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Mackenbrock LHB, Baur ID, Łabuz G, Auffarth GU, Khoramnia R. Impact of Phacoemulsification Parameters on Central Retinal Thickness Change Following Cataract Surgery. Diagnostics (Basel) 2023; 13:2856. [PMID: 37685394 PMCID: PMC10487147 DOI: 10.3390/diagnostics13172856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/22/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
Cataract surgery can lead to inflammatory processes in the retina due to its invasive nature, resulting in prolonged recovery times and reduced functional outcomes. The aim of the current study is to explore the impact that phacoemulsification parameters have on macular thickness following surgery. This prospective single-center study enrolled 46 healthy patients (46 eyes) who underwent uneventful cataract surgery. Retinal thickness was assessed using optical coherence tomography (OCT) preoperatively, as well as 1, 4, and 12 weeks after surgery. The macula was divided into a central (CMT), inner (IMT), and outer ring (OMT). Cataract density was automatically determined using an anterior segment OCT and a custom MATLAB script. Corrected distance visual acuity (CDVA), intraocular pressure (IOP) as well as cumulative dissipated energy (CDE), ultrasound time (UT), and fluids used during phacoemulsification were recorded. Retinal thickness and volume increased significantly following cataract surgery, reaching its maximum 4 weeks post-operatively. Statistically significant correlations were found between the CDE and IMT, OMT and retinal volume change (rIMT = 0.356, rOMT = 0.298, rvolume = 0.357 with p < 0.05) as well as between the ultrasound time and IMT, OMT, and retinal volume change (rIMT = 0.369, rOMT = 0.293 and rvolume = 0.409 with p < 0.05). Changes in CMT did not correlate with any surgical metrics. Additionally, no correlation was found to the amount of fluid used, whether CDVA or IOP. However, a link between nuclear cataract density and changes in OMT (r = 0.310, p < 0.05) was established. How ultrasound energy impacts the choroidea, and to what extent retinal metabolism changes after surgery, needs to be explored in future studies.
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Affiliation(s)
| | | | | | | | - Ramin Khoramnia
- Department of Ophthalmology, University Hospital Heidelberg, 69120 Heidelberg, Germany
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2
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Linsenmeier RA, Dmitriev AV, Dmitriev AA. Oxygen profiles and oxygen consumption in the isolated mouse retina. Exp Eye Res 2023; 233:109554. [PMID: 37437835 PMCID: PMC10528762 DOI: 10.1016/j.exer.2023.109554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/14/2023] [Accepted: 06/23/2023] [Indexed: 07/14/2023]
Abstract
The retina has a large demand for oxygen, but there is only limited information on differences between oxygen utilization (QO2) in the inner and outer retina, and limited data on mouse, which has become a prevalent animal model. This study utilized the isolated mouse retina, which allowed more detailed spatial analysis of QO2 than other methods. Oxygen sensitive microelectrodes were used to obtain profiles of oxygen tension across the isolated mouse retina, and mathematical models of retinal oxygen diffusion with four and five layers were fitted to the data to obtain values for QO2 of the outer retina (QOR) and inner retina (QIR). The boundaries between layers were free parameters in these models. The five-layer model resulted in lower error between the model and data, and agreed better with known anatomy. The three layers for the outer retina occupied half of the retina, as in prior work on rat, cat, and monkey, and the inner half of the retina could be divided into two layers, in which the one closer to the vitreous (layer 5) had much lower QO2 than the more distal inner retina (layer 4). QIR in darkness was 3.9 ml O2-100 g-1-min-1, similar to the value for intact cat retina, and did not change during light. QOR in darkness was 2.4 ml O2-100 g-1-min-1, lower than previous values in cat and rat, possibly because of damage to photoreceptors during isolation. There was a tendency for QOR to be lower in light, but it was not significant in this preparation.
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Affiliation(s)
- Robert A Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA; Department of Neurobiology, Northwestern University, Evanston, Illinois, USA; Department of Ophthalmology, Northwestern University, Chicago, Illinois, USA.
| | - Andrey V Dmitriev
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA.
| | - Alexander A Dmitriev
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA.
