Evaluation of Tonometric Correction Factors

Gunvant, Pinakin; O’Leary, Daniel J.; Baskaran, Mani; Broadway, David C; Watkins, Russell; Vijaya, Lingam

doi:10.1097/01.ijg.0000176940.81799.33

Cited by 68 publications

(62 citation statements)

References 39 publications

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“…These models could be erroneous and lead to an overcorrection of IOP, thus resulting in erroneously low corrected IOP eyes with thicker cornea and erroneously high corrected IOP in eyes with thinner cornea. 25 According to the meta-analysis performed by Doughty that included 600 sets of CCT data, the impact of CCT on applanation tonometry of healthy eyes is unlikely to achieve clinical significance, but for corneas of eyes with chronic disease, pachymetry should be performed if the tonometry reveals IOP readings that are borderline or unusual, and the correction for these eyes should be 2 or 3 mm Hg for a 0.05 mm difference in CCT from 0.535 mm. 26 Looking for the most accurate IOP measurement, GAT has been compared with many other tonometers.…”

Section: Eyementioning

confidence: 99%

Poor agreement between Goldmann and Pascal tonometry in eyes with extreme pachymetry

Millá

Duch

Buchacra

et al. 2008

Eye

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Aim To compare the intraocular pressure (IOP) measurements obtained using the Pascal dynamic contour tonometer (PDCT) with the standard Goldmann applanation tonometry (GAT) and to correlate them with the central corneal thickness (CCT) in a nonglaucomatous population. Methods We prospectively measured IOP using PDCT and GAT in random order in 100 normal eyes. CCT was analysed with an ultrasonic pachymeter in each case. Statistical analysis of baseline and stratified data included intraclass correlation coefficient (ICC), Lin correlation, and Bland-Altman analysis to evaluate the agreement between both techniques. Results GAT was used first in 51 eyes and PDCT in 48 cases. Mean IOP was 14.8 mm Hg with GAT and 20.3 mm Hg with PDCT. Mean pachymetry was 553.23 micrometres (lm) (SD: 4.7 lm). Global agreement of IOP between GAT and PDCT was 0.09 by ICC and 0.170 by Lin correlation. When CCT values ranged between 540 and 545 lm, the agreement between both tonometers was optimal (ICC 0.54 and Lin 0.61). Outside these pachymetry values, agreement between both tonometers diminished dramatically. Conclusion Statistically significant agreement between both devices was reached only at intermediate pachymetry readings in contrast with other studies that show excellent global agreement between GAT and PDCT.

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Section: Eyementioning

confidence: 99%

Poor agreement between Goldmann and Pascal tonometry in eyes with extreme pachymetry

Millá

Duch

Buchacra

et al. 2008

Eye

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“…Fórmulas de correção da TAG foram propostas com base em análises de regressão linear com a ECC (15)(16)(17)(18) . Entretanto, Gunvant et al demonstraram que tais fórmulas podem hipercorrigir a medida da pressão em córneas finas (19) . Por outro lado, córneas com aumento da espessura por edema apresentam uma resistência reduzida e portanto um efeito na TAG similar a córneas com menor espessura (16)(17)(18)(19)(20) .Com isso, recomenda-se muito cuidado no uso de qualquer fórmula baseada em uma suposta relação sempre linear entre a espessura da córnea, sua resistência e seu efeito na TAG (5)(6)(7)(8)(9) .…”

Section: Discussionunclassified

Hipertensão ocular "mascarada" por edema de córnea após cirurgia da catarata

Valbon¹,

Guerra²,

Silva³

et al. 2009

Rev. bras.oftalmol.

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RESUMOCom base em modelos matemáticos e estudos experimentais estima-se que as medidas da PIO sejam linearmente hiperestimadas em córneas com maior espessura e menor ceratometria por meio de tonometria de aplanação de Goldmann (TAG). Entretanto, tal influência se dá de uma maneira mais complexa que a prevista por estes parâmetros geométricos, sendo diretamente relacionada com propriedades biomecânicas. O sistema de não contato ORA (Ocular response analyzer -Reichert) permite estudo das propriedades biomecânicas juntamente com a medida pressórica calibrada para a TAG e a compensada da córnea. Adicionalmente, o estudo tomográfico com reconstrução tridimensional do mapa paquimétrico caracteriza a córnea de forma mais completa que a ceratometria anterior e espessura central. Neste artigo, relatamos um caso de dor ocular, fotofobia e baixa visão, 28 dias após cirurgia de facoemulsificação com implante de lente intraocular sem complicações em paciente feminina de 81 anos. Na primeira visita da paciente, enquanto a TAG era de 16 mmHg, o valor da PIO compensada da córnea (PIOcc), obtido com o ORA, era 25,6 mmHg. A histerese e fator de resistência da córnea eram baixos, 4,1 e 6,1mmHg respectivamente, apesar da paquimetria central ser relativamente mais elevada, de 601 micra. O padrão de distribuição espacial da espessura era atenuado, compatível com edema corneano que era observado também por meio das imagens de Scheimpflug (Pentacam). Com base nestes dados, foi feito diagnóstico de quadro de uveíte hipertensiva, associado à edema corneano, instituindose tratamento tópico com combinação fixa de maleato de timolol e brimonidina associado ao acetato de prednisolona. Três semanas após, a paciente apresentou-se com grande melhora da acuidade visual, resolução do edema corneano, e dos sintomas, normalizando os parâmetros biomecânicos, geométricos da córnea e de PIO.

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“…Although the Goldmann applanation tonometry is still the gold standard among the intraocular pressure measurement methods, this method has been shown to be influenced by many ocular variables such as corneal thickness, refractive errors, corneal edema, and corneal surface defects (8).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of corneal biomechanical properties after uneventful standard coaxial phacoemulsification surgery

Çankaya¹,

Ulaş²,

Doganay³

et al. 2018

J Turgut Ozal Med Cent

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Aim: This study was designed to investigate the alteration of intraocular pressure measurements and biomechanical properties of the cornea in patients who underwent uneventful standard coaxial phacoemulsification cataract surgery through 2.75 mm corneal main incision with intraocular lens implantation. Material and Methods: 15 eyes of 15 patients admitted to our clinic because of the cataract problems in the study. Corneal hysteresis (CH), corneal resistance factor (CRF) measurements, Goldmann correlated (IOPg), and corneal compensated intraocular pressure (IOPcc) values were recorded by ocular response analyzer (ORA) before and 1 day, 1 week and 1 month after surgery. Conclusion:These results revealed that the biomechanical properties of the cornea may change during the first one month period after uneventful standard coaxial phacoemulsification surgery.

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Evaluation of Tonometric Correction Factors

Cited by 68 publications

References 39 publications

Poor agreement between Goldmann and Pascal tonometry in eyes with extreme pachymetry

Poor agreement between Goldmann and Pascal tonometry in eyes with extreme pachymetry

Hipertensão ocular "mascarada" por edema de córnea após cirurgia da catarata

Evaluation of corneal biomechanical properties after uneventful standard coaxial phacoemulsification surgery

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