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段 雪, 韦 锦, 梁 安, 纪 雪. [Small tidal volume hyperventilation relieves intraocular and intracranial pressure elevation in prone spinal surgery: a randomized controlled trial]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2024; 44:660-665. [PMID: 38708498 PMCID: PMC11073951 DOI: 10.12122/j.issn.1673-4254.2024.04.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Indexed: 05/07/2024]
Abstract
OBJECTIVE To investigate the effects of different ventilation strategies on intraocular pressure (IOP) and intracranial pressure in patients undergoing spinal surgery in the prone position under general anesthesia. METHODS Seventy-two patients undergoing prone spinal surgery under general anesthesia between November, 2022 and June, 2023 were equally randomized into two groups to receive routine ventilation (with Vt of 8mL/kg, Fr of 12-15/min, and etCO2 maintained at 35-40 mmHg) or small tidal volume hyperventilation (Vt of 6 mL/kg, Fr of18-20/min, and etCO2 maintained at 30-35 mmHg) during the surgery. IOP of both eyes (measured with a handheld tonometer), optic nerve sheath diameter (ONSD; measured at 3 mm behind the eyeball with bedside real-time ultrasound), circulatory and respiratory parameters of the patients were recorded before anesthesia (T0), immediately after anesthesia induction (T1), immediately after prone positioning (T2), at 2 h during operation (T3), immediately after supine positioning after surgery (T4) and 30 min after the operation (T5). RESULTS Compared with those at T1, IOP and ONSD in both groups increased significantly at T3 and T4(P < 0.05). IOP was significantly lower in hyperventilation group than in routine ventilation group at T3 and T4(P < 0.05), and ONSD was significantly lower in hyperventilation group at T4(P < 0.05). IOP was positively correlated with the length of operative time (r=0.779, P < 0.001) and inversely with intraoperative etCO2 at T3(r=-0.248, P < 0.001) and T4(r=-0.251, P < 0.001).ONSD was correlated only with operation time (r=0.561, P < 0.05) and not with IOP (r=0.178, P>0.05 at T3; r=0.165, P>0.05 at T4). CONCLUSION Small tidal volume hyperventilation can relieve the increase of IOP and ONSD during prone spinal surgery under general anesthesia.
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Affiliation(s)
- 雪飞 段
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 锦锋 韦
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 安怡 梁
- 南方医科大学附属广东省人民医院眼科, 广东 广州 510080Department of Ophthalmology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 雪霞 纪
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
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Nicou CM, Passaglia CL. Characterization of intraocular pressure variability in conscious rats. Exp Eye Res 2024; 239:109757. [PMID: 38123009 PMCID: PMC10922224 DOI: 10.1016/j.exer.2023.109757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/10/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
Elevation of mean intraocular pressure (IOP) has long been recognized as a leading risk factor for glaucoma. Less is known about the possible contribution of moment-to-moment variations in IOP to disease development and progression due to limitations of tonometry, the prevailing method of IOP measurement. Tonometry provides good estimates of mean IOP but not IOP variance. The aim of this study was to quantitatively characterize IOP variability via round-the-clock IOP telemetry in conscious unrestrained rats. The anterior chamber of one eye was implanted with a microcannula connected to a wireless backpack telemetry system, and IOP data were collected every 4 s for one week. The cannula was then repositioned under the conjunctiva, and control data were collected for an additional week. IOP statistics were computed in 30-min intervals over a 24-h period and averaged across days. All animals exhibited a diurnal variation in mean IOP, while deviations about the mean were independent of time of day. Correlation analysis of the deviations revealed transient and sustained components, which were respectively extracted from IOP records using an event detection algorithm. The amplitude and interval distributions of transient and sustained events were characterized, and their energy content was estimated based on outflow tissue resistance of rat eyes. Transient IOP events occurred ∼231 times per day and were typically ≤5 mmHg in amplitude and 2-8 min in duration, while sustained IOP events occurred ∼16 times per day and were typically ≤5 mmHg in amplitude and 20-60 min in duration. Both persisted but were greatly reduced in control recordings, implying minor contamination of IOP data by motion-induced telemetry noise. Sustained events were also often synchronous across implanted animals, indicating that they were driven by autonomic startle and stress responses or other physiological processes activated by sensory signals in the animal housing environment. Not surprisingly, the total daily fluidic energy applied to resistive outflow pathways was determined primarily by basal IOP level. Nevertheless, transient and sustained fluctuations collectively contributed 6% and diurnal fluctuations contributed 9% to daily IOP energy. It is therefore important to consider the cumulative impact of biomechanical stress that IOP fluctuations apply over time to ocular tissues.
