Comparison of IOP measurement using GAT and DCT in patients with penetrating keratoplasties

Ismail, A R; Lamont, M; Perera, Shamira; Khan-Lim, Doreen; Mehta, Rajnikant; MacLeod, J D A; Anderson, David F.

doi:10.1136/bjo.2006.099564

Cited by 19 publications

(15 citation statements)

References 10 publications

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“…Our post-keratoplasty eyes did not show any statistically significant relationship between CCT and both tonometers IOP readings, which is in accordance to previous studies regarding GAT in post-PK, 8,11 post-deep anterior LK, 8 and post-DSEK. 9 It is likely that keratoplasty may alter corneal biomechanics, 9 and Figure 2 Bland-Altman plots of the agreement between GAT and iCare IOP measurements.…”

Section: Discussionsupporting

confidence: 81%

“…3,4,[7][8][9] Studies have shown erroneous postoperative IOP readings with GAT after keratoplasty. [8][9][10][11] Although not fully understood and predictable, GAT IOP errors in corneal grafts may be due to several factors including the following: surgically induced thinning or thickening of the cornea; high and/or irregular postoperative astigmatism; disruption of the mechanical integrity and remodeling of corneal tissue, which include the compliance forces present in the host eye, variable graft-host interface mechanics, changes in corneal biomechanical properties, and difficulties in aligning the tonometer head properly on the corneal surface. [8][9][10][11] Several alternative tonometers have been developed that claim to provide measurements that are not influenced by corneal properties, unlike GAT.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Salvetat

Zeppieri

Miani

et al. 2011

Eye

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Purpose To compare intraocular pressure (IOP) measurements with Goldmann applanation tonometry (GAT) and iCare tonometry in normal and post-keratoplasty corneas and to assess the influence of central corneal thickness (CCT), corneal curvature (CC), and corneal astigmatism (CA) on IOP. Methods This prospective cross-sectional study included one eye of 101 subjects with normal corneas (58 healthy subjects, 43 glaucoma); and 90 post-keratoplasty patients: 34 penetrating keratoplasties (PK); 20 automated-lamellar-therapeutic keratoplasties (ALTK); 19 Descemet-stripping-automatedendothelial keratoplasties (DSAEK); 17 edematous grafts. All subjects underwent GAT and iCare IOP measurements in random order, and CCT, CC, and CA evaluation. The Bland-Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, CC, and CA on IOP.Results iCare significantly underestimated IOP in all groups compared with GAT (GAT minus iCare of 3.5±3.5 mm Hg, Po0.001), but overestimated IOP in the edematous grafts (GAT minus iCare of À6.5 ± 1.9 mm Hg, Po0.001). In normal corneas, both tonometer measurements were directly related to CCT values; iCare readings appeared inversely related to CC. There was no significant relationship between IOP and CCT, CC and CA in post-keratoplasty eyes, except between CC and iCare measurements for PK eyes. Conclusions The agreement between GAT and iCare was clinically acceptable in control, ALTK and DSAEK groups, and poor in PK and edematous grafts eyes. In normal corneas, GAT was significantly affected by CCT; iCare was influenced by CCT and CC. The iCare appeared less influenced by corneal edema when compared with GAT. High IOP readings taken with both tonometers in grafts should raise suspicion of true elevated IOP.

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Section: Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Salvetat

Zeppieri

Miani

et al. 2011

Eye

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“…In keratoconus patients, GAT IOP seems to be 5.3±2.2 mmHg lower than that yielded by non-applanation tonometry, which seemed to provide measurements closer to the true IOP. 20 Ismail et al 19 reported that in eyes that had undergone penetrating keratoplasty, GAT measurements may be less precise than non-applanation tonometry. Meyenberg et al 21 suggested that GAT could slightly underestimate IOP in postkeratoplasty eyes (3.1±2.5 mm), a fact which was confirmed in cases in which the procedure preserves the deeper corneal layers.…”

Section: Applanation Tonometers Goldmann Tonometer (Haag Streit Koenmentioning

confidence: 99%

“…In keratoconus, high astigmatism, and stromal scarring, GAT may show greater variability and lower accuracy. [17][18][19] Brooks et al 18 found that GAT measurements yielded significantly lower values at the apex of the cone when compared to flatter or thicker areas of the cornea, which resulted in an overall underestimation of the true IOP. In keratoconus patients, GAT IOP seems to be 5.3±2.2 mmHg lower than that yielded by non-applanation tonometry, which seemed to provide measurements closer to the true IOP.…”

