gms | German Medical Science

104th DOG Annual Meeting

21. - 24.09.2006, Berlin

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Stratus OCT III – An accurate, reliable, novel way to measure central corneal thickness

Meeting Abstract

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  • I. M. Madgula - Department of Ophthalmology Diana, Princess of Wales Hospital Grimsby
  • S. Kotta - Department of Ophthalmology Diana, Princess of Wales Hospital Grimsby

Deutsche Ophthalmologische Gesellschaft e.V.. 104. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft (DOG). Berlin, 21.-24.09.2006. Düsseldorf, Köln: German Medical Science; 2006. Doc06dogP049

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/dog2006/06dog571.shtml

Published: September 18, 2006

© 2006 Madgula et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

Text

Objective

Measurement of corneal thickness is useful for both diagnostic and therapeutic purposes some of which include assessment prior to refractive surgery, corneal changes after extended contact lens wear, reliability of intraocular pressure measurements. The ultrasound pachymeter is the gold standard for Central Corneal Thickness (CCT) measurement.However, with a few modifications the commercially available Stratus OCT III originally designed for posterior segment imaging can be used for CCT measurement.

Aim of the study

To determine the accuracy and reliability of non-contact central corneal thickness (CCT) measurement using a commercially available Stratus OCT III versus standard ultrasound pachymetry and to analyse correlation between CCT measurements using the two devices.

Methods

CCT using Stratus OCT III was taken and averaged. Although this instrument is originally designed for posterior segment imaging, corneal scans can be obtained by minor modifications to the system. The Zeiss system has an integrated high power-condensing lens so that the retina can be imaged onto a plane within the instrument. To image the cornea, the focussing system had to be defocused near the maximum to relay the image of the OCT beam onto the cornea. CCT was then determined using the ultrasound Pachymeter (CCTpach). Data was analysed using SPSS statistical package.

Results

30 white volunteers (12 male, 18 female) participated in this study. Subject age ranged from 30 to 75 years with a mean age of 49.5±18.0 years The mean CCToct was 522.33±34.44.The mean CCTusg was 547.37±33.08.The mean difference between CCTusg and CCToct was 25.04±11.67. CCTpach was found to be highly correlated with CCToct (r 0.93, P<0.001). CCToct=0.980(CCTusg) – 13.90 (r2=0.886 and P<0.001)

Conclusions

OCT is a non contact, non invasive technique that gives reliable readings of corneal thickness. It is easy to perform, and precise positioning of the probe beam is possible due to the video monitor that is assisted by magnification. Control of the patients’ gaze is possible due to the external fixation lights. The ultrasound lacks these advantages and lateral displacement of the probe slightly can give rise to falsely high readings.

Thus the Stratus OCT III is a novel, reliable and accurate way to measure corneal thickness and future generations of OCT may incorporate means to measure CCT with minimal or no modifications to the system.