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Mackenbrock LHB, Weindler JN, Labuz G, Baur ID, Auffarth GU, Khoramnia R. Change in Subfoveal Choroidal Thickness following Cataract Surgery Imaged with Enhanced Depth Imaging Optical Coherence Tomography. Klin Monbl Augenheilkd 2023; 240:989-996. [PMID: 37567233 DOI: 10.1055/a-2120-7415] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
BACKGROUND Due to its invasive nature, cataract surgery can lead to inflammatory processes in the posterior segment, which can result in prolonged recovery times, reduced functional outcomes, and late-onset complications. The aim of the current study was to identify wherever phacoemulsification parameters play a role in choroidal thickness change following cataract surgery. METHODS This prospective single-center study enrolled 31 patients (31 eyes) scheduled to undergo routine cataract surgery. Patients with previous ocular surgeries, pathologies or general disorders affecting vision were excluded. Patients were examined preoperatively, as well as 1, 4, and 12 weeks after surgery. Corrected distance visual acuity (CDVA), intraocular pressure (IOP) as well as cumulative dissipated energy (CDE), ultrasound time (UT), and fluids used during surgery were recorded. Subfoveal choroidal thickness was measured manually by two masked independent experts using enhanced depth imaging (EDI) optical coherence tomography (OCT). Furthermore, cataract density was automatically calculated using a custom MATLAB script and an anterior segment OCT. RESULTS Subfoveal choroidal thickness increased significantly (p < 0.001, Student's paired sample t-test) and continuously during the 12-week-long follow-up period. Both the nuclear lens density and the improvement in CDVA correlated significantly with this increase (r = 0.413, p = 0.021 and r = 0.421, p = 0.018, respectively). Neither the CDE (r = 0.334, p = 0.071), the UT (r = 0.102, p = 0.629), the amount of fluid used (r = 0.237, p = 0.27) nor the decrease in IOP (r = - 0.197, p = 0.288) showed any significant correlation with the choroidal swelling. CONCLUSION Cataract surgery leads to an increase in subfoveal choroidal thickness. While no statistically significant correlation to the phacoemulsification parameters could be established, this might be because of a selection bias due to the technological constraints of the OCT. Nevertheless, the choroid might play a central role in early- and late-onset complications.
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Affiliation(s)
- Lars H B Mackenbrock
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Jan N Weindler
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Grzegorz Labuz
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Isabella D Baur
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Gerd U Auffarth
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Ramin Khoramnia
- Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
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Blair NP, Matei N, Leahy S, Rahimi M, Shahidi M. The accumulated oxygen deficit as an indicator of the ischemic retinal insult. Exp Eye Res 2023; 230:109439. [PMID: 36931487 PMCID: PMC10133208 DOI: 10.1016/j.exer.2023.109439] [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: 09/26/2022] [Revised: 02/24/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
We here attempt to improve quantification of the ischemic retinal insult, that is, what is imposed on the retinal tissue by ischemia, especially in experimental models of ischemia. The ischemic retinal insult initiates the ischemic retinal injury (or outcome). Accordingly, it is reasonable to assume that the better the quantification of the insult, the better the correlation with, and thereby estimation of, the injury. The insult seldom has been quantified in terms of the relevant physiological factors, especially in connection with the rate of oxygen delivery (DO2). We here propose the accumulated oxygen deficit (AO2D) as an indicator of the ischemic retinal insult. We hypothesized that AO2D is correlated with the rate of oxygen metabolism measured 1 h after reperfusion following an episode of ischemia (MO2_1_Hr). Previously, we showed that MO2_1_Hr is related to the electroretinogram amplitude and the retinal thickness when they are measured seven days after reperfusion. We studied 27 rats, as well as 26 rats from our published data on retinal ischemia in which we had measurements of DO2 and duration of ischemia (T) of various levels and durations. We also measured DO2 in 29 rats treated with sham surgery. Ischemia was induced by either ipsilateral or bilateral common carotid artery occlusion or by ophthalmic artery occlusion, which gave a wide range of DO2. DO2 and MO2_1_Hr were evaluated based on three types of images: 1) red-free images to measure vessel diameters, 2) fluorescence images to estimate blood velocities by the displacement of intravascular fluorescent microspheres over time, and 3) phosphorescence images to quantify vascular oxygen tension from the phosphorescence lifetime of an intravascular oxygen sensitive phosphor. Loss of oxygen delivery (DO2L) was calculated as the difference between DO2 under normal/sham condition and DO2 during ischemia. AO2D, a volume of oxygen, was calculated as the product DO2L and T. Including all data, the linear relationship between AO2D and MO2_1_Hr was significant (R2 = 0.261, P = 0.0003). Limiting data to that in which T or DO2L was maximal also yielded significant relationships, and revealed that DO2L at a long duration of ischemia contributed disproportionately more than T to MO2_1_Hr. We discuss the potential of AO2D for quantifying the ischemic retinal insult, predicting the ischemic retinal injury and evaluating the likelihood of infarction.
