Trans-scleral tonometry: Mechanical palpation of the eye

Péter P. Polyvás, Eniko T. Enikov, Gholam Peyman, Vasco Polyzoev

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The development of new tonometers requires laboratory tests on enucleated eyes where the intraocular pressure (IOP) is usually controlled by the use of a fluid column (manometry). This article describes a novel eye pressure regulation system for IOP tests along with a new concept of mechanical palpation tonometry. Manometry is commonly regarded as an invasive technique that can measure precisely the pressure inside the eye. It is a common laboratory technique for evaluating changes in IOP over time, and for providing reference pressure by which all other tonometers can be evaluated. In general, the system consists of a fluid column (1 % saline solution) connected via PVC tubing to a three way valve. The valve is able to connect the column branch to a syringe with a 21G needle inserted into the vitreous humor and to a pressure transducer. The syringe needle is inserted in the eye through the side, with the tip located approximately in the middle of the vitreous chamber [1]. However, this method is prone to errors due to the gelatinous and highly fibrous nature of the vitreous matter that could easily clog the syringe needle and prevent the accurate pressure control and measurement. To resolve this difficulty, we report an alternative control of the IOP through the anterior chamber of the eye. In addition to the clogging, severed blood vessels in enucleated eyes result in large rate of leakage of intraocular fluid. With these modifications in place, it was demonstrated that the pressure sensing is fast and accurate, allowing investigation of mechanical trans-scleral palpation and the development of a new concept of mechanical palpation tonometry device. The device is based on multiple probes for measuring contact forces. Experimental data from the performance of the device are presented.

Original languageEnglish (US)
Title of host publicationBiomedical and Biotechnology Engineering; Nanoengineering for Medicine and Biology
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages5
ISBN (Print)9780791854884
StatePublished - 2011
EventASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 - Denver, CO, United States
Duration: Nov 11 2011Nov 17 2011

Publication series

NameASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011


OtherASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011
Country/TerritoryUnited States
CityDenver, CO

ASJC Scopus subject areas

  • Mechanical Engineering


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