*; D004338:Drug Combinations; D007429:Intraocular Pressure; D008903:Minerals / Q000378:metabolism; D009799:Ocular Physiological Phenomena; D010477:Perfusion / Q000295:instrumentation; D010539:Permeability; D011312:Pressure; D011817:Rabbits; D012965:Sodium Chloride / Q000378:metabolism
D000085:Acetates; C030660:BSS solution; D004338:Drug Combinations; D008903:Minerals; D012965:Sodium Chloride