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Affiliation(s)
- Christina M Nicou
- Medical Engineering Department, University of South Florida, Tampa, FL, 33620, USA
| | - Christopher L Passaglia
- Medical Engineering Department, University of South Florida, Tampa, FL, 33620, USA; Ophthalmology Department, University of South Florida, Tampa, FL, 33620, USA.
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Cheng Y, Lin D, Wu S, Liu Q, Yan X, Ren T, Zhang J, Wang N. Cerebrospinal Fluid Pressure Reduction Induces Glia-Mediated Retinal Inflammation and Leads to Retinal Ganglion Cell Injury in Rats. Mol Neurobiol 2023; 60:5770-5788. [PMID: 37347366 DOI: 10.1007/s12035-023-03430-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 06/05/2023] [Indexed: 06/23/2023]
Abstract
Low intracranial pressure (LICP)-induced translaminar cribrosa pressure difference (TLCPD) elevation has been proven as a risk factor in glaucomatous neurodegeneration, whereas the underlying retinal immune features of LICP-induced retinal ganglion cells (RGC) injury remain elusive. Here, we identified the retinal immune characteristics of LICP rats, and minocycline (Mino) treatment was utilized to analyze its inhibitory role in glia-mediated retinal inflammation of LICP rats. The results showed that retrograde axonal transport was decreased in LICP rats without significant RGC loss, indicating the RGC injury was at an early stage before the morphological loss. The activation of retinal microglia and astrocytes with morphologic and M1 or A1-marker alternations was detected in TLCPD elevation rats, the activation level is more dramatic in HIOP rats than in the LICP rats (P<0.05). Besides, we detected reduced retinal tight junction protein expressions, accompanied by specific imbalance patterns of T lymphocytes in the retina of both LICP and HIOP rats (P<0.05). Further Mino treatment showed an effective inhibitory role in glia-driven inflammatory responses in LICP rats, including improving retrograde axonal transport, inhibiting retinal glial activation and proinflammatory subtype polarization, and alleviating the blood-retina barrier compromise. This study identified the glia-mediated retinal inflammation features triggered by LICP stimulus, and Mino application exhibited an effective role in the inhibition of retinal glia-mediated inflammation in LICP-induced TLCPD elevation rats.
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Affiliation(s)
- Ying Cheng
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China
| | - Danting Lin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Qian Liu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Xuejing Yan
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Tianmin Ren
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Jingxue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China.
- Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China.
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China.
- Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, 100069, China.
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
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Mohamed Y, Passaglia CL. A portable feedback-controlled pump for monitoring eye outflow facility in conscious rats. PLoS One 2023; 18:e0280332. [PMID: 36630474 PMCID: PMC9833506 DOI: 10.1371/journal.pone.0280332] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/27/2022] [Indexed: 01/12/2023] Open
Abstract
Intraocular pressure (IOP) is heavily influenced by the resistance of trabecular outflow pathways through which most of the aqueous humor produced by the eye continuously drains. The standard method of quantifying outflow resistance and other aspects of ocular fluid dynamics is eye cannulation, which allows for direct measurement and manipulation of IOP and flow in animal models. Since the method is invasive, indirect techniques that are slower and less accurate must be used for chronological studies. A novel technology is introduced that can autonomously measure outflow facility in conscious rats multiple times a day. A smart portable micropump infuses fluid into the eye through a permanently-implanted cannula and dynamically adjusts flow rate using a unique proportional feedback algorithm that sets IOP to a target level, even though IOP fluctuates erratically in awake free-moving animals. Pressure-flow data collected by the system from anesthetized rats were validated against intraocular recordings with commercial pressure and flow sensors. System and sensor estimates of outflow facility were indistinguishable, averaging 23 ± 3 nl·min-1·mmHg-1 across animals (n = 11). Pressure-flow data were then collected round-the-clock for several days from conscious rats, while outflow facility was measured every few hours. A significant diurnal facility rhythm was observed in every animal (n = 4), with mean daytime level of 22 ± 10 nl·min-1·mmHg-1 and mean nighttime level of 15 ± 7 nl·min-1·mmHg-1. The rhythm correlated with diurnal changes in IOP and likely contributed prominently to those changes based on the day-night swing in facility magnitude. Hence, the portable smart pump offers a unique tool for repeated long-term monitoring of outflow facility and other possible parameters of ocular health. It could also be useful in animal glaucoma studies for reversibly inducing acute or chronic ocular hypertension without explicitly damaging trabecular outflow pathways.
