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Polymeric Micro Check Valve for Glaucoma Treatment
Considering Rate of Aqueous Humor Formation
Chang-Ju Park
1
, Jaekwon Lee
2
, Byungphil Mun
3
, Jae-Yong An
4
, Seunghwan Moon
2
,
and Jong-Hyun Lee
1,2
1
Department of Medical System Engineering, Gwangju Institute of Science and Technology, Gwangju,
Republic of Korea
2
School of Mechatronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
3
Production Engineering Research Institute, LG Electronics, Seoul, Republic of Korea
4
Future Device R&D Department New Device Team, LG Electronics, Seoul, Republic of Korea
Keywords: Glaucoma Drainage Device, Intraocular Pressure, Micro Check Valve, Polymeric, Cracking Pressure,
Aqueous Humor Formation.
Abstract: This paper describes a novel glaucoma drainage device (GDD) to regulate intraocular pressure (IOP)
considering the rate of aqueous humor formation. The device functionally consists of a polymeric cannula
(silicone tube) and a micro check valve (PDMS: polydimethylsiloxane). The check valve has three layers: a
top layer (cover), which has rounded edges to reduce fibrosis, an intermediate layer (thin movable valve
membrane), and a bottom layer (base plate). A feedforward channel is employed in the top layer to prevent
reverse flow by compensating the pressure of the outlet channel. The thickness of thin the PDMS membrane
was determined considering the cracking pressure and the rate of aqueous humor formation. The cracking
pressure in-vitro test was conducted at 15 mmHg, which lies within the normal intraocular pressure range (10
~ 20 mmHg). The experimental mean value and standard deviation of the flow rate at the cracking pressure
was 2.18 ± 0.69 µL/min, which is confirmed to cover the rate of aqueous humor formation in the normal
human eye (1.5 ~ 3.4 µL/min). Flow in a reverse direction was not observed.
1 INTRODUCTION
Glaucoma is an eye disorder associated with
abnormally increased intraocular pressure (IOP) due
to occlusion of Schlemm’s canal. It permanently
induces resultant visual field loss and progressive
blindness by damaging the optic nerve system. Three
types of glaucoma treatment methods are mainly
used to lower the IOP, including medication, laser
surgery, and glaucoma surgery depending on the
severity. One of the methods of refractory glaucoma
treatment is a drainage device to surgically lower the
IOP (Shuchi and Louis, 2010). Many researchers
have worked to develop such a drainage device for
glaucoma patients. Typically, Molteno, Krupin,
Baerveldt, and Ahmed valves are commercially
available devices, which usually consist of two
components, namely, a cannula and a base plate. The
plate is fixed onto the cornea with sutures, and the
cannula shunts aqueous humour from the anterior
chamber into the reservoir (Brian A Francis et al.,
1998).
Recently, many efforts to develop a drainage
device using microfabrication technologies, called
microelectromechanical systems (MEMS), have
taken advantage of size reduction and batch
processes. In particular, micro check valves are
effective drainage valves for glaucoma patients,
because they easily control the cracking pressure for
regulation of the intraocular pressure and effectively
prevent unexpected reverse flow and/or dust from
outside the eyeball. However, unsuitable device
shapes, such as sharp edges of the plate and cannula,
and non-biocompatible materials can cause failures,
such as inflammatory reactions. Also, the
complicated fabrication of the valve membrane (for
instance, using gray-scale photomask or through-
hole process) might induce a severe variance in
cracking pressure and/or flow rate (Jeffrey Chun-Hui
Lin et al., 2010), (Seunghwan Moon et al., 2012).
This paper presents a novel glaucoma drainage
device (GDD) with a micro check valve, whose flow
64
Park C., Lee J., Mun B., An J., Moon S. and Lee J..
Polymeric Micro Check Valve for Glaucoma Treatment - Considering Rate of Aqueous Humor Formation.
DOI: 10.5220/0004244200640067
In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2013), pages 64-67
ISBN: 978-989-8565-34-1
Copyright
c
2013 SCITEPRESS (Science and Technology Publications, Lda.)