TY - JOUR

T1 - Comparison of two prototypes of a magnetically adjustable glaucoma implant in rabbits

AU - Schwerk, Birthe

AU - Harder, Lisa

AU - Windhövel, Claudia

AU - Hewicker-Trautwein, Marion

AU - Wagner, Anna

AU - Bach, Jan Peter

AU - Voigt, Lena Carolin

AU - Hinze, Ulf

AU - Chichkov, Boris

AU - Haferkamp, Heinz

AU - Lubatschowski, Holger

AU - Nikolic, Stephan

AU - Nolte, Ingo

N1 - Funding Information: The study was funded by the Bundesministerium für Wirtschaft und Energie (Federal Ministry for Economic Affairs and Energy) under their Zentrales Innovationsprogramm Mittelstand (ZIM, The Central Innovation Programme). The publication was supported by the Deutsche Forschungsgemeinschaft and University of Veterinary Medicine Hannover, Foundation within the funding programme Open Access Publishing. BS was the recipient of a scholarship from the "Studienstiftung des deutschen Volkes (German academic scholarship foundation)". The funder provided support in the form of salaries for authors [LH, J-PB, CW], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section. The funder only provided financial support in the form of authors' salaries. Two authors (HL & SN) show commercial affiliation (ROWIAK GmbH & Augenärzte am Aegi), respectively, but commissioned nothing.

PY - 2019/4/11

Y1 - 2019/4/11

N2 - Glaucoma drainage devices are used in surgical glaucoma therapy. Success of controlling the intraocular pressure is limited due to fibrous implant encapsulation and fibrin coating on the implant which lead to drainage obstructions. An innovative implant with a magnetically adjustable valve was developed. The valve opening of the implant should eliminate inflammatory products from the outflow area and affect fibrous tissue formation to achieve a sufficient long-term aqueous humour outflow. Lifting of this valve should disturb cell adhesion by exerting mechanical forces. Before testing this hypothesis, the flow characteristics of glaucoma drainage devices, especially the outflow resistance by regular IOP, should be considered in a pilot study, as they are important in preventing too low postoperative intraocular pressure known as ocular hypotony. Therefore, two prototypes of the innovative implant differing in their valve area design were examined regarding their flow characteristics in a limited animal experiment lasting two weeks. Ten healthy New Zealand White rabbits were divided into two groups (A & B) with different implanted prototypes. Daily, tonometry and direct ophthalmoscopy were performed to assess the intraocular pressure and the inflammatory reaction of the eye. After two weeks, the rabbits were euthanised to evaluate the initially histological inflammatory reaction to the implant. In group A, one case of hypotony emerged. When considering the entire observation period, a highly statistically significant difference between the intraocular pressure in the operated eye and that in the control eye was detected in group A (p < 0.0001) in contrast to group B (p = 0.0063). The postoperative inflammatory signs decreased within two weeks. Histologically, a typical but low level foreign body reaction with macrophages and lymphocytes as well as mild to moderate fibrosis was seen after the short experimental period. Based on our tonometric results, prototype B seems to be the system of choice for further research assessing its long-term function and biocompatibility.

AB - Glaucoma drainage devices are used in surgical glaucoma therapy. Success of controlling the intraocular pressure is limited due to fibrous implant encapsulation and fibrin coating on the implant which lead to drainage obstructions. An innovative implant with a magnetically adjustable valve was developed. The valve opening of the implant should eliminate inflammatory products from the outflow area and affect fibrous tissue formation to achieve a sufficient long-term aqueous humour outflow. Lifting of this valve should disturb cell adhesion by exerting mechanical forces. Before testing this hypothesis, the flow characteristics of glaucoma drainage devices, especially the outflow resistance by regular IOP, should be considered in a pilot study, as they are important in preventing too low postoperative intraocular pressure known as ocular hypotony. Therefore, two prototypes of the innovative implant differing in their valve area design were examined regarding their flow characteristics in a limited animal experiment lasting two weeks. Ten healthy New Zealand White rabbits were divided into two groups (A & B) with different implanted prototypes. Daily, tonometry and direct ophthalmoscopy were performed to assess the intraocular pressure and the inflammatory reaction of the eye. After two weeks, the rabbits were euthanised to evaluate the initially histological inflammatory reaction to the implant. In group A, one case of hypotony emerged. When considering the entire observation period, a highly statistically significant difference between the intraocular pressure in the operated eye and that in the control eye was detected in group A (p < 0.0001) in contrast to group B (p = 0.0063). The postoperative inflammatory signs decreased within two weeks. Histologically, a typical but low level foreign body reaction with macrophages and lymphocytes as well as mild to moderate fibrosis was seen after the short experimental period. Based on our tonometric results, prototype B seems to be the system of choice for further research assessing its long-term function and biocompatibility.

UR - http://www.scopus.com/inward/record.url?scp=85064275067&partnerID=8YFLogxK

U2 - 10.1371/journal.pone.0215316

DO - 10.1371/journal.pone.0215316

M3 - Article

C2 - 30973952

AN - SCOPUS:85064275067

VL - 14

JO - PLOS ONE

JF - PLOS ONE

SN - 1932-6203

IS - 4

M1 - e0215316

ER -