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Y. Morizane, S. Mohri, M. Nakayama, K. Yamamoto, T. Miyasaka, I. Takasu, S. Takashima, K. Sakai, H. Ohtsuki, K. Naruse; Application of Porous Glass for a New Glaucoma Drainage Device –Optimal Permeability for Intraocular Pressure Reduction . Invest. Ophthalmol. Vis. Sci. 2006;47(13):26.
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© ARVO (1962-2015); The Authors (2016-present)
Implantation of drainage device has been established as a therapy for glaucoma patients. By using porous glass and silicone tube, we propose a novel glaucoma drainage device, which drains aqueous humor to the external surface of the conjunctiva without causing bacterial infection. The objective of the present study is to evaluate water permeability of porous glass and to determine the filtration area needed to reduce intraocular pressure (IOP) effectively.
We assembled modules of the glaucoma drainage device composed of a cylindrical porous glass (5 mm in outer diameter, 4.6 mm in inner diameter, 35 mm in length, 200 nm in pore size, Shirasu Porus Glass, SPG Technology, Miyazaki, Japan) and silicone tube. The filtration area of the module was 505.5 mm2. By draining saline, we measured filtration rate of the module at 10 mmHg, 20 mmHg and 30 mmHg under physiological conditions of the eye (310K, n = 30).
The water permeability of module at each pressure was 37.5 ± 5.4 µl/min at 10 mmHg, 88.1 ± 6.5 µl/min at 20 mmHg and 140.0 ± 7.0 µl/min at 30 mmHg (mean ± SD). The water permeability was proportional to pressure (R2 = 0.98). We estimate that the filtration area needed to obtain optimal permeability, i.e. physiological aqueous humor production rate of 2.5 µl/min at 20 mmHg IOP, is 14.3 mm2. In our calculation, this glaucoma drainage device can reduce IOP from 40 mmHg to 15 mmHg in 60 minutes.
The new drainage device composed of porous glass should be effective in reducing IOP.
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