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Abstract #27505 Published in IGR 12-4
The digital aqueous humor outflow meter: An alternative tool for screening of the human eye outflow facility
Kozobolis VP; Paschalis EI; Foudoulakis NC; Koukoula SC; Labiris GClinical Ophthalmology 2010; 4: 937-945
Purpose: 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's repeatability was evaluated by means of Cronbach'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>0.999). DAHOM demonstrated high repeatability (Cronbach's alpha (greater-than or equal to)0.997; intraclass correlation coefficient (greater-than or equal to)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. (copyright) 2010 Kozobolis et al.
E. I. Paschalis. Eye Institute of Thrace, University Hospital of Alexandroupolis, 68 100 Dragana, Alexandroupolis, Thrace, Greece. epaschalis@hotmail.com
Classification:
6.2 Tonography, aqueous flow measurement (see also 2.6) (Part of: 6 Clinical examination methods)
2.6.2 Outflow (Part of: 2 Anatomical structures in glaucoma > 2.6 Aqueous humor dynamics)