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Affiliation(s)
- Youssef Mohamed
- Department of Medical Engineering, University of South Florida, Tampa, FL, United States of America
| | - Christopher L. Passaglia
- Department of Medical Engineering, University of South Florida, Tampa, FL, United States of America
- Department of Ophthalmology, University of South Florida, Tampa, FL, United States of America
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Faiq MA, Sengupta T, Nath M, Velpandian T, Saluja D, Dada R, Dada T, Chan KC. Ocular manifestations of central insulin resistance. Neural Regen Res 2022; 18:1139-1146. [PMID: 36255004 PMCID: PMC9827783 DOI: 10.4103/1673-5374.355765] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Central insulin resistance, the diminished cellular sensitivity to insulin in the brain, has been implicated in diabetes mellitus, Alzheimer's disease and other neurological disorders. However, whether and how central insulin resistance plays a role in the eye remains unclear. Here, we performed intracerebroventricular injection of S961, a potent and specific blocker of insulin receptor in adult Wistar rats to test if central insulin resistance leads to pathological changes in ocular structures. 80 mg of S961 was stereotaxically injected into the lateral ventricle of the experimental group twice at 7 days apart, whereas buffer solution was injected to the sham control group. Blood samples, intraocular pressure, trabecular meshwork morphology, ciliary body markers, retinal and optic nerve integrity, and whole genome expression patterns were then evaluated. While neither blood glucose nor serum insulin level was significantly altered in the experimental or control group, we found that injection of S961 but not buffer solution significantly increased intraocular pressure at 14 and 24 days after first injection, along with reduced porosity and aquaporin 4 expression in the trabecular meshwork, and increased tumor necrosis factor α and aquaporin 4 expression in the ciliary body. In the retina, cell density and insulin receptor expression decreased in the retinal ganglion cell layer upon S961 injection. Fundus photography revealed peripapillary atrophy with vascular dysregulation in the experimental group. These retinal changes were accompanied by upregulation of pro-inflammatory and pro-apoptotic genes, downregulation of anti-inflammatory, anti-apoptotic, and neurotrophic genes, as well as dysregulation of genes involved in insulin signaling. Optic nerve histology indicated microglial activation and changes in the expression of glial fibrillary acidic protein, tumor necrosis factor α, and aquaporin 4. Molecular pathway architecture of the retina revealed the three most significant pathways involved being inflammation/cell stress, insulin signaling, and extracellular matrix regulation relevant to neurodegeneration. There was also a multimodal crosstalk between insulin signaling derangement and inflammation-related genes. Taken together, our results indicate that blocking insulin receptor signaling in the central nervous system can lead to trabecular meshwork and ciliary body dysfunction, intraocular pressure elevation, as well as inflammation, glial activation, and apoptosis in the retina and optic nerve. Given that central insulin resistance may lead to neurodegenerative phenotype in the visual system, targeting insulin signaling may hold promise for vision disorders involving the retina and optic nerve.
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Affiliation(s)
- Muneeb A. Faiq
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,Neuroimaging and Visual Science Laboratory, Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY, USA,Medical Biotechnology Laboratory, Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Trina Sengupta
- Dr. Baldev Singh Sleep Laboratory, Department of Physiology, All India Institute of Medical Sciences, New Delhi, India
| | - Madhu Nath
- Department of Ocular Pharmacology, Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Thirumurthy Velpandian
- Department of Ocular Pharmacology, Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Daman Saluja
- Medical Biotechnology Laboratory, Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Rima Dada
- Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Tanuj Dada
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,Correspondence to: Tanuj Dada, ; Kevin C. Chan, .
| | - Kevin C. Chan
- Neuroimaging and Visual Science Laboratory, Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY, USA,Correspondence to: Tanuj Dada, ; Kevin C. Chan, .
