Intraocular and Episcleral Venous Pressure Increase During Inverted Posture

Friberg, Thomas R.; Sanborn, George E.; Weinreb, Robert N.

doi:10.1016/s0002-9394(14)74275-8

Cited by 188 publications

(145 citation statements)

References 8 publications

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“…Under this circumstance, blood is observed to enter SC. 40 Aqueous cannot flow against the pressure gradient in SC and a highly significant correlation has been found between the episcleral venous pressure and the IOP rise. 40 Two prior studies reported an IOP increase within seconds from the mid-teens to mid-30s following the inversion.…”

Section: Discussionmentioning

confidence: 99%

“…40 Aqueous cannot flow against the pressure gradient in SC and a highly significant correlation has been found between the episcleral venous pressure and the IOP rise. 40 Two prior studies reported an IOP increase within seconds from the mid-teens to mid-30s following the inversion. 39,41 Various clinical diagnostic techniques intentionally induce SC pressure to be higher than IOP.…”

Section: Discussionmentioning

confidence: 99%

“…However, in vivo studies demonstrate that the collapse of the TM prevents fluid from flowing into the AC from SC. 26,34,37,40,[47][48][49] Another confounding variable relates to the ability of the fluid to flow along SC from the cannula end to the other open cut end of the canal in these tissue segments. The cut open end of SC may permit rapid outflow, resulting in a progressive reduction in pressure in locations distal to the cannula end.…”

Section: Discussionmentioning

confidence: 99%

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Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

et al. 2014

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Abstract. The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the trabecular meshwork (TM) with a spatial resolution of ∼5 μm in ex vivo nonhuman primate eyes. We carefully insert a cannula into Schlemm's canal (SC) to control both pressures and flow rates. The experimental results demonstrate the capability of the platform to visualize the unprecedented details of AOS tissue components comparable to that delivered by scanning electron microscopy, as well as to delineate the complex pressure-dependent relationships among the TM, structures within the SC, and collector channel ostia. The described technique provides a new means to characterize the anatomic and pressure-dependent relationships of SC structures, particularly the active motion of collagenous elements at collector channel ostia; such relationships have not previously been amenable to study. Experimental findings suggest that continuing improvements in the OCT imaging of the AOS may provide both insights into the glaucoma enigma and improvements in its management.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

et al. 2014

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“…Our study revealed an average difference of 3 mmHg between SDTC in the sitting and supine positions in individuals with healthy eyes (Table 4). This observation may be due to the possible increase in episcleral venous pressure and the subsequent increase in resistance in the aqueous humor (15,(25)(26)(27)(28) . In the comparison between the pressure peaks measured using SDTC in the supine and sitting positions and the WDT, the results indicated that the highest measurement was obtained using SDTC in the supine position in both glaucomatous and healthy patients (Table 6).…”

Section: Discussionmentioning

confidence: 99%

Intraocular pressure fluctuation in healthy and glaucomatous eyes: a comparative analysis between diurnal curves in supine and sitting positions and the water drinking test

