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Xuan M, Wang W, Bulloch G, Zhang J, Ha J, Wang Q, Wang J, Lin X, He M. Impact of Acute Ocular Hypertension on Retinal Ganglion Cell Loss in Mice. Transl Vis Sci Technol 2024; 13:17. [PMID: 38506800 PMCID: PMC10959197 DOI: 10.1167/tvst.13.3.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 02/07/2024] [Indexed: 03/21/2024] Open
Abstract
Purpose To assess the correlation between intraocular pressure (IOP) levels and retinal ganglion cell (RGC) loss across different fixed-duration episodes of acute ocular hypertension (AOH). Methods AOH was induced in Thy1-YFP-H transgenic mice by inserting a needle connected to a saline solution container into the anterior chamber. Thirty-one groups were tested, each comprising three to five mice exposed to IOP levels ranging from 50 to 110 mm Hg in 5/10 mm Hg increments for 60/90/120 minutes and a sham control group. The YFP-expressing RGCs were quantified by confocal scanning laser ophthalmoscopy, whereas peripapillary ganglion cell complex thickness was measured using spectral-domain optical coherence tomography. Changes in RGC count and GCCT were determined from values measured 30 days after AOH relative to baseline (before AOH). Results In the 60-minute AOH groups, RGC loss varied even when IOP was increased up to 110 mm Hg (36.8%-68.2%). However, for longer durations (90 and 120 minutes), a narrow range of IOP levels (60-70 mm Hg for 90-minute duration; 55-65 mm Hg for 120-minute duration) produced a significant difference in RGC loss, ranging from <25% to >90%. Additionally, loss of YFP-expressing RGCs was comparable to that of total RGCs in the same retinas. Conclusions Reproducible RGC loss during AOH depends on precise durations and IOP thresholds. In the current study, the optimal choice is an AOH protocol set at 70 mm Hg for a duration of 90 minutes. Translational Relevance This study can assist in determining the optimal duration and intensity of IOP for the effective utilization of AOH models.
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Affiliation(s)
- Meng Xuan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Wei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Gabriella Bulloch
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
- Faculty of Science, Medicine and Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Jian Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Jason Ha
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
| | - Qilin Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Juanjuan Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xingyan Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Mingguang He
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- Research Centre for SHARP Vision (RCSV), The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- Centre for Eye and Vision Research (CEVR), Hong Kong, China
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Agarwal R, Agarwal P, Iezhitsa I. Exploring the current use of animal models in glaucoma drug discovery: where are we in 2023? Expert Opin Drug Discov 2023; 18:1287-1300. [PMID: 37608634 DOI: 10.1080/17460441.2023.2246892] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/08/2023] [Indexed: 08/24/2023]
Abstract
INTRODUCTION Animal models are widely used in glaucoma-related research. Since the elevated intraocular pressure (IOP) is a major risk factor underlying the disease pathogenesis, animal models with high IOP are commonly used. However, models are also used to represent the clinical context of glaucomatous changes developing despite a normal IOP. AREAS COVERED Herein, the authors discuss the various factors that contribute to the quality of studies using animal models based on the evaluation of studies published in 2022. The factors affecting the quality of studies using animal models, such as the animal species, age, and sex, are discussed, along with various methods and outcomes of studies involving different animal models of glaucoma. EXPERT OPINION Translating animal research data to clinical applications remains challenging. Our observations in this review clearly indicate that many studies lack scientific robustness not only in their experiment conduct but also in data analysis, interpretation, and presentation. In this context, ensuring the internal validity of animal studies is the first step in quality assurance. External validity, however, is more challenging, and steps should be taken to satisfy external validity at least to some extent.
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Affiliation(s)
- Renu Agarwal
- School of Medicine, International Medical University, Bukit Jalil, Malaysia
| | - Puneet Agarwal
- School of Medicine, International Medical University, Bukit Jalil, Malaysia
| | - Igor Iezhitsa
- School of Medicine, International Medical University, Bukit Jalil, Malaysia
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Sharif NA. Identifying new drugs and targets to treat rapidly elevated intraocular pressure for angle closure and secondary glaucomas to curb visual impairment and prevent blindness. Exp Eye Res 2023; 232:109444. [PMID: 36958427 DOI: 10.1016/j.exer.2023.109444] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/23/2023] [Accepted: 03/16/2023] [Indexed: 03/25/2023]
Abstract
A multitude of pharmacological compounds have been shown to lower and control intraocular pressure (IOP) in numerous species of animals and human subjects after topical ocular dosing or via other routes of administration. Most researchers have been interested in finding drug candidates that exhibit a relatively long duration of action from a chronic therapeutic use perspective, for example to treat ocular hypertension (OHT), primary open-angle glaucoma and even normotensive glaucoma. However, it is equally important to seek and characterize treatment modalities which offer a rapid onset of action to help provide fast relief from quickly rising IOP that occurs in certain eye diseases. These include acute angle-closure glaucoma, primary angle-closure glaucoma, uveitic and inflammatory glaucoma, medication-induced OHT, and other secondary glaucomas induced by eye injury or infection which can cause partial or complete loss of eyesight. Such fast-acting agents can delay or prevent the need for ocular surgery which is often used to lower the dangerously raised IOP. This research survey was therefore directed at identifying agents from the literature that demonstrated ocular hypotensive activity, normalizing and unifying the data, determining their onset of action and rank ordering them on the basis of rapidity of action starting within 30-60 min and lasting up to at least 3-4 h post topical ocular dosing in different animal species. This research revealed a few health authority-approved drugs and some investigational compounds that appear to meet the necessary criteria of fast onset of action coupled with significant efficacy to reduce elevated IOP (by ≥ 20%, preferably by >30%). However, translation of the novel animal-based findings to the human conditions remains to be demonstrated but represent viable targets, especially EP2-receptor agonists (e.g. omidenepag isopropyl; AL-6598; butaprost), mixed activity serotonin/dopamine receptor agonists (e.g. cabergoline), rho kinase inhibitors (e.g. AMA0076, Y39983), CACNA2D1-gene product inhibitors (e.g. pregabalin), melatonin receptor agonists, and certain K+-channel openers (e.g. nicorandil, pinacidil). Other drug candidates and targets were also identified and will be discussed.
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Affiliation(s)
- Najam A Sharif
- Institute of Ophthalmology, University College London (UCL), London, UK; Imperial College of Science and Technology, St. Mary's Campus, London, UK; Eye-ACP Duke-National University of Singapore Medical School, Singapore; Singapore Eye Research Institute (SERI), Singapore; Department of Pharmacy Sciences, Creighton University, Omaha, NE, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Sciences Center, Fort Worth, Texas, USA; Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, Texas, USA; Ophthalmology Innovation Center, Santen Inc USA, Emeryville, CA, USA.
