In Vitro Analysis of Pressure Resistance in the Paul Glaucoma Implant and Ahmed ClearPath 250 With and Without Polypropylene Thread Inside the Tube.
Masdipa Andi, Kaidzu Sachiko, Tanito Masaki
AI Summary
This study found inserting polypropylene threads into glaucoma drainage devices significantly increases pressure resistance. A 6-0 thread in PGI may prevent hypotony, while ACP might need a 3-0 thread for adequate resistance.
Abstract
Purpose
Pressure resistance characteristics of the Paul glaucoma implant (PGI) and Ahmed ClearPath 250 (ACP), with and without the insertion of polypropylene thread in their tubes, were evaluated.
Methods
The in vitro flow pressure was evaluated at varying flow rates, both with and without threads (6-0 for PGI and 4-0 or 3-0 for ACP). Cross-sectional areas of the tube lumen and thread were measured to calculate pressure resistance using the Hagen-Poiseuille equation.
Results
For the PGI without the thread, the pressure remained relatively low and constant across all flow rates. In contrast, with the insertion of a 6-0 thread, there was a significant increase in pressure resistance, with the pressure increasing from 7.5 mm Hg at 1 µL/min to 43.8 mm Hg at 5 µL/min. For the ACP, the pressure resistance remained relatively constant across all flow rates without a thread and with either 4-0 or 3-0 threads. However, the pressure was higher with 3-0 threads compared with a 4-0 thread. The actual measured pressures agreed well with theoretical values in the no-thread conditions, but were consistently higher than the theoretical values in the threaded conditions.
Conclusions
Inserting polypropylene threads into the tubes of nonvalved glaucoma drainage devices significantly affects pressure resistance with various degree.
Translational relevance: PGI with a 6-0 polypropylene thread may not require external tube ligation to prevent hypotony, whereas ACP with a 4-0 thread likely requires additional ligation. Using a 3-0 thread in ACP may enhance pressure resistance sufficiently to avoid tube ligation, but this requires careful clinical consideration.
MeSH Terms
Shields Classification
Key Concepts6
In an in vitro flow pressure evaluation, the Paul glaucoma implant (PGI) without a thread maintained relatively low and constant pressure across all flow rates.
In an in vitro flow pressure evaluation, inserting a 6-0 polypropylene thread into the Paul glaucoma implant (PGI) significantly increased pressure resistance, with pressure rising from 7.5 mm Hg at 1 µL/min to 43.8 mm Hg at 5 µL/min.
In an in vitro flow pressure evaluation, the Ahmed ClearPath 250 (ACP) maintained relatively constant pressure resistance across all flow rates without a thread and with either 4-0 or 3-0 polypropylene threads; however, pressure was higher with 3-0 threads compared with 4-0 threads.
In an in vitro flow pressure evaluation, the actual measured pressures in nonvalved glaucoma drainage devices agreed well with theoretical values in no-thread conditions, but were consistently higher than theoretical values in threaded conditions.
Inserting polypropylene threads into the tubes of nonvalved glaucoma drainage devices, specifically the Paul glaucoma implant (PGI) and Ahmed ClearPath 250 (ACP), significantly affects pressure resistance to various degrees.
A Paul glaucoma implant (PGI) with a 6-0 polypropylene thread may not require external tube ligation to prevent hypotony, whereas an Ahmed ClearPath 250 (ACP) with a 4-0 thread likely requires additional ligation; using a 3-0 thread in ACP may enhance pressure resistance sufficiently to avoid tube ligation, but requires careful clinical consideration.
Related Articles5
Wound Healing Response After Bleb-Forming Glaucoma Surgery With a SIBS Microshunt in Rabbits.
Basic ScienceExperimental flow studies in glaucoma drainage device development.
Basic ScienceTrabeculectomy with internal tube shunt: a novel glaucoma surgery.
Clinical TrialGlaucoma Tube Changes After Suture Lysis Assessed by High-Resolution Anterior Segment Optical Coherence Tomography.
Observational StudyThe PAUL Glaucoma Implant in the management of uveitic glaucoma-3-year follow-up.
Cohort StudyIs this article assigned to the wrong chapter(s)? Let us know.