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Karimi A, Razaghi R, Rahmati SM, Girkin CA, Downs JC. Relative Contributions of Intraocular and Cerebrospinal Fluid Pressures to the Biomechanics of the Lamina Cribrosa and Laminar Neural Tissues. Invest Ophthalmol Vis Sci 2022; 63:14. [PMID: 36255364 PMCID: PMC9587471 DOI: 10.1167/iovs.63.11.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 09/27/2022] [Indexed: 12/02/2022] Open
Abstract
Purpose The laminar region of the optic nerve head (ONH), thought to be the site of damage to the retinal ganglion cell axons in glaucoma, is continuously loaded on its anterior and posterior surfaces by dynamic intraocular pressure (IOP) and orbital cerebrospinal fluid pressure (CSFP), respectively. Thus, translaminar pressure (TLP; TLP = IOP-CSFP) has been proposed as a glaucoma risk factor. Methods Three eye-specific finite element models of the posterior human eye were constructed, including full 3D microstructures of the load-bearing lamina cribrosa (LC) with interspersed laminar neural tissues (NTs), and heterogeneous, anisotropic, hyperelastic material formulations for the surrounding peripapillary sclera and adjacent pia. ONH biomechanical responses were simulated using three combinations of IOP and CSFP loadings consistent with posture change from sitting to supine. Results Results show that tensile, compressive, and shear stresses and strains in the ONH were higher in the supine position compared to the sitting position (P < 0.05). In addition, LC beams bear three to five times more TLP-driven stress than interspersed laminar NT, whereas laminar NT exhibit three to five times greater strain than supporting LC (P < 0.05). Compared with CSFP, IOP drove approximately four times greater stress and strain in the LC, NT, and peripapillary sclera, normalized per mm Hg pressure change. In addition, IOP drove approximately three-fold greater scleral canal expansion and anterior-posterior laminar deformation than CSFP per mm Hg (P < 0.05). Conclusions Whereas TLP has been hypothesized to play a prominent role in ONH biomechanics, the IOP and CSFP effects are not equivalent, as IOP-driven stress, strain, and deformation play a more dominant role than CSFP effects.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | | | - Christopher A. Girkin
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
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Zhu Z, Waxman S, Wang B, Wallace J, Schmitt SE, Tyler-Kabara E, Ishikawa H, Schuman JS, Smith MA, Wollstein G, Sigal IA. Interplay between intraocular and intracranial pressure effects on the optic nerve head in vivo. Exp Eye Res 2021; 213:108809. [PMID: 34736887 DOI: 10.1016/j.exer.2021.108809] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 10/19/2021] [Accepted: 10/25/2021] [Indexed: 12/19/2022]
Abstract
Intracranial pressure (ICP) has been proposed to play an important role in the sensitivity to intraocular pressure (IOP) and susceptibility to glaucoma. However, the in vivo effects of simultaneous, controlled, acute variations in ICP and IOP have not been directly measured. We quantified the deformations of the anterior lamina cribrosa (ALC) and scleral canal at Bruch's membrane opening (BMO) under acute elevation of IOP and/or ICP. Four eyes of three adult monkeys were imaged in vivo with OCT under four pressure conditions: IOP and ICP either at baseline or elevated. The BMO and ALC were reconstructed from manual delineations. From these, we determined canal area at the BMO (BMO area), BMO aspect ratio and planarity, and ALC median depth relative to the BMO plane. To better account for the pressure effects on the imaging, we also measured ALC visibility as a percent of the BMO area. Further, ALC depths were analyzed only in regions where the ALC was visible in all pressure conditions. Bootstrap sampling was used to obtain mean estimates and confidence intervals, which were then used to test for significant effects of IOP and ICP, independently and in interaction. Response to pressure manipulation was highly individualized between eyes, with significant changes detected in a majority of the parameters. Significant interactions between ICP and IOP occurred in all measures, except ALC visibility. On average, ICP elevation expanded BMO area by 0.17 mm2 at baseline IOP, and contracted BMO area by 0.02 mm2 at high IOP. ICP elevation decreased ALC depth by 10 μm at baseline IOP, but increased depth by 7 μm at high IOP. ALC visibility decreased as ICP increased, both at baseline (-10%) and high IOP (-17%). IOP elevation expanded BMO area by 0.04 mm2 at baseline ICP, and contracted BMO area by 0.09 mm2 at high ICP. On average, IOP elevation caused the ALC to displace 3.3 μm anteriorly at baseline ICP, and 22 μm posteriorly at high ICP. ALC visibility improved as IOP increased, both at baseline (5%) and high ICP (8%). In summary, changing IOP or ICP significantly deformed both the scleral canal and the lamina of the monkey ONH, regardless of the other pressure level. There were significant interactions between the effects of IOP and those of ICP on LC depth, BMO area, aspect ratio and planarity. On most eyes, elevating both pressures by the same amount did not cancel out the effects. Altogether our results show that ICP affects sensitivity to IOP, and thus that it can potentially also affect susceptibility to glaucoma.
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Affiliation(s)
- Ziyi Zhu
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bo Wang
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jacob Wallace
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Samantha E Schmitt
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Elizabeth Tyler-Kabara
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurosurgery, University of Texas-Austin, Austin, TX, USA
| | - Hiroshi Ishikawa
- Department of Ophthalmology, NYU School of Medicine, New York, NY, USA
| | - Joel S Schuman
- Department of Ophthalmology, NYU School of Medicine, New York, NY, USA
| | - Matthew A Smith
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Gadi Wollstein
- Department of Ophthalmology, NYU School of Medicine, New York, NY, USA
| | - Ian A Sigal
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA.
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Nicou CM, Pillai A, Passaglia CL. Effects of acute stress, general anesthetics, tonometry, and temperature on intraocular pressure in rats. Exp Eye Res 2021; 210:108727. [PMID: 34390732 DOI: 10.1016/j.exer.2021.108727] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/30/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
Intraocular pressure (IOP) is important for eye health as abnormal levels can led to ocular tissue damage. IOP is typically estimated by tonometry, which only provides snapshots of pressure history. Tonometry also requires subject cooperation and corneal contact that may influence IOP readings. The aim of this research was to investigate IOP dynamics of conscious animals in response to stressors, common anesthetics, tonometry, and temperature manipulations. An eye of male Brown-Norway rats was implanted with a fluid-filled cannula connected to a wireless telemetry system that records IOP continuously. Stress effects were examined by restricting animal movements. Anesthetic effects were examined by varying isoflurane concentration or injecting a bolus of ketamine. Tonometry effects were examined using applanation and rebound tonometers. Temperature effects were examined by exposing anesthetized and conscious animals to warm or cool surfaces. Telemetry recordings revealed that IOP fluctuates spontaneously by several mmHg, even in idle and anesthetized animals. Environmental disturbances also caused transient IOP fluctuations that were synchronous in recorded animals and could last over a half hour. Animal immobilization produced a rapid sustained elevation of IOP that was blocked by anesthetics, whereas little-to-no IOP change was detected in isoflurane- or ketamine-anesthetized animals if body temperature (BT) was maintained. IOP and BT decreased precipitously when heat support was not provided and were highly correlated during surface temperature manipulations. Surface temperature had no impact on IOP of conscious animals. IOP increased slightly during applanation tonometry but not rebound tonometry. The results show that IOP is dynamically modulated by internal and external factors that can activate rapidly and last long beyond the initiating event. Wireless telemetry indicates that animal interaction induces startle and stress responses that raise IOP. Anesthesia blocks these responses, which allows for better tonometry estimates of resting IOP provided that BT is controlled.
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Affiliation(s)
- Christina M Nicou
- Medical Engineering Department, University of South Florida, Tampa, FL, 33620, USA
| | - Aditi Pillai
- Medical Engineering Department, University of South Florida, Tampa, FL, 33620, USA
| | - Christopher L Passaglia
- Medical Engineering Department, University of South Florida, Tampa, FL, 33620, USA; Ophthalmology Department, University of South Florida, Tampa, FL, 33620, USA.
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Li J, Wan C. Non-invasive detection of intracranial pressure related to the optic nerve. Quant Imaging Med Surg 2021; 11:2823-2836. [PMID: 34079745 DOI: 10.21037/qims-20-1188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.
