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Nork TM, Kim CBY, Katz AW, Rasmussen CA, Banghart M, Ver Hoeve JN. Multifocal electroretinography increases following experimental glaucoma in nonhuman primates with retinal ganglion cell axotomy. Doc Ophthalmol 2023; 146:97-112. [PMID