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Magno MS, Olafsson J, Beining M, Moschowits E, Lagali N, Wolffsohn JS, Craig JP, Vehof J, Dartt DA, Utheim TP. Risk associated with treatments for meibomian gland dysfunction. Cont Lens Anterior Eye 2023; 46:101818. [PMID: 36754735 DOI: 10.1016/j.clae.2023.101818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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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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Chen Y, Wang S, Chen S, Chen X, Han L, Zhong Q, Zhang K. Appropriate dose of intravitreal ranibizumab for ROP: a retrospective study. BMC Ophthalmol 2022; 22:271. [PMID: 35729540 PMCID: PMC9210651 DOI: 10.1186/s12886-022-02489-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 06/09/2022] [Indexed: 11/10/2022] Open
Abstract
Objective To compare the recurrence rate of retinopathy of prematurity (ROP) after treatment with 0.3 mg vs. 0.25 mg ranibizumab. Subjects All patients with ROP who underwent intravitreal injection of ranibizumab in Hainan General Hospital between January 2014 and May 2020 were included in this retrospective study. Methods Eighty-two cases (146 eyes) who received intravitreal injection of 0.25 mg ranibizumab were included in the conventional-dose group, and 59 cases (108 eyes) who received intravitreal injection of 0.3 mg ranibizumab were included in the high-dose group. The two groups were further divided into the 25-28-week, 29-31-week, 32-34-week, and 35-36-week GA subgroups. The differences between the conventional-dose group and the high-dose group in gestational age (GA), birth weight (BW), age at initial injection (weeks), incidence of systemic diseases, the recurrence rate of ROP, and age at retinal vascularization completed (weeks) were analyzed. Results GA, BW, age at initial injection, and the incidence of systemic diseases were not significantly different between the conventional-dose group and the high-dose group (p > 0.05). The recurrence rates of ROP were significantly lower in the 25-28-week, 29-31-week, and 32-34-week subgroups of the high-dose group than in the same subgroups of the conventional-dose group (p < 0.05). Within the conventional-dose group, the recurrence rate of ROP was significantly lower in the 32-34-week and 35-36-week subgroups than in the 25-28-week and 29-31-week subgroups (p < 0.05). Within the high-dose group, the recurrence rate of ROP was not significantly different between the four subgroups (p > 0.05). Retinal vascularization was completed at a later age in the 32-34-week subgroup of the high-dose group than in the 32-34-week subgroup of the conventional-dose group (p < 0.05) but was not significantly different between the two groups at any other GA range (p > 0.05). No severe ocular or systemic complications occurred in any patient. Conclusion Treatment with 0.3 mg ranibizumab can reduce the recurrence rate of ROP without prolonging retinal vascularization or causing serious systemic complications. Therefore, this dose may be an appropriate therapeutic dose for ROP.
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Affiliation(s)
- Yingying Chen
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China
| | - Shaoli Wang
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China
| | - Siying Chen
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China
| | - Xingyue Chen
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China
| | - Lizhen Han
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China
| | - Qionglei Zhong
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China.
| | - Kaiyan Zhang
- Hainan General Hospital , Hainan Affiliated Hospital Of Hainan Medical University, Xiuhua road, Hainan General Hospital, Hainan, China.
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Tribble JR, Hui F, Jöe M, Bell K, Chrysostomou V, Crowston JG, Williams PA. Targeting Diet and Exercise for Neuroprotection and Neurorecovery in Glaucoma. Cells 2021; 10:295. [PMID: 33535578 PMCID: PMC7912764 DOI: 10.3390/cells10020295] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/15/2021] [Accepted: 01/28/2021] [Indexed: 12/11/2022] Open
Abstract
Glaucoma is a leading cause of blindness worldwide. In glaucoma, a progressive dysfunction and death of retinal ganglion cells occurs, eliminating transfer of visual information to the brain. Currently, the only available therapies target the lowering of intraocular pressure, but many patients continue to lose vision. Emerging pre-clinical and clinical evidence suggests that metabolic deficiencies and defects may play an important role in glaucoma pathophysiology. While pre-clinical studies in animal models have begun to mechanistically uncover these metabolic changes, some existing clinical evidence already points to potential benefits in maintaining metabolic fitness. Modifying diet and exercise can be implemented by patients as an adjunct to intraocular pressure lowering, which may be of therapeutic benefit to retinal ganglion cells in glaucoma.
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Affiliation(s)
- James R. Tribble
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 171 64 Stockholm, Sweden; (J.R.T.); (M.J.)
| | - Flora Hui
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, VIC 3002, Australia; (F.H.); (J.G.C.)
- Department of Optometry & Vision Sciences, The University of Melbourne, Melbourne, VIC 3053, Australia
| | - Melissa Jöe
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 171 64 Stockholm, Sweden; (J.R.T.); (M.J.)
| | - Katharina Bell
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 168751, Singapore; (K.B.); (V.C.)
| | - Vicki Chrysostomou
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 168751, Singapore; (K.B.); (V.C.)
- Duke-NUS Medical School, Singapore 169857, Singapore
| | - Jonathan G. Crowston
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, VIC 3002, Australia; (F.H.); (J.G.C.)
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 168751, Singapore; (K.B.); (V.C.)
- Duke-NUS Medical School, Singapore 169857, Singapore
| | - Pete A. Williams
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 171 64 Stockholm, Sweden; (J.R.T.); (M.J.)