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Affiliation(s)
- Jian Li
- Department of Radiology, the First Hospital of China Medical University, Shenyang, China
| | - Chao Wan
- Department of Ophthalmology, the First Hospital of China Medical University, Shenyang, China
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Ghate D, Kedar S, Havens S, Fan S, Thorell W, Nelson C, Gu L, Tong J, Gulati V. The Effects of Acute Intracranial Pressure Changes on the Episcleral Venous Pressure, Retinal Vein Diameter and Intraocular Pressure in a Pig Model. Curr Eye Res 2020; 46:524-531. [PMID: 32806985 DOI: 10.1080/02713683.2020.1805769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE Orbital veins such as the retinal veins and episcleral veins drain into the cavernous sinus, an intracranial venous structure. We studied the effects of acute intracranial pressure (ICP) elevation on episcleral venous pressure, intraocular pressure and retinal vein diameter in an established non-survival pig model. METHODS In six adult female domestic pigs, we increased ICP in 5 mm Hg increments using saline infusion through a lumbar drain. We measured ICP (using parenchymal pressure monitor), intraocular pressure (using pneumatonometer), episcleral venous pressure (using venomanometer), retinal vein diameter (using OCT images) and arterial blood pressure at each stable ICP increment. The average baseline ICP was 5.4 mm Hg (range 1.5-9 mm Hg) and the maximum stable ICP ranged from 18 to 40 mm Hg. Linear mixed models with random intercepts were used to evaluate the effect of acute ICP increase on outcome variables. RESULTS With acute ICP elevation, we found loss of retinal venous pulsation and increased episcleral venous pressure, intraocular pressure and retinal vein pressure in all animals. Specifically, acute ICP increase was significantly associated with episcleral venous pressure (β = 0.31; 95% CI 0.14-0.48, p < .001), intraocular pressure (β = 0.37, 95%CI 0.24-0.50; p < .001) and retinal vein diameter (β = 11.29, 95%CI 1.57-21.00; p = .03) after controlling for the effects of arterial blood pressure. CONCLUSION We believe that the ophthalmic effects of acute ICP elevation are mediated by increased intracranial venous pressure producing upstream pressure changes within the orbital and retinal veins. These results offer exciting possibilities for the development of non-invasive ophthalmic biomarkers to estimate acute ICP elevations following significant neuro-trauma.
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Affiliation(s)
- Deepta Ghate
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | - Sachin Kedar
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA.,Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Shane Havens
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | - Shan Fan
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | - William Thorell
- Department of Neurosurgery, University of Nebraska Medical Center, Omaha, NE, USA
| | - Carl Nelson
- Department of Mechanical Engineering, University of Nebraska, Lincoln, NE, USA
| | - Linxia Gu
- Department of Mechanical Engineering, University of Nebraska, Lincoln, NE, USA.,Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - Junfei Tong
- Department of Mechanical Engineering, University of Nebraska, Lincoln, NE, USA
| | - Vikas Gulati
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA
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Jaki Mekjavic P, Tipton MJ, Mekjavic IB. The eye in extreme environments. Exp Physiol 2020; 106:52-64. [DOI: 10.1113/ep088594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/05/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Polona Jaki Mekjavic
- University Medical Centre Ljubljana Eye Clinic Ljubljana Slovenia
- Faculty of Medicine University of Ljubljana Ljubljana Slovenia
- Department of Automation Biocybernetics and Robotics Jozef Stefan Institute Ljubljana Slovenia
| | - Michael J. Tipton
- School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Igor B Mekjavic
- Department of Automation Biocybernetics and Robotics Jozef Stefan Institute Ljubljana Slovenia
- Department of Biomedical Physiology and Kinesiology Simon Fraser University Burnaby British Columbia Canada
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Jaki Mekjavic P, Amoaku W, Mlinar T, Mekjavic IB. The aetiology of spaceflight-associated neuro-ocular syndrome might be explained by a neural mechanism regulating intraocular pressure. J Physiol 2020; 598:1431-1432. [PMID: 32118293 DOI: 10.1113/jp279699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 02/28/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Polona Jaki Mekjavic
- Faculty of Medicine, University of Ljubljana, Ljubljana, SI-1000, Slovenia.,University Medical Centre Ljubljana Eye Clinic, Ljubljana, SI-1000, Slovenia.,Jozef Stefan Institute, Ljubljana, SI-1000, Slovenia
| | - Winfried Amoaku
- Nottingham Eye Research Centre, Division of Clinical Neurosciences, University of Nottingham, Nottingham, United Kingdom
| | - Tinkara Mlinar
- Jozef Stefan Institute, Ljubljana, SI-1000, Slovenia.,International Postgraduate School Jozef Stefan, Ljubljana, SI-1000, Slovenia
| | - Igor B Mekjavic
- Jozef Stefan Institute, Ljubljana, SI-1000, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
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