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Affiliation(s)
- Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 West Taylor Street, Chicago, IL 60612, USA.
| | - Nathanael Matei
- Department of Ophthalmology, University of Southern California, 1450 San Pablo St, Suite 4700, Los Angeles, CA 9003, USA.
| | - Sophie Leahy
- Department of Ophthalmology, University of Southern California, 1450 San Pablo St, Suite 4700, Los Angeles, CA 9003, USA.
| | - Mansour Rahimi
- Department of Ophthalmology, University of Southern California, 1450 San Pablo St, Suite 4700, Los Angeles, CA 9003, USA.
| | - Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, 1450 San Pablo St, Suite 4700, Los Angeles, CA 9003, USA.
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Messerschmidt V, Ren W, Tsipursky M, Irudayaraj J. Characterization of Oxygen Nanobubbles and In Vitro Evaluation of Retinal Cells in Hypoxia. Transl Vis Sci Technol 2023; 12:16. [PMID: 36763051 PMCID: PMC9927786 DOI: 10.1167/tvst.12.2.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Purpose Vein or artery occlusion causes a hypoxic environment by preventing oxygen delivery and diffusion to tissues. Diseases such as retinal vein occlusion, central retinal artery occlusion, or diabetic retinopathy create a stroke-type condition that leads to functional blindness in the effected eye. We aim to develop an oxygen delivery system consisting of oxygen nanobubbles (ONBs) that can mitigate retinal ischemia during a severe hypoxic event such as central retinal artery occlusion. Methods ONBs were synthesized to encapsulate oxygen saturated molecular medical grade water. Stability, oxygen release, biocompatibility, reactive oxygen species, superoxide, MTT, and terminal uridine nick-end labeling assays were performed. Cell viability was evaluated, and safety experiments were conducted in rabbits. Results The ONBs were approximately 220 nm in diameter, with a zeta potential of -58.8 mV. Oxygen release studies indicated that 74.06 µg of O2 is released from the ONBs after 12 hours at 37°C. Cell studies indicated that ONBs are safe and cells are viable. There was no significant increase in reactive oxygen species, superoxide, or double-stranded DNA damage after ONB treatment. ONBs preserve mitochondrial function and viability. Histological sections from rabbit eyes indicated that ONBs were not toxic. Conclusions The ONBs proposed have excellent oxygen holding and release properties to mitigate ischemic conditions in the retina. They are sterile, stable, and nontoxic. Translation Relevance ONB technology was evaluated for its physical properties, oxygen release, sterility, stability, and safety. Our results indicate that ONBs could be a viable treatment approach to mitigate hypoxia during ischemic conditions in the eye upon timely administration.