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Chong RS, Busoy JMF, Tan B, Yeo SW, Lee YS, Barathi AV, Crowston JG, Schmetterer L. A Minimally Invasive Experimental Model of Acute Ocular Hypertension with Acute Angle Closure Characteristics. Transl Vis Sci Technol 2020; 9:24. [PMID: 32832230 PMCID: PMC7414621 DOI: 10.1167/tvst.9.7.24] [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: 07/31/2019] [Accepted: 05/04/2020] [Indexed: 12/21/2022] Open
Abstract
Purpose To describe a minimally invasive experimental model of acute ocular hypertension (OHT) with characteristics of acute angle closure (AAC). Methods Adult C57/Bl6 mice (n = 31) were subjected to OHT in one eye using a modified circumlimbal suture technique that elevated intraocular pressure (IOP) for 30 minutes. Contralateral un-operated eyes served as controls. IOP, anterior segment optical coherence tomography, and fundus fluorescein angiography (FFA) were performed. The positive scotopic threshold response (pSTR) and a-wave and b-wave amplitudes were also evaluated. Retinal tissues were immunostained for the retinal ganglion cell (RGC) marker RBPMS and the glial marker GFAP. Results OHT eyes developed shallower anterior chambers and dilated pupils. FFA showed focal leakage in 32.2% of OHT eyes, but in none of the control eyes. pSTR was significantly reduced at week 1 in OHT eyes compared to control eyes (57.3 ± 7.2 µV vs. 106.9 ± 24.8 µV; P < 0.05), but a- and b-waves were unaffected. GFAP was upregulated in OHT eyes but not in control eyes or eyes that had been sutured without OHT. RGC density was reduced in OHT eyes after 4 weeks (3857 ± 143.8) vs. control eyes (4469 ± 176.0) (P < 0.05). Conclusions Our minimally invasive model resulted in acute OHT with characteristics of AAC in the absence of non-OHT-related neuroinflammatory changes arising from ocular injury alone. Translational Relevance This model provides a valuable approach to studying specific characteristics of a severe blinding disease in an experimental setting. Focal areas of ischemia were demonstrated, consistent with clinical studies of acute angle closure patients elsewhere, which may indicate the need for further research into how this could affect visual outcome in these patients.
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Affiliation(s)
- Rachel S Chong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Glaucoma Department, Singapore National Eye Centre, Singapore, Singapore.,Agency for Science, Technology and Research, Singapore, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Joanna M F Busoy
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Bingyao Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Sia Wey Yeo
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Ying Shi Lee
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Amutha V Barathi
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jonathan G Crowston
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore.,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore, Singapore
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Gallego-Ortega A, Norte-Muñoz M, Miralles de Imperial-Ollero JA, Bernal-Garro JM, Valiente-Soriano FJ, de la Villa Polo P, Avilés-Trigueros M, Villegas-Pérez MP, Vidal-Sanz M. Functional and morphological alterations in a glaucoma model of acute ocular hypertension. PROGRESS IN BRAIN RESEARCH 2020; 256:1-29. [PMID: 32958209 DOI: 10.1016/bs.pbr.2020.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To study short and long-term effects of acute ocular hypertension (AOHT) on inner and outer retinal layers, in adult Sprague-Dawley rats AOHT (87mmHg) was induced for 90min and the retinas were examined longitudinally in vivo with electroretinogram (ERG) recordings and optical coherent tomography (OCT) from 1 to 90 days (d). Ex vivo, the retinas were analyzed for rod (RBC) and cone (CBC) bipolar cells, with antibodies against protein kinase Cα and recoverin, respectively in cross sections, and for cones, horizontal (HZ) and ganglion (RGC) cells with antibodies against arrestin, calbindin and Brn3a, respectively in wholemounts. The inner retina thinned progressively up to 7d with no further changes, while the external retina had a normal thickness until 30d, with a 20% thinning between 30 and 90d. Functionally, the a-wave showed an initial reduction by 24h and a further reduction from 30 to 90d. All other main ERG waves were significantly reduced by 1d without significant recovery by 90d. Radial sections showed a normal population of RBCs but their terminals were reduced. The CBCs showed a progressive decrease with a loss of 56% by 30d. In wholemount retinas, RGCs diminished to 40% by 3d and to 16% by 30d without further loss. Cones diminished to 58% and 35% by 3 and 7d, respectively and further decreased between 30 and 90d. HZs showed normal values throughout the study. In conclusion, AOHT affects both the inner and outer retina, with a more pronounced degeneration of the cone than the rod pathway.
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Affiliation(s)
- Alejandro Gallego-Ortega
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - María Norte-Muñoz
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | | | - José Manuel Bernal-Garro
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Francisco Javier Valiente-Soriano
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Pedro de la Villa Polo
- Department of Systems Biology, University of Alcalá, Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria, Madrid, Spain
| | - Marcelino Avilés-Trigueros
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - María Paz Villegas-Pérez
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Manuel Vidal-Sanz
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain.
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Lakshmanan Y, Wong FSY, Yu WY, Li SZC, Choi KY, So KF, Chan HHL. Lycium Barbarum Polysaccharides Rescue Neurodegeneration in an Acute Ocular Hypertension Rat Model Under Pre- and Posttreatment Conditions. Invest Ophthalmol Vis Sci 2019; 60:2023-2033. [PMID: 31067322 DOI: 10.1167/iovs.19-26752] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the posttreatment neuronal rescue effects of Lycium barbarum polysaccharides (LBP) in an acute ocular hypertensive (AOH) model. Methods Intraocular pressure (IOP) was elevated manometrically to 80 mm Hg (AOH) or 15 mm Hg (sham) for 120 minutes in adult Sprague-Dawley rats. Five experimental groups were considered: Three AOH groups were pretreated with PBS (vehicle) (n = 9), LBP 1 mg/kg (n = 8), or 10 mg/kg (n = 13), and one AOH group was posttreated with LBP 10 mg/kg (n = 8), once daily. The sham cannulation group (n = 5) received no treatment. Pretreatments commenced 7 days before and posttreatment 6 hours after AOH, and continued up through postcannulation day 28. All the animals underwent optical coherence tomography and electroretinogram measurements at baseline and postcannulation days 10 and 28. The ganglion cell layer (GCL) densities were quantified at day 28. Results Both inner retinal layer thickness (IRLT) and positive scotopic threshold response (pSTR) underwent significant reduction (≥50% of thickness and amplitude) in the vehicle group (P < 0.05). Pretreatment with LBP 1 and 10 mg/kg retained 77 ± 11% and 89 ± 8% of baseline IRLT, respectively, and preserved pSTR functions. The posttreatment group showed a significant reduction in IRLT (-35 ± 8%, P < 0.001) and pSTR (∼48% of baseline, P < 0.001) on day 10. By day 28, there was an improvement in functional pSTR (∼72% of baseline, P > 0.05) with no significant further thinning (-40 ± 8%, P = 0.15) relative to day 10. GCL density was reduced in vehicle control (P = 0.0001), but did not differ between sham and pre- and posttreated AOH groups. Conclusions The rescue effect of LBP posttreatment was observed later, which arrested the secondary degeneration and improved the retinal function.
