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Goldmann and error correcting tonometry prisms compared to intracameral pressure.
Sean McCafferty1,2,3,4, Jason Levine5,6, Jim Schwiegerling5,7
1Department of Ophthalmology, Intuor Technologies, University of Arizona- College of Medicine, University of Arizona- College of Optical Science, LLC 6422 E. Speedway Blvd. Suite 100, Tucson, AZ, 85710, USA. sjmccafferty66@hotmail.com.
BMC Ophthalmology
|January 6, 2018
Summary
The Correcting Applanation Tonometry Surface (CATS) prism offers more accurate intraocular pressure (IOP) measurements than the Goldmann applanation tonometer (GAT) prism, especially in thin or less rigid corneas.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Medical Device Technology
Background:
- Goldmann applanation tonometer (GAT) is a standard for intraocular pressure (IOP) measurement.
- Corneal properties can significantly influence IOP readings.
- A novel Correcting Applanation Tonometry Surface (CATS) prism aims to improve IOP measurement accuracy.
Purpose of the Study:
- To compare the accuracy of the CATS prism against the GAT prism in measuring intraocular pressure (IOP).
- To evaluate the performance of both prisms in vivo and in vitro across varying corneal properties.
Main Methods:
- Intracameral IOP was measured using a pressure transducer in 58 eyes during cataract surgery.
- Perkins tonometry with both GAT and CATS prisms was used to measure IOP at 10, 20, and 40 mmHg.
- Repeatability was assessed using human cadaver eyes, and results were correlated with central corneal thickness (CCT) and corneal resistance factor (CRF).
Main Results:
- The CATS prism demonstrated closer measurements to true intracameral IOP (1.7±2.7 mmHg difference) compared to the GAT prism.
- Measurement differences were more pronounced in eyes with thin CCT (2.7±1.9 mmHg) and low CRF (2.8±2.1 mmHg).
- No significant difference in measurement repeatability was observed between the two prisms.
Conclusions:
- The CATS prism significantly enhances the accuracy of IOP measurement compared to true intracameral pressure.
- CATS prism shows superior accuracy over GAT, particularly in eyes with thin and less rigid corneas.
- In vivo and in vitro findings validate mathematical models regarding GAT and CATS prism performance.
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