Caiado¹,

Badaró²,

Kasahara³

2014

Arquivos Brasileiros De Oftalmologia

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Approved by the Research Ethics Committee on human beings with the process number 106/06. RESUMO Objetivo: Comparar a flutuação da pressão intraocular (PIO) nas posições sentada e supina, através da curva tensional diária simplificada (CTDS), durante o horário de consultório em pacientes saudáveis e com glaucoma primário de ângulo aberto (GPAA Descritores: Glaucoma de ângulo aberto/fisiopatologia; Pressão intraocular/fi sio logia; Ritmo circadiano ABSTRACTPurpose: To compare intraocular pressure (IOP) using the simplified daily tensional curve (SDTC) between supine and sitting positions in terms of peak levels and amount of fluctuation in both, glaucomatous and healthy subjects. The secondary endpoint was the comparison of these measures with those derived from the water drinking test (WDT). Methods: Thirty patients with primary open-angle glaucoma (POAG) that were undergoing medical therapy and 30 healthy subjects were enrolled in this study. Each patient underwent a diurnal curve between 8 am and 4 pm. After lying down for 5 minutes, the IOP was measured with the Perkins tonometer. Patients were instructed to sit in the upright position for 5 minutes and the tonometry was repeated. At 4:15 pm, the WDT test was performed. Fluctuation was defined as the difference between the highest and the lowest IOP readings (range). The Student's t test was used to assess differences and a P value <0.05 was considered to be statistically significant. Results: The diurnal curve in the supine position demonstrated higher IOP average values (on average 3-4 mmHg higher) compared to the sitting position (p<0.0001) for both groups. IOP peaks were higher in the supine position; however, the IOP range was essentially the same between the three methods. Treated glaucomatous patients had higher IOP levels in all measurements, but the fluctuation for all tests performed appeared to be similar to that of healthy patients. Conclusion:The data suggested that WDT can be used to estimate the diurnal IOP peak and fluctuation observed in the SDTC of the supine position for treated glaucomatous patients. Further studies can compare the possible correlation between the WDT results and those obtained from nocturnal supine measurements.

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“…Foi observado ainda, um defeito de autoregulação do fluxo sanguíneo da artéria central da retina durante a mudança de posição 16 .…”

Section: Gráficounclassified

Influência da postura na pressão intra-ocular e nos defeitos de campo visual no glaucoma primário de ângulo aberto e glaucoma de pressão normal

Meirelles

Mathias²,

Brandão³

et al. 2008

Rev. bras.oftalmol.

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RESUMOObjetivo:Avaliar a variação da pressão intra-ocular (PIO) na mudança de posição em pacientes com glaucoma primário de ângulo aberto (GPAA), glaucoma de pressão normal (GPN) e olhos normais (ON), e correlacionar esta variação à gravidade do defeito de campo visual. Métodos: Foram avaliados 32 olhos de 32 pacientes com GPAA, 30 olhos de 30 pacientes com GPN e 20 olhos de 20 ON. A PIO foi aferida às 6h da manhã na posição supina e 5min após com o paciente sentado. Foi avaliada a correlação entre variação da pressão decorrente da mudança de posição e os defeitos de campo visual. Foram utilizados os testes estatísticos não paramétricos de Kruskal-Wallis, Wilcoxon, Mann-Whitney e o teste de correlação linear de Spearman. Foi considerado significativo valor de p menor que 0,05.Resultados: Foi encontrada diferença significativa entre as pressões intra-oculares na posição supina e assentada nos três grupos (p<0,001). Não houve diferença significativa na variação da PIO com a mudança de posição entre os três grupos (p=0,17). Não houve correlação significativa entre a variação da PIO nas duas posições e o índice MD do campo visual nos grupos GPAA (p=0,81) e GPN (p=0,89). Conclusão:Os resultados sugerem que existe aumento significativo da PIO com a mudança da posição assentada para supina em pacientes com GPAA, GPN e ON, não havendo, porém, diferença significativa desta variação entre os três grupos. Não foi encontrada correlação significativa entre a variação da PIO e a severidade do campo visual.Descritores: Glaucoma de ângulo aberto/diagnóstico; Pressão intra-ocular; Técnicas de diagnóstico oftalmológico; Tonometria ocular/métodos; Estudos de casos e controle 1 Doutor pela Universidade Federal do Rio de Janeiro, Professor Assistente da Universidade Gama Filho, chefe do setor de glaucoma do Hospital Municipal da Piedade -Rio de Janeiro (RJ), Brasil.

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Intraocular and Episcleral Venous Pressure Increase During Inverted Posture

Cited by 188 publications

References 8 publications

Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

Intraocular pressure fluctuation in healthy and glaucomatous eyes: a comparative analysis between diurnal curves in supine and sitting positions and the water drinking test

Influência da postura na pressão intra-ocular e nos defeitos de campo visual no glaucoma primário de ângulo aberto e glaucoma de pressão normal

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