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Affiliation(s)
- Yamunadevi Lakshmanan
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Francisca Siu-Yin Wong
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Wing-Yan Yu
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Serena Zhe-Chuang Li
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Kai-Yip Choi
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Kwok-Fai So
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,Guangdong-Hongkong-Macau (GHM) Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Henry Ho-Lung Chan
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
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11
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Pi S, Hormel TT, Wei X, Cepurna W, Camino A, Guo Y, Huang D, Morrison J, Jia Y. Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography. NEUROPHOTONICS 2019; 6:041104. [PMID: 31312671 PMCID: PMC6624745 DOI: 10.1117/1.nph.6.4.041104] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/21/2019] [Indexed: 05/08/2023]
Abstract
Elevated intraocular pressure (IOP) is an important risk factor for glaucoma. However, the role of IOP in glaucoma progression, as well as retinal physiology in general, remains incompletely understood. We demonstrate the use of visible light optical coherence tomography to measure retinal responses to acute IOP elevation in Brown Norway rats. We monitored retinal responses in reflectivity, angiography, blood flow, oxygen saturation ( sO 2 ), and oxygen metabolism over a range of IOP from 10 to 100 mmHg. As IOP was elevated, nerve fiber layer reflectivity was found to decrease. Vascular perfusion in the three retinal capillary plexuses remained steady until IOP exceeded 70 mmHg and arterial flow was noted to reverse periodically at high IOPs. However, a significant drop in total retinal blood flow was observed first at 40 mmHg. As IOP increased, the venous sO 2 demonstrated a gradual decrease despite steady arterial sO 2 , which is consistent with increased arterial-venous oxygen extraction across the retinal capillary beds. Calculated total retinal oxygen metabolism was steady, reflecting balanced responses of blood flow and oxygen extraction, until IOP exceeded 40 mmHg, and fell to 0 at 70 and 80 mmHg. Above this, measurements were unattainable. All measurements reverted to baseline when the IOP was returned to 10 mmHg, indicating good recovery following acute pressure challenge. These results demonstrate the ability of this system to monitor retinal oxygen metabolism noninvasively and how it can help us understand retinal responses to elevated IOP.
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Affiliation(s)
- Shaohua Pi
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Tristan T. Hormel
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Xiang Wei
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - William Cepurna
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Acner Camino
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Yukun Guo
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - David Huang
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - John Morrison
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Yali Jia
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
- Address all correspondence to Yali Jia, E-mail:
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Kato A, Okamoto Y, Okamoto F, Saito M, Miyazono Y, Oshika T. Short-term intraocular pressure changes after intravitreal injection of bevacizumab for retinopathy of prematurity. Jpn J Ophthalmol 2019; 63:262-268. [DOI: 10.1007/s10384-019-00661-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 12/21/2018] [Indexed: 11/25/2022]
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13
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Fry LE, Fahy E, Chrysostomou V, Hui F, Tang J, van Wijngaarden P, Petrou S, Crowston JG. The coma in glaucoma: Retinal ganglion cell dysfunction and recovery. Prog Retin Eye Res 2018; 65:77-92. [DOI: 10.1016/j.preteyeres.2018.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/18/2018] [Accepted: 04/03/2018] [Indexed: 01/07/2023]
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Liu HH, Zhang L, Shi M, Chen L, Flanagan JG. Comparison of laser and circumlimbal suture induced elevation of intraocular pressure in albino CD-1 mice. PLoS One 2017; 12:e0189094. [PMID: 29190824 PMCID: PMC5708743 DOI: 10.1371/journal.pone.0189094] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/18/2017] [Indexed: 12/23/2022] Open
Abstract
Animal models of ocular hypertension are important tools for glaucoma studies. Both acute transient models and chronic models of ocular hypertension may be useful to investigate specific aspects of neurodegeneration. In this study, we compare the intraocular pressure (IOP) and inner retinal changes induced by 1) laser photocoagulation of both episcleral veins and limbal vessels and 2) circumlimbal suture in CD-1 mice. The suture group is divided into 3 subgroups depending on the level of the immediate IOP spike (acute > 55 mmHg or chronic < 55 mmHg) and time period of monitoring (7 or 28 days). The laser group is followed for 7 days. IOP data show that it peaks at 5 hours and returns to normal level within 7 days in the laser group. In all suture groups, IOP spikes initially and decreases gradually, but it remains significantly elevated at 7 days. In 7 days, the acute suture model generates rapid loss of retinal nerve fiber layer (RNFL) and retinal ganglion cells (RGCs) when compared to the gradual loss by the chronic suture model, possibly due to retinal ischemia and reperfusion within the first few hours after treatment. The laser model falls between the acute suture and chronic suture models resulting in less RNFL and RGC loss than the acute suture model but significantly more loss than the chronic suture model. These results suggest that when using suture models of IOP elevation, it is critical to take the initial IOP spike into consideration and to choose between the acute and chronic models depending on respective research purposes.
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Affiliation(s)
- Hsin-Hua Liu
- School of Optometry and Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Vision Science Graduate Program, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Liwei Zhang
- School of Optometry and Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Vision Science Graduate Program, University of California, Berkeley, California, United States of America
| | - Meng Shi
- School of Optometry and Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Vision Science Graduate Program, University of California, Berkeley, California, United States of America
| | - Lu Chen
- School of Optometry and Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Vision Science Graduate Program, University of California, Berkeley, California, United States of America
| | - John G. Flanagan
- School of Optometry and Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Vision Science Graduate Program, University of California, Berkeley, California, United States of America
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15
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Ocular fundus pulsations within the posterior rat eye: Chorioscleral motion and response to elevated intraocular pressure. Sci Rep 2017; 7:8780. [PMID: 28821834 PMCID: PMC5562765 DOI: 10.1038/s41598-017-09310-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/25/2017] [Indexed: 12/13/2022] Open
Abstract
A multi-functional optical coherence tomography (OCT) approach is presented to determine ocular fundus pulsations as an axial displacement between the retina and the chorioscleral complex in the albino rat eye. By combining optical coherence elastography and OCT angiography (OCTA), we measure subtle deformations in the nanometer range within the eye and simultaneously map retinal and choroidal perfusion. The conventional OCT reflectivity contrast serves as a backbone to segment the retina and to define several slabs which are subsequently used for quantitative ocular pulsation measurements as well as for a qualitative exploration of the multi-functional OCT image data. The proposed concept is applied in healthy albino rats as well as in rats under acute elevation of the intraocular pressure (IOP). The evaluation of this experiment revealed an increased pulsatility and deformation between the retinal and chorioscleral complex while increasing the IOP level from 15 mmHg to 65 mmHg. At IOP levels exceeding 65 mmHg, the pulsatility decreased significantly and retinal as well as choroidal perfusion vanished in OCTA. Furthermore, the evaluation of the multi-parametric experiment revealed a spatial correlation between fundus pulsatility and choroidal blood flow. This indicates that the assessed pulsatility may be a valuable parameter describing the choroidal perfusion.
