The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility

Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, Stavrenia C Koukoula, Georgios LabirisDepartment of Ophthalmology and Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, GreecePurpose: To develop, characterize, and validate a prototype digital aqueous hu...

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Autores principales:	Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, et al
Formato:	article
Lenguaje:	EN
Publicado:	Dove Medical Press 2010
Materias:	Ophthalmology RE1-994
Acceso en línea:	https://doaj.org/article/51aa759189f04ec8857909973597711c
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spelling	oai:doaj.org-article:51aa759189f04ec8857909973597711c2021-12-02T00:15:36ZThe digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility1177-54671177-5483https://doaj.org/article/51aa759189f04ec8857909973597711c2010-08-01T00:00:00Zhttp://www.dovepress.com/the-digital-aqueous-humor-outflow-meter-an-alternative-tool-for-screen-a5139https://doaj.org/toc/1177-5467https://doaj.org/toc/1177-5483Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, Stavrenia C Koukoula, Georgios LabirisDepartment of Ophthalmology and Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, GreecePurpose: To develop, characterize, and validate a prototype digital aqueous humor outflow tonographer (DAHOM).Material and methods: The DAHOM was developed, characterized, and validated in three phases. Phase 1 involved construction of the sensor. This was broadly based on the fundamental design of a typical Schiotz tonographer with a series of improvements, including corneal indentation, which was converted to an electrical signal via a linear variable differential transducer, an analog signal which was converted to digital via ADC circuitry, and digital data acquisition and processing which was made possible by a serial port interface. Phase 2 comprised development of software for automated assessment of the outflow facility. Automated outflow facility assessment incorporated a series of fundamental improvements in comparison with traditional techniques, including software-based filtering of ripple noise and extreme variations, rigidity impact analysis, and evaluation of the impact of patient age, central corneal thickness, and ocular axial length. Phase 3 comprised characterization and validation of DAHOM, for which we developed an experimental setup using porcine cadaver eyes. DAHOM&rsquo;s repeatability was evaluated by means of Cronbach&rsquo;s alpha and intraclass correlation coefficient. The level of agreement with a standard Schiotz tonographer was evaluated by means of paired t-tests and Bland-Altman analysis in human eyes.Results: The experimental setup provided the necessary data for the characterization of DAHOM. A fourth order polynomial equation provided excellent fit (R square &gt;0.999). DAHOM demonstrated high repeatability (Cronbach&rsquo;s alpha &ge;0.997; intraclass correlation coefficient &ge;0.987) and an adequate level of agreement with a standard Schiotz tonographer.Conclusions: This study presents the development, characterization, and validation of a prototype digital tonographer. DAHOM demonstrates high repeatability and a sufficient level of agreement with a typical Schiotz tonographer, while its digital design remedies known vulnerabilities of conventional tonographers.Keywords: glaucoma, tonography, pressure, outflow facility, aqueous humor Vassilios P KozobolisEleftherios I PaschalisNikitas C Foudoulakiset alDove Medical PressarticleOphthalmologyRE1-994ENClinical Ophthalmology, Vol 2010, Iss default, Pp 937-945 (2010)
institution	DOAJ
collection	DOAJ
language	EN
topic	Ophthalmology RE1-994
spellingShingle	Ophthalmology RE1-994 Vassilios P Kozobolis Eleftherios I Paschalis Nikitas C Foudoulakis et al The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
description	Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, Stavrenia C Koukoula, Georgios LabirisDepartment of Ophthalmology and Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, GreecePurpose: To develop, characterize, and validate a prototype digital aqueous humor outflow tonographer (DAHOM).Material and methods: The DAHOM was developed, characterized, and validated in three phases. Phase 1 involved construction of the sensor. This was broadly based on the fundamental design of a typical Schiotz tonographer with a series of improvements, including corneal indentation, which was converted to an electrical signal via a linear variable differential transducer, an analog signal which was converted to digital via ADC circuitry, and digital data acquisition and processing which was made possible by a serial port interface. Phase 2 comprised development of software for automated assessment of the outflow facility. Automated outflow facility assessment incorporated a series of fundamental improvements in comparison with traditional techniques, including software-based filtering of ripple noise and extreme variations, rigidity impact analysis, and evaluation of the impact of patient age, central corneal thickness, and ocular axial length. Phase 3 comprised characterization and validation of DAHOM, for which we developed an experimental setup using porcine cadaver eyes. DAHOM&rsquo;s repeatability was evaluated by means of Cronbach&rsquo;s alpha and intraclass correlation coefficient. The level of agreement with a standard Schiotz tonographer was evaluated by means of paired t-tests and Bland-Altman analysis in human eyes.Results: The experimental setup provided the necessary data for the characterization of DAHOM. A fourth order polynomial equation provided excellent fit (R square &gt;0.999). DAHOM demonstrated high repeatability (Cronbach&rsquo;s alpha &ge;0.997; intraclass correlation coefficient &ge;0.987) and an adequate level of agreement with a standard Schiotz tonographer.Conclusions: This study presents the development, characterization, and validation of a prototype digital tonographer. DAHOM demonstrates high repeatability and a sufficient level of agreement with a typical Schiotz tonographer, while its digital design remedies known vulnerabilities of conventional tonographers.Keywords: glaucoma, tonography, pressure, outflow facility, aqueous humor
format	article
author	Vassilios P Kozobolis Eleftherios I Paschalis Nikitas C Foudoulakis et al
author_facet	Vassilios P Kozobolis Eleftherios I Paschalis Nikitas C Foudoulakis et al
author_sort	Vassilios P Kozobolis
title	The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
title_short	The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
title_full	The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
title_fullStr	The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
title_full_unstemmed	The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
title_sort	digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility
publisher	Dove Medical Press
publishDate	2010
url	https://doaj.org/article/51aa759189f04ec8857909973597711c
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The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility

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