Section: Applanation Tonometers Goldmann Tonometer (Haag Streit Koenmentioning

confidence: 99%

“…32 In eyes that had undergone keratoplasty and refractive surgery, DCT seems to be less influenced by changes in corneal properties following these procedures. 19,25,74 As a digital tonometer with an automated IOP qualitycheck, together with the increasing evidence of being largely independent of corneal properties, Pascal tonometry seems to be a promising tool for IOP determination in different pathological conditions in clinical practice.…”

Section: Dynamic Contour Tonometry -Pascal Tonometer (Smt Swiss Micromentioning

confidence: 99%

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Modalities of Tonometry and their Accuracy with Respect to Corneal Thickness and Irregularities

Moraes

Prata

Liebmann

et al. 2008

Journal of Optometry

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Recent advances in tonometry have led to the development of a number of devices with differing clinical applications. Their role in cases of abnormal corneal thickness and surface irregularities is particularly important, as inaccurate estimation of the true intraocular pressure (IOP) in such cases may lead to suboptimal evaluation. The purpose of the present review was to evaluate the accuracy of the most widely used devices in cases of corneal thickness and surface irregularities, based on a survey of the published literature. The analysis was based on a Medline search focusing mainly on papers that have evaluated the devices' accuracy with respect to corneal thickness and irregularities. Nine device types (Goldmann tonometer, Tono-Pen, Perkins tonometer, Ocular Response Analyzer, non-contact tonometer, pneumatonometer, I-Care rebound tonometer, Pascal dynamic contour tonometer (DCT) and Phosphene tonometer) were described in detail. Moreover, the physical principles and major utility of each tonometer were compared. Each of the many different commercially available tonometers has specific advantages and disadvantages. New non-invasive technologies are getting closer to a precise estimation of the true IOP. However, among all tonometers, none is highly accurate when both corneal thickness and surface irregularities are present. Fifty years after its development, Goldmann tonometry remains the gold standard to which all other devices are compared. RESUMENAvances recientes en el campo de la tonometría han propiciado el desarrollo de diversos dispositivos con diferentes aplicaciones clíni-cas. Resulta de particular importancia el papel que juegan en el caso de espesores corneales anormales o en presencia de irregularidades en la superficie de la córnea, puesto que, en esos casos, una medida imprecisa de la presión intraocular (PIO) real puede traer como consecuencia una valoración incorrecta del caso. El objetivo de esta revisión es evaluar el grado de precisión de los dispositivos más utilizados hoy en día en casos en los que existen irregularidades en la superficie de la córnea o en el espesor corneal. Para ello, se llevó a cabo una búsqueda de datos entre los artículos publicados. El análisis estuvo basado en una búsqueda bibliográfica realizada dentro de Medline, centrándose principalmente en aquellos artícu-los científicos que habían estudiado el grado de precisión del dispositivo en función del espesor corneal del paciente y de la presencia o no de irregularidades corneales. Se describen en detalle nueve tipos de dispositivos: tonómetro de Goldmann, Tono-Pen, tonómetro de Perkins, Ocular Response Analyzer, tonómetro sin contacto, neumotonómetro, tonómetro de rebote I-Care, tonómetro de contorno dinámico Pascal y tonómetro de fosfeno. Además, se presentan de forma comparada los principios físicos en los que está basado cada tonómetro y las situaciones en las que cada uno resulta de mayor utilidad. Cada uno de los distintos tonómetros disponibles en el mercado presenta ventajas y desventajas respecto...

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Comparison of Dynamic Contour Tonometry and Goldmann Applanation Tonometry in Deep Lamellar and Penetrating Keratoplasties

Ceruti

Morbio

Marraffa

et al. 2008

American Journal of Ophthalmology

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Comparison of IOP measurement using GAT and DCT in patients with penetrating keratoplasties

Cited by 19 publications

References 10 publications

Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Modalities of Tonometry and their Accuracy with Respect to Corneal Thickness and Irregularities

Comparison of Dynamic Contour Tonometry and Goldmann Applanation Tonometry in Deep Lamellar and Penetrating Keratoplasties

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