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Morrison JC, Cepurna WO, Tehrani S, Choe TE, Jayaram H, Lozano DC, Fortune B, Johnson EC. A Period of Controlled Elevation of IOP (CEI) Produces the Specific Gene Expression Responses and Focal Injury Pattern of Experimental Rat Glaucoma. Invest Ophthalmol Vis Sci 2017; 57:6700-6711. [PMID: 27942722 PMCID: PMC5156512 DOI: 10.1167/iovs.16-20573] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We determine if several hours of controlled elevation of IOP (CEI) will produce the optic nerve head (ONH) gene expression changes and optic nerve (ON) damage pattern associated with early experimental glaucoma in rats. Methods The anterior chambers of anesthetized rats were cannulated and connected to a reservoir to elevate IOP. Physiologic parameters were monitored. Following CEI at various recovery times, ON cross-sections were graded for axonal injury. Anterior ONHs were collected at 0 hours to 10 days following CEI and RNA extracted for quantitative PCR measurement of selected messages. The functional impact of CEI was assessed by electroretinography (ERG). Results During CEI, mean arterial pressure (99 ± 6 mm Hg) and other physiologic parameters remained stable. An 8-hour CEI at 60 mm Hg produced significant focal axonal degeneration 10 days after exposure, with superior lesions in 83% of ON. Message analysis in CEI ONH demonstrated expression responses previously identified in minimally injured ONH following chronic IOP elevation, as well as their sequential patterns. Anesthesia with cannulation at 20 mm Hg did not alter these message levels. Electroretinographic A- and B-waves, following a significant reduction at 2 days after CEI, were fully recovered at 2 weeks, while peak scotopic threshold response (pSTR) remained mildly but significantly depressed. Conclusions A single CEI reproduces ONH message changes and patterns of ON injury previously observed with chronic IOP elevation. Controlled elevation of IOP can allow detailed determination of ONH cellular and functional responses to an injurious IOP insult and provide a platform for developing future therapeutic interventions.
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Affiliation(s)
- John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - William O Cepurna
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Shandiz Tehrani
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Tiffany E Choe
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Hari Jayaram
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States 2Glaucoma Service, NIHR Moorfields Biomedical Research Centre, London, United Kingdom
| | - Diana C Lozano
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute, Portland, Oregon, United States
| | - Elaine C Johnson
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
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Sun D, Moore S, Jakobs TC. Optic nerve astrocyte reactivity protects function in experimental glaucoma and other nerve injuries. J Exp Med 2017; 214:1411-1430. [PMID: 28416649 PMCID: PMC5413323 DOI: 10.1084/jem.20160412] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 12/05/2016] [Accepted: 03/08/2017] [Indexed: 01/06/2023] Open
Abstract
Reactive remodeling of optic nerve head astrocytes is consistently observed in glaucoma and other optic nerve injuries. However, it is unknown whether this reactivity is beneficial or harmful for visual function. In this study, we used the Cre recombinase (Cre)-loxP system under regulation of the mouse glial fibrillary acidic protein promoter to knock out the transcription factor signal transducer and activator of transcription 3 (STAT3) from astrocytes and test the effect this has on reactive remodeling, ganglion cell survival, and visual function after experimental glaucoma and nerve crush. After injury, STAT3 knockout mice displayed attenuated astrocyte hypertrophy and reactive remodeling; astrocytes largely maintained their honeycomb organization and glial tubes. These changes were associated with increased loss of ganglion cells and visual function over a 30-day period. Thus, reactive astrocytes play a protective role, preserving visual function. STAT3 signaling is an important mediator of various aspects of the reactive phenotype within optic nerve astrocytes.
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Affiliation(s)
- Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114
| | - Sara Moore
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114
| | - Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114
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18
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Zhao D, Nguyen CTO, Wong VHY, Lim JKH, He Z, Jobling AI, Fletcher EL, Chinnery HR, Vingrys AJ, Bui BV. Characterization of the Circumlimbal Suture Model of Chronic IOP Elevation in Mice and Assessment of Changes in Gene Expression of Stretch Sensitive Channels. Front Neurosci 2017; 11:41. [PMID: 28239332 PMCID: PMC5301305 DOI: 10.3389/fnins.2017.00041] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/19/2017] [Indexed: 12/30/2022] Open
Abstract
To consider whether a circumlimbal suture can be used to chronically elevate intraocular pressure (IOP) in mice and to assess its effect on retinal structure, function and gene expression of stretch sensitive channels. Anesthetized adult C57BL6/J mice had a circumlimbal suture (10/0) applied around the equator of one eye. In treated eyes (n = 23) the suture was left in place for 12 weeks whilst in sham control eyes the suture was removed at day two (n = 17). Contralateral eyes served as untreated controls. IOP was measured after surgery and once a week thereafter. After 12 weeks, electroretinography (ERG) was performed to assess photoreceptor, bipolar cell and retinal ganglion cell (RGC) function. Retinal structure was evaluated using optical coherence tomography. Retinae were processed for counts of ganglion cell density or for quantitative RT-PCR to quantify purinergic (P2x7, Adora3, Entpd1) or stretch sensitive channel (Panx1, Trpv4) gene expression. Immediately after suture application, IOP spiked to 33 ± 3 mmHg. After 1 day, IOP had recovered to 27 ± 3 mmHg. Between weeks 2 and 12, IOP remained elevated above baseline (control 14 ± 1 mmHg, ocular hypertensive 19 ± 1 mmHg). Suture removal at day 2 (Sham) restored IOP to baseline levels, where it remained through to week 12. ERG analysis showed that 12 weeks of IOP elevation reduced photoreceptor (−15 ± 4%), bipolar cell (−15 ± 4%) and ganglion cell responses (−19 ± 6%) compared to sham controls and respective contralateral eyes (untreated). The retinal nerve fiber layer was thinned in the presence of normal total retinal thickness. Ganglion cell density was reduced across all quadrants (superior −12 ± 5%; temporal, −7% ± 2%; inferior −9 ± 4%; nasal −8 ± 5%). Quantitative RT-PCR revealed a significant increase in Entpd1 gene expression (+11 ± 4%), whilst other genes were not significantly altered (P2x7, Adora3, Trpv4, Panx1). Our results show that circumlimbal ligation produces mild chronic ocular hypertension and retinal dysfunction in mice. Consistent with a sustained change to purinergic signaling we found an up-regulation of Entpd1.
