Effect of Corneal Stiffening on Goldmann Applanation Tonometry and Tono-Pen Measurements in Canine Eyes

Tang, Junhua; Pan, Xueliang; Weber, Paul A.; Liu, Jun

doi:10.1167/iovs.11-8516

Cited by 11 publications

(8 citation statements)

References 22 publications

(30 reference statements)

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“…It is possible, with a careful understanding of these errors, to improve applanation tonometry accuracy in both overall bias and errors due to patient variability such as CCT. Additionally, this improved accuracy may translate into added benefits to both pediatric populations and veterinary applications in which these errors appear magnified [ 13 , 15 , 23 ].…”

Section: Discussionmentioning

confidence: 99%

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Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo

McCafferty¹,

Levine

Schwiegerling

et al. 2017

BMC Ophthalmol

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Background: Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. Methods: Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. Results: The Goldmann-type tonometer error measured on live human eyes was 5.2 +/−1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/− 2.3 mmHg lower in the supine position (p < .05). CCT also indicated a sloped correlation to error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/−2. 5 mmHg lower than intracameral IOP in the upright position and 5.4+/− 3.1 mmHg in the supine position (p < .05).

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Section: Discussionmentioning

confidence: 99%

“…Twenty one (21) enucleated human globes were obtained from the Georgia Eye Bank (Atlanta, GA). The whole globes were shipped less than 24 h post-mortem and stored at 4 °C in Optisol chambers until use [ 15 ]. All corneas were of corneal transplant quality without prior surgery.…”

Section: Methodsmentioning

confidence: 99%

Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo

McCafferty¹,

Levine

Schwiegerling

et al. 2017

BMC Ophthalmol

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“…Fifty eight (58) eyes (from 48 patients) aged 18 and older and were enrolled from the Arizona Eye Consultants clinic. A sample size of fifty eight (58) eyes was determined sufficient to demonstrate statistical correlation from previous studies [ 13 – 15 , 17 , 18 ]. The prospective study enrolled patients scheduled for phacoemulsification, cataract surgery.…”

Section: Methodsmentioning

confidence: 99%

“…Twenty one (21) enucleated human globes were obtained from the Georgia Eye Bank (Atlanta, GA). The whole globes were shipped less than 24 h post-mortem and stored at 4 °C in Optisol chambers until use [ 18 ]. All corneas were of corneal transplant quality without prior surgery.…”

Section: Methodsmentioning

confidence: 99%

“…The globe elevation at the central cornea was maintained equal in all measurements to insure a constant intracameral IOP. IOP measurements were completed only at a single intracameral pressure for each globe [ 18 ]. The needle IV tube was connected to a manometric transducer (Dwyer Instruments, Michigan City, IN), an isotonic sodium chloride solution infusion bottle, and an open-air reference tube.…”

Section: Methodsmentioning

confidence: 99%

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Goldmann and error correcting tonometry prisms compared to intracameral pressure

et al. 2018

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BackgroundCompare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro.MethodsPressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability.ResultsThe CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/−2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/−1.9 mmHg) and low resistance (CRF) corneas (2.8+/−2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms.ConclusionA CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.

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Non-continuous measurement of intraocular pressure in laboratory animals

Millar

Pang

2015

Experimental Eye Research

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Effect of Corneal Stiffening on Goldmann Applanation Tonometry and Tono-Pen Measurements in Canine Eyes

Abstract: This study provided experimental evidence that corneal stiffening significantly increases GAT and Tono-Pen readings in canine eyes. Noninvasive ultrasound measurement of acoustic impedance may be used to evaluate corneal stiffness and improve the accuracy of clinical measurements of IOP.

Cited by 11 publications

References 22 publications

Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo

Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo

Goldmann and error correcting tonometry prisms compared to intracameral pressure

Non-continuous measurement of intraocular pressure in laboratory animals

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