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Affiliation(s)
- Victoria Messerschmidt
- Biomedical Research Centre (BRC), Mills Breast Cancer Institute, Carle Foundation Hospital, Urbana, IL, USA
| | - Wen Ren
- Biomedical Research Centre (BRC), Mills Breast Cancer Institute, Carle Foundation Hospital, Urbana, IL, USA,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Michael Tsipursky
- Vitreo-Retinal Surgery, Ophthalmology Department, Carle Foundation Hospital, Champaign, IL, USA,Carle-Illinois College of Medicine, Champaign, IL, USA
| | - Joseph Irudayaraj
- Biomedical Research Centre (BRC), Mills Breast Cancer Institute, Carle Foundation Hospital, Urbana, IL, USA,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Carle-Illinois College of Medicine, Champaign, IL, USA,Beckman Institute; Holonyak Micro and Nanotechnology Laboratory; Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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6
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Rahimi M, Leahy S, Matei N, Burford J, Blair NP, Shahidi M. Impairments of retinal hemodynamics and oxygen metrics in ocular hypertension-induced ischemia-reperfusion. Exp Eye Res 2022; 225:109278. [PMID: 36252653 PMCID: PMC10985794 DOI: 10.1016/j.exer.2022.109278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/23/2022] [Accepted: 10/10/2022] [Indexed: 12/29/2022]
Abstract
Ischemia-reperfusion (I/R) is an established model for retinal neurodegeneration. However, there is limited knowledge of retinal physiological metrics and their relationships to retinal function and morphology in the I/R model. The purpose of the study was to test the hypotheses that retinal hemodynamic and oxygen metrics are impaired and associated with visual dysfunction, retinal thinning, and retinal ganglion cell (RGC) loss due to I/R injury. Intraocular pressure (IOP) was increased in one eye of 10 rats for 90 min followed by reperfusion. Fellow eyes served as controls. After one week of reperfusion, multimodal imaging was performed to quantify total retinal blood flow (TRBF) and retinal vascular oxygen contents. Retinal oxygen delivery (DO2) and metabolism (MO2) were calculated. Pattern-evoked electroretinography (PERG) and optical coherence tomography were performed to measure RGC function and retinal thicknesses, respectively. RGCs were counted from retina whole mounts. After one week of reperfusion, TRBF was lower in study eyes than in control eyes (p < 0.0003). Similarly, DO2 and MO2 were reduced in study eyes compared to control eyes (p < 0.003). PERG amplitude, TRT, IRT, ORT, and RGCs were also lower in study eyes (p ≤ 0.01). DO2 and MO2 were correlated with PERG amplitude, TRT, IRT, and ORT (r ≥ 0.6, p ≤ 0.005). The findings improve knowledge of physiological metrics affected by I/R injury and have the potential for identifying biomarkers of injury and outcomes for evaluating experimental treatments.
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Affiliation(s)
- Mansour Rahimi
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Sophie Leahy
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Nathanael Matei
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - James Burford
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Mahnaz Shahidi
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA, 90033, USA.
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Kalloniatis M, Wang H, Katalinic P, Ly A, Apel W, Nivison-Smith L, Kalloniatis KF. Ocular ischaemia: signs, symptoms, and clinical considerations for primary eye care practitioners. Clin Exp Optom 2022; 105:117-134. [PMID: 34982952 DOI: 10.1080/08164622.2021.1999771] [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: 10/19/2022] Open
Abstract
Ischaemic stroke is a major disease burden as well as a leading cause of death. Early signs of ischaemic stroke can manifest in the eye, placing primary eyecare practitioners in an important position to identify patients at risk of ischaemic stroke and initiate suitable referral pathways. The vascular supply to the brain is reviewed with reference to vision including the various retinal signs and ocular symptoms associated with transient ischaemic attacks and ischaemic stroke. Using a range of clinical cases, the diverse clinical presentations of retinal embolic events, as well as other forms of vascular occlusion, are highlighted and the underlying pathophysiology is discussed. A succinct scheme for the assessment and management of ischaemic events for primary eye care practitioners is provided.
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Affiliation(s)
- Michael Kalloniatis
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
| | - Henrietta Wang
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
| | - Paula Katalinic
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
| | - Angelica Ly
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
| | - Warren Apel
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,The Eye Health Centre, Aspley, Australia
| | - Lisa Nivison-Smith
- Centre for Eye Health, the University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
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8
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Matei N, Leahy S, Blair NP, Shahidi M. Assessment of retinal oxygen metabolism, visual function, thickness and degeneration markers after variable ischemia/reperfusion in rats. Exp Eye Res 2021; 213:108838. [PMID: 34774489 DOI: 10.1016/j.exer.2021.108838] [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: 09/10/2021] [Revised: 10/25/2021] [Accepted: 11/08/2021] [Indexed: 12/01/2022]
Abstract
After total retinal ischemia induced experimentally by ophthalmic vessel occlusion followed by reperfusion, studies have reported alterations in retinal oxygen metabolism (MO2), delivery (DO2), and extraction fraction (OEF), as well as visual dysfunction and cell loss. In the current study, under variable durations of ischemia/reperfusion, changes in these oxygen metrics, visual function, retinal thickness, and degeneration markers (gliosis and apoptosis) were assessed and related. Additionally, the prognostic value of MO2 for predicting visual function and retinal thickness outcomes was reported. Sixty-one rats were divided into 5 groups of ischemia duration (0 [sham], 60, 90, 120, or 180 min) and 2 reperfusion durations (1 h, 7 days). Phosphorescence lifetime and blood flow imaging, electroretinography, and optical coherence tomography were performed. MO2 reduction was related to visual dysfunction, retinal thinning, increased gliosis and apoptosis after 7-days reperfusion. Impairment in MO2 after 1-h reperfusion predicted visual function and retinal thickness outcomes after 7-days reperfusion. Since MO2 can be measured in humans, findings from analogous studies may find value in the clinical setting.
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Affiliation(s)
- Nathanael Matei
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, United States
| | - Sophie Leahy
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, United States
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, United States.
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Sharifizad M, Schmidl D, Werkmeister RM, Zeisler H, Told R, Binder J, Küssel L, Garhöfer G, Schmetterer L. Retinal vessel diameters, flicker-induced retinal vasodilation and retinal oxygen saturation in high- and low-risk pregnancy. Acta Ophthalmol 2021; 99:628-636. [PMID: 33326186 PMCID: PMC8519143 DOI: 10.1111/aos.14696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 11/10/2020] [Indexed: 01/12/2023]
Abstract
Purpose To compare retinal vascular parameters between high‐risk and low‐risk pregnant women over time during pregnancy. Methods In a longitudinal study, we included pregnant women with normal blood pressure and normal body mass index (BMI, group 1), pregnant women with systemic hypertension and/or overweight (group 2) and age‐matched nonpregnant healthy women (group 3). Using the dynamic vessel analyser (DVA) we investigated flicker‐induced vasodilation in retinal arteries (FLA) and veins (FLV), central retinal arterial and vein equivalent (CRAE, CRVE), arterio‐venous ratio (AVR) and retinal arterial and venous oxygen saturation (SartO2, SveinO2). Study visits were scheduled 2nd trimester (TP 2), 3rd trimester (TP 3) and postpartum (PP). Results Data from 29 women in group 1, 25 women in group 2 and 33 women in group 3 were included for analysis. FLA, FLV, CRAE, CRVE, AVR and SveinO2 were altered in group 2 (p‐values between < 0.001 and 0.009). At TP 3 the differences between groups were most pronounced. In contrast, there were only minor differences between group 1 and 3. Changes in retinal parameters were independently associated with systemic blood pressure and BMI. Conclusions The present analysis indicates that flicker‐induced retinal vasodilation, retinal vessel diameters and retinal oxygen saturation are altered in high‐risk pregnant women. Hence, these parameters are candidate biomarkers for pregnancy complications, a hypothesis that deserves further study.
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Affiliation(s)
- Mozhgan Sharifizad
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Harald Zeisler
- Department of Obstetrics and Gynecology Medical University of Vienna Vienna Austria
| | - Reinhard Told
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Department of Ophthalmology Medical University of Vienna Vienna Austria
| | - Julia Binder
- Department of Obstetrics and Gynecology Medical University of Vienna Vienna Austria
| | - Lorenz Küssel
- Department of Obstetrics and Gynecology Medical University of Vienna Vienna Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
- Singapore Eye Research Institute Singapore Singapore
- School of Chemical and Biomedical Engineering Nanyang Technological University Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
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10
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Retinal Oxygen Delivery, Metabolism, and Extraction Fraction during Long-Term Bilateral Common Carotid Artery Occlusion in Rats. Sci Rep 2020; 10:10371. [PMID: 32587289 PMCID: PMC7316776 DOI: 10.1038/s41598-020-67255-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 05/27/2020] [Indexed: 12/04/2022] Open
Abstract
Retinal functional, biochemical, and anatomical changes have been previously reported in long-term experimental permanent bilateral common carotid artery occlusion (BCCAO). The purpose of the current study was to investigate progressive reductions in retinal oxygen metabolism (MO2) due to inadequate compensation by oxygen delivery (DO2) and extraction fraction (OEF) after BCCAO. Twenty-nine rats were subjected to BCCAO and were imaged after 3 hours, 3 days, 7 days, or 14 days. Six rats underwent a sham procedure. Phosphorescence lifetime and blood flow imaging were performed in both eyes to measure retinal oxygen contents and total retinal blood flow, respectively. DO2, MO2, and OEF were calculated from these measurements. Compared to the sham group, DO2 and MO2 were reduced after all BCCAO durations. OEF was increased after 3 hours and 3 days of BCCAO, but was not different from the sham group after 7 and 14 days. Between 3 and 7 days of BCCAO, DO2 increased, OEF decreased, and there was no significant difference in MO2. These findings may be useful to understand the pathophysiology of retinal ischemia.
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11
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Blair NP, Leahy S, Nathanael Matei, Shahidi M. Control of retinal blood flow levels by selected combinations of cervical arterial ligations in rat. Exp Eye Res 2020; 197:108088. [PMID: 32502531 DOI: 10.1016/j.exer.2020.108088] [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] [Received: 04/20/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 10/24/2022]
Abstract
The effect of various combinations of cervical arterial ligations (Combinations) on retinal blood flow (RBF) levels is not known in rats. We hypothesized: 1) No artery exists between the Circle of Willis and the eye, 2) Selective Combinations enable varying RBF levels between normal and zero, 3) In certain Combinations, the capillary bed of the head participates in supplying the eye. Twenty-six Combinations were studied in one eye of 20 Long-Evans rats under general anesthesia. RBF was quantitatively evaluated with our published imaging methods based on direct measurements of venous diameter and blood velocity from the displacement of fluorescent microspheres over time. For each Combination, one or more RBF values (runs) were measured. Data were obtained from 59 runs (2.9 ± 2.7 runs/rat). Levels of RBF ranged from normal to zero. An artery between the Circle of Willis and the eye was excluded. With some Combinations, flow traversed the capillary bed. Combinations were consolidated into five Groups based on the blood flow paths remaining after the ligations. A mixed linear model accounting for multiple measurements in the same eye demonstrated an effect of Group on RBF (P < 0.0005). By major source of ocular blood supply, the trend of RBF levels was: ipsilateral carotid artery > contralateral carotid artery > ipsilateral distal internal carotid artery retrograde from Circle of Willis. The findings advanced knowledge of the sources of blood supply to the rat eye and demonstrated a method of selective cervical arterial ligations for varying RBF levels with potential to impact future retinal ischemia research.
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Affiliation(s)
- Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, United States.
| | - Sophie Leahy
- Department of Ophthalmology, University of Southern California, United States.
| | - Nathanael Matei
- Department of Ophthalmology, University of Southern California, United States.
| | - Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, United States.
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12
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Matei N, Leahy S, Auvazian S, Thomas B, Blair NP, Shahidi M. Relation of Retinal Oxygen Measures to Electrophysiology and Survival Indicators after Permanent, Incomplete Ischemia in Rats. Transl Stroke Res 2020; 11:1273-1286. [PMID: 32207038 DOI: 10.1007/s12975-020-00799-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 12/28/2022]
Abstract
Studies in experimental ischemia models by permanent bilateral common carotid artery occlusion (BCCAO) have reported reduced retinal electrophysiological function, coupled with inner retinal degeneration and gliosis. In the current study, we tested the hypothesis that long-term (up to 14 days) BCCAO impairs oxygen delivery (DO2), which affects oxygen metabolism (MO2) and extraction fraction (OEF), electrophysiological function, morphology, and biochemical pathways. Twenty-one rats underwent BCCAO (N = 12) or sham surgery (N = 9) and were evaluated in separate groups after 3, 7, or 14 days. Electroretinography (ERG), optical coherence tomography, blood flow and vascular oxygen tension imaging, and morphological and biochemical evaluations were performed in both eyes. Reduced ERG b-wave amplitudes and delayed implicit times were reported at 3, 7, and 14 days following BCCAO. Total retinal blood flow, MO2, and DO2 were reduced in all BCCAO groups. OEF was increased in both 3- and 7-day groups, while no significant difference was observed in OEF at 14 days compared to the sham group. At 14 days following BCCAO, total and inner retinal layer thickness was reduced, while the outer nuclear layer thickness and gliosis were increased. There was an increase in nuclei containing fragmented DNA at 3 days following BCCAO. The compensatory elevation in OEF following BCCAO did not meet the tissue demand, resulting in the subsequent reduction of MO2. The associations between retinal MO2, DO2, and retinal function were shown to be significant in the sequelae of persistent ischemia. In sum, measurements of DO2, MO2, and OEF may become useful for characterizing salvageable tissue in vision-threatening pathologies.
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Affiliation(s)
- Nathanael Matei
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA
| | - Sophie Leahy
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA
| | - Selin Auvazian
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA
| | - Biju Thomas
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA.
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Karamian P, Burford J, Farzad S, Blair NP, Shahidi M. Alterations in Retinal Oxygen Delivery, Metabolism, and Extraction Fraction During Bilateral Common Carotid Artery Occlusion in Rats. Invest Ophthalmol Vis Sci 2019; 60:3247-3253. [PMID: 31343655 PMCID: PMC6660186 DOI: 10.1167/iovs.19-27227] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose The purpose of the current study was to investigate alterations in retinal oxygen delivery, metabolism, and extraction fraction and elucidate their relationships in an experimental model of retinal ischemia. Methods We subjected 14 rats to permanent bilateral common carotid artery occlusion using clamp or suture ligation, or they underwent sham procedure. Within 30 minutes of the procedure, phosphorescence lifetime imaging was performed to measure retinal vascular oxygen tension and derive arterial and venous oxygen contents, and arteriovenous oxygen content difference. Fluorescent microsphere and red-free retinal imaging were performed to measure total retinal blood flow. Retinal oxygen delivery rate (DO2), oxygen metabolism rate (MO2), and oxygen extraction fraction (OEF) were calculated. Results DO2 and MO2 were lower in ligation and clamp groups compared to the sham group, and also lower in the ligation group compared to the clamp group (P ≤ 0.05). OEF was higher in the ligation group compared to clamp and sham groups (P ≤ 0.03). The relationships of MO2 and OEF with DO2 were mathematically modeled by exponential functions. With moderate DO2 reductions, OEF increased while MO2 minimally decreased. Under severe DO2 reductions, OEF reached a maximum value and subsequently MO2 decreased with DO2. Conclusions The findings improve knowledge of mechanisms that can maintain MO2 and may clarify the pathophysiology of retinal ischemic injury.
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Affiliation(s)
- Preny Karamian
- Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
| | - James Burford
- Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
| | - Shayan Farzad
- Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
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