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Affiliation(s)
- Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Jeremiah K H Lim
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, University of Melbourne Parkville, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne Parkville, VIC, Australia
| | - Holly R Chinnery
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
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Hasegawa T, Ooto S, Takayama K, Makiyama Y, Akagi T, Ikeda HO, Nakanishi H, Suda K, Yamada H, Uji A, Yoshimura N. Cone Integrity in Glaucoma: An Adaptive-Optics Scanning Laser Ophthalmoscopy Study. Am J Ophthalmol 2016; 171:53-66. [PMID: 27565227 DOI: 10.1016/j.ajo.2016.08.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 12/14/2022]
Abstract
PURPOSE To investigate photoreceptor changes in eyes with glaucoma. DESIGN Cross-sectional study. METHODS The study included 35 eyes of 35 patients with primary open-angle glaucoma who had suffered parafoveal visual field loss at least 3 years previously, as well as 21 eyes of 21 normal subjects. Eyes with an axial length ≥26.0 mm were excluded. All subjects underwent a full ophthalmologic examination, including spectral-domain optical coherence tomography (SDOCT) and prototype adaptive-optics scanning laser ophthalmoscopy (AO-SLO) imaging. RESULTS As determined using AO-SLO, eyes with glaucoma did not differ significantly from normal eyes in terms of either cone density (26 468 ± 3392 cones/m2 vs 26 147 ± 2700 cones/m2, respectively; P = .77; measured 0.5 mm from the foveal center) or cone spatial organization (ratio of hexagonal Voronoi domain: 43.7% ± 4.4% vs 44.3% ± 4.9%; P = .76; measured 0.5 mm from the foveal center). Furthermore, SDOCT showed that the 2 groups did not differ significantly in terms of the photoreceptor-related layer thickness, and that the photoreceptor ellipsoid zone band was continuous in all normal and glaucoma eyes. In glaucoma eyes with vertically asymmetric severity, the more affected side did not significantly differ from the less affected side in terms of cone density, cone spatial organization, or photoreceptor-related layer thickness. In 8 eyes (22.9%) with glaucoma, dark, partition-like areas surrounded the cones on the AO-SLO. CONCLUSIONS Both AO-SLO and SDOCT showed cone integrity in eyes with glaucoma, even in areas with visual field and nerve fiber loss. In AO-SLO, microcystic lesions in the inner nuclear layer may influence images of the cone mosaic.
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Intraoperative electrophysiological evaluations of macular function during peripheral scleral indentation. Sci Rep 2016; 6:35164. [PMID: 27762313 PMCID: PMC5071826 DOI: 10.1038/srep35164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 09/26/2016] [Indexed: 11/08/2022] Open
Abstract
Scleral indentation is widely used to examine the peripheral fundus, however it can increase the intraocular pressure (IOP) to high levels which can then affect retinal function. We evaluated the effects of scleral indentation on the macular function electrophysiologically. Intraoperative focal macular electroretinograms (iFMERGs) were recorded with and without controlling the IOP in 7 eyes. Without IOP control, the IOP increased from 21.7 ± 4.9 to 92.7 ± 20.2 mmHg significantly (P = 0.020) and the amplitudes of the b-wave (from 6.29 ± 1.160 to 3.71 ± 1.98 uV, P = 0.007), on-photopic negative response (from 2.29 ± 0.99 to 0.72 ± 0.47 uV, on-PhNR, P = 0.005), and d-wave (from 2.57 ± 0.41 to 1.64 ± 0.69 uV, P = 0.007) decreased significantly soon after beginning the indentation. All values returned to the baseline levels after releasing the indentation. In the eyes with IOP controlled, the IOP and the amplitude of all components did not change significantly during and after the indentation except the on-PhNR amplitude which was significantly reduced during the indentation. The changes in the iFMERGs and macular function caused by scleral indentation were transient and reversible. The changes can be minimized by controlling the IOP.
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21
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Shen HH, Liu GS, Chow SH, Wang JH, He Z, Nguyen C, Lin TW, Bui BV. Intraocular Pressure Induced Retinal Changes Identified Using Synchrotron Infrared Microscopy. PLoS One 2016; 11:e0164035. [PMID: 27711151 PMCID: PMC5053542 DOI: 10.1371/journal.pone.0164035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 09/19/2016] [Indexed: 11/18/2022] Open
Abstract
Infrared (IR) spectroscopy has been used to quantify chemical and structural characteristics of a wide range of materials including biological tissues. In this study, we examined spatial changes in the chemical characteristics of rat retina in response to intraocular pressure (IOP) elevation using synchrotron infrared microscopy (SIRM), a non-destructive imaging approach. IOP elevation was induced by placing a suture around the eye of anaesthetised rats. Retinal sections were collected onto transparent CaF2 slides 10 days following IOP elevation. Using combined SIRM spectra and chemical mapping approaches it was possible to quantify IOP induced changes in protein conformation and chemical distribution in various layers of the rat retina. We showed that 10 days following IOP elevation there was an increase in lipid and protein levels in the inner nuclear layer (INL) and ganglion cell layer (GCL). IOP elevation also resulted in an increase in nucleic acids in the INL. Analysis of SIRM spectra revealed a shift in amide peaks to lower vibrational frequencies with a more prominent second shoulder, which is consistent with the presence of cell death in specific layers of the retina. These changes were more substantial in the INL and GCL layers compared with those occurring in the outer nuclear layer. These outcomes demonstrate the utility of SIRM to quantify the effect of IOP elevation on specific layers of the retina. Thus SIRM may be a useful tool for the study of localised tissue changes in glaucoma and other eye diseases.
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Affiliation(s)
- Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, Australia
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- * E-mail: (HHS); (BVB)
| | - Guei-Sheung Liu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Seong Hoong Chow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Jiang-Hui Wang
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Zheng He
- Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Christine Nguyen
- Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Tsung-Wu Lin
- Department of Chemistry, Tunghai University, Taichung City, Taiwan
| | - Bang V. Bui
- Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
- * E-mail: (HHS); (BVB)
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22
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Choh V, Gurdita A, Tan B, Prasad RC, Bizheva K, Joos KM. Short-Term Moderately Elevated Intraocular Pressure Is Associated With Elevated Scotopic Electroretinogram Responses. Invest Ophthalmol Vis Sci 2016; 57:2140-51. [PMID: 27100161 PMCID: PMC4849866 DOI: 10.1167/iovs.15-18770] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose Moderately elevated intraocular pressure (IOP) is a risk factor for open-angle glaucoma. Some patients suffer glaucoma despite clinically measured normal IOPs. Fluctuations in IOP may have a significant role since IOPs are higher during sleep and inversion activities. Controlled transient elevations of IOPs in rats over time lead to optic nerve structural changes that are similar to the early changes observed in constant chronic models of glaucoma. Because early intervention decreases glaucoma progression, this study was done to determine if early physiological changes to the retina could be detected with noninvasive electrophysiological and optical imaging tests during moderately elevated IOP. Methods Intraocular pressures were raised to moderately high levels (35 mm Hg) in one eye of Sprague-Dawley rats while the other (control) eye was untreated. One group of rats underwent scotopic threshold response (STR) and electroretinogram (ERG) testing, while another 3 groups underwent optical coherence tomography (OCT) imaging, Western blot, or histologic evaluation. Results The amplitudes of the STR and ERG responses in eyes with moderately elevated IOPs were enhanced compared to the values before IOP elevation, and compared to untreated contralateral eyes. Structural changes to the optic nerve also occurred during IOP elevation. Conclusions Although ischemic IOP elevations are well-known to globally reduce components of the scotopic ERG, acute elevation in rats to levels often observed in untreated glaucoma patients caused an increase in these parameters. Further exploration of these phenomena may be helpful in better understanding the mechanisms mediating early retinal changes during fluctuating or chronically elevated IOP.
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Affiliation(s)
- Vivian Choh
- School of Optometry and Vision Science University of Waterloo, Waterloo, Ontario, Canada
| | - Akshay Gurdita
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Bingyao Tan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Ratna C Prasad
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, Tennessee, United States
| | - Kostadinka Bizheva
- School of Optometry and Vision Science University of Waterloo, Waterloo, Ontario, Canada 2Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Karen M Joos
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, Tennessee, United States
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Abstract
PURPOSE OF REVIEW Electrophysiological measures of vision function have for decades generated interest among glaucoma researchers and clinicians alike because of their potential to help elucidate pathophysiological processes and sequence of glaucomatous damage, as well as to offer a potential complementary metric of function that might be more sensitive than standard automated perimetry. The purpose of this article is to review the recent literature to provide an update on the role of the electroretinogram (ERG) in glaucoma diagnosis. RECENT FINDINGS The pattern reversal ERG (PERG) and the photopic negative response (PhNR) of the cone-driven full-field, focal or multifocal ERG provide objective measures of retinal ganglion cell function and are all sensitive to glaucomatous damage. Recent studies demonstrate that a reduced PERG amplitude is predictive of subsequent visual field conversion (from normal to glaucomatous) and an increased rate of progressive retinal nerve fiber layer thinning in suspect eyes, indicating a potential role for PERG in risk stratification. Converging evidence indicates that some portion of PERG and PhNR abnormality represents a reversible aspect of dysfunction in glaucoma. SUMMARY PERG and PhNR responses obtained from the central macula are capable of detecting early-stage, reversible glaucomatous dysfunction.
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Fu L, Lo ACY, Lai JSM, Shih KC. Comparison of electroretinographic responses between two different age groups of adult Dark Agouti rats. Int J Ophthalmol 2015; 8:898-903. [PMID: 26558198 DOI: 10.3980/j.issn.2222-3959.2015.05.08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/05/2015] [Indexed: 11/02/2022] Open
Abstract
AIM To describe and compare the differences in electroretinographic responses between two different age groups of adult Dark Agouti (DA) rats and to better understand the effect of age on retinal histology and function. METHODS The electroretinographic responses of two different age groups of adult DA rats were compared. Animals were divided into younger adult DA rats 10-12wk (n=8) and older adult DA rats 17-19wk (n=8). Full field electroretinography (ERG) was recorded simultaneously from both eyes after dark adaption and light adaption and parameters including the positive scotopic threshold response (pSTR), negative scotopic threshold response (nSTR), scotopic a-wave, b-wave, photopic a-wave, b-wave and photopic negative response (PhNR) were compared between groups. RESULTS The older adult rats displayed lower stimulation thresholds of the STRs (pSTR and nSTR) and higher amplitudes of pSTR, scotopic a-wave and b-wave, photopic b-wave and PhNR amplitudes, with shorter implicit times. Photopic a-wave amplitudes were however higher in the younger adult rats. CONCLUSION In summary, for the rod system, photoreceptor, bipolar cell and RGC activity was enhanced in the older adult rats. For the cone system, RGC and bipolar cell activity was enhanced, while photoreceptor activity was depressed in the older adult rats. Such age-related selective modification of retinal cell function needs to be considered when conducting ophthalmic research in adult rats.
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Affiliation(s)
- Lin Fu
- Department of Ophthalmology, LKS Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Amy Cheuk Yin Lo
- Department of Ophthalmology, LKS Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Jimmy Shiu Ming Lai
- Department of Ophthalmology, LKS Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kendrick Co Shih
- Department of Ophthalmology, LKS Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong, China
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Zhi Z, Cepurna W, Johnson E, Jayaram H, Morrison J, Wang RK. Evaluation of the effect of elevated intraocular pressure and reduced ocular perfusion pressure on retinal capillary bed filling and total retinal blood flow in rats by OMAG/OCT. Microvasc Res 2015; 101:86-95. [PMID: 26186381 DOI: 10.1016/j.mvr.2015.07.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/04/2015] [Accepted: 07/04/2015] [Indexed: 01/01/2023]
Abstract
PURPOSE To determine if retinal capillary filling is preserved in the face of acutely elevated intraocular pressure (IOP) in anesthetized rats, despite a reduction in total retinal blood flow (RBF), using optical microangiography/optical coherence tomography (OMAG/OCT). METHODS OMAG provided the capability of depth-resolved imaging of the retinal microvasculature down to the capillary level. Doppler OCT was applied to measure the total RBF using an enface integration approach. The microvascular pattern, capillary density, and total RBF were monitored in vivo as the IOP was increased from 10 to 100mmHg in 10mmHg intervals and returned back to 10mmHg. RESULTS In animals with mean arterial pressure (MAP) of 102±4mmHg (n=10), when IOP was increased from 0 to 100mmHg, the capillary density remained at or above 80% of baseline for the IOP up to 60mmHg [or ocular perfusion pressure (OPP) at 40mmHg]. This was then decreased, achieving 60% of baseline at IOP 70mmHg and OPP of 30mmHg. Total RBF was unaffected by moderate increases in IOP up to 30mmHg, beyond which total RBF decreased linearly, reaching 50% of baseline at IOP 60mmHg and OPP 40mmHg. Both capillary density and total RBF were totally extinguished at 100mmHg, but fully recovered when IOP returned to baseline. By comparison, a separate group of animals with lower MAP (mean=75±6mmHg, n=7) demonstrated comparable decreases in both capillary filling and total RBF at IOPs that were 20mmHg lower than in the initial group. Both were totally extinguished at 80mmHg, but fully recovered when IOP returned to baseline. Relationships of both parameters to OPP were unchanged. CONCLUSION Retinal capillary filling and total RBF responses to IOP elevation can be monitored non-invasively by OMAG/OCT and both are influenced by OPP. Retinal capillary filling was relatively preserved down to a perfusion pressure of 40mmHg, despite a linear reduction in total RBF.
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Affiliation(s)
- Zhongwei Zhi
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - William Cepurna
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Elaine Johnson
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Hari Jayaram
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - John Morrison
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA.
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Fortune B. In vivo imaging methods to assess glaucomatous optic neuropathy. Exp Eye Res 2015; 141:139-53. [PMID: 26048475 DOI: 10.1016/j.exer.2015.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 05/13/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
Abstract
The goal of this review is to summarize the most common imaging methods currently applied for in vivo assessment of ocular structure in animal models of experimental glaucoma with an emphasis on translational relevance to clinical studies of the human disease. The most common techniques in current use include optical coherence tomography and scanning laser ophthalmoscopy. In reviewing the application of these and other imaging modalities to study glaucomatous optic neuropathy, this article is organized into three major sections: 1) imaging the optic nerve head, 2) imaging the retinal nerve fiber layer and 3) imaging retinal ganglion cell soma and dendrites. The article concludes with a brief section on possible future directions.
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Affiliation(s)
- Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, 1225 NE Second Avenue, Portland, OR 97232, USA.
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Abbott CJ, Choe TE, Burgoyne CF, Cull G, Wang L, Fortune B. Comparison of retinal nerve fiber layer thickness in vivo and axonal transport after chronic intraocular pressure elevation in young versus older rats. PLoS One 2014; 9:e114546. [PMID: 25501362 PMCID: PMC4263742 DOI: 10.1371/journal.pone.0114546] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 11/11/2014] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. RESULTS Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77-80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75-95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). CONCLUSION Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age.
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Affiliation(s)
- Carla J. Abbott
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Tiffany E. Choe
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Claude F. Burgoyne
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Grant Cull
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Lin Wang
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
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Khan AK, Tse DY, van der Heijden ME, Shah P, Nusbaum DM, Yang Z, Wu SM, Frankfort BJ. Prolonged elevation of intraocular pressure results in retinal ganglion cell loss and abnormal retinal function in mice. Exp Eye Res 2014; 130:29-37. [PMID: 25450059 DOI: 10.1016/j.exer.2014.11.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/24/2014] [Accepted: 11/12/2014] [Indexed: 12/25/2022]
Abstract
The purpose of this study was to assess the impact of prolonged intraocular pressure (IOP) elevation on retinal anatomy and function in a mouse model of experimental glaucoma. IOP was elevated by anterior chamber injection of a fixed combination of polystyrene beads and sodium hyaluronate, and maintained via re-injection after 24 weeks. IOP was measured weekly with a rebound tonometer for 48 weeks. Histology was assessed with a combination of retrograde labeling and antibody staining. Retinal physiology and function was assessed with dark-adapted electroretinograms (ERGs). Comparisons between bead-injected animals and various controls were conducted at both 24 and 48 weeks after bead injection. IOP was elevated throughout the study. IOP elevation resulted in a reduction of retinal ganglion cell (RGCs) and an increase in axial length at both 24 and 48 weeks after bead injection. The b-wave amplitude of the ERG was increased to the same degree in bead-injected eyes at both time points, similar to previous studies. The positive scotopic threshold response (pSTR) amplitude, a measure of RGC electrical function, was diminished at both 24 and 48 weeks when normalized to the increased b-wave amplitude. At 48 weeks, the pSTR amplitude was reduced even without normalization, suggesting more profound RGC dysfunction. We conclude that injection of polystyrene beads and sodium hyaluronate causes chronic IOP elevation which results in phenotypes of stable b-wave amplitude increase and progressive pSTR amplitude reduction, as well as RGC loss and axial length elongation.
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Affiliation(s)
- A Kareem Khan
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Dennis Y Tse
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA; School of Optometry, Hong Kong Polytechnic University, Hong Kong
| | - Meike E van der Heijden
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Priya Shah
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Derek M Nusbaum
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Zhuo Yang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Samuel M Wu
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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Abbott CJ, Choe TE, Lusardi TA, Burgoyne CF, Wang L, Fortune B. Evaluation of retinal nerve fiber layer thickness and axonal transport 1 and 2 weeks after 8 hours of acute intraocular pressure elevation in rats. Invest Ophthalmol Vis Sci 2014; 55:674-87. [PMID: 24398096 DOI: 10.1167/iovs.13-12811] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PURPOSE To compare in vivo retinal nerve fiber layer thickness (RNFLT) and axonal transport at 1 and 2 weeks after an 8-hour acute IOP elevation in rats. METHODS Forty-seven adult male Brown Norway rats were used. Procedures were performed under anesthesia. The IOP was manometrically elevated to 50 mm Hg or held at 15 mm Hg (sham) for 8 hours unilaterally. The RNFLT was measured by spectral-domain optical coherence tomography. Anterograde and retrograde axonal transport was assessed from confocal scanning laser ophthalmoscopy imaging 24 hours after bilateral injections of 2 μL 1% cholera toxin B-subunit conjugated to AlexaFluor 488 into the vitreous or superior colliculi, respectively. Retinal ganglion cell (RGC) and microglial densities were determined using antibodies against Brn3a and Iba-1. RESULTS The RNFLT in experimental eyes increased from baseline by 11% at 1 day (P < 0.001), peaked at 19% at 1 week (P < 0.0001), remained 11% thicker at 2 weeks (P < 0.001), recovered at 3 weeks (P > 0.05), and showed no sign of thinning at 6 weeks (P > 0.05). There was no disruption of anterograde transport at 1 week (superior colliculi fluorescence intensity, 75.3 ± 7.9 arbitrary units [AU] for the experimental eyes and 77.1 ± 6.7 AU for the control eyes) (P = 0.438) or 2 weeks (P = 0.188). There was no obstruction of retrograde transport at 1 week (RCG density, 1651 ± 153 per mm(2) for the experimental eyes and 1615 ± 135 per mm(2) for the control eyes) (P = 0.63) or 2 weeks (P = 0.25). There was no loss of Brn3a-positive RGC density at 6 weeks (P = 0.74) and no increase in microglial density (P = 0.92). CONCLUSIONS Acute IOP elevation to 50 mm Hg for 8 hours does not cause a persisting axonal transport deficit at 1 or 2 weeks or a detectable RNFLT or RGC loss by 6 weeks but does lead to transient RNFL thickening that resolves by 3 weeks.
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Affiliation(s)
- Carla J Abbott
- Discoveries in Sight Research Laboratories, Legacy Good Samaritan Devers Eye Institute, and Legacy Research Institute, Legacy Health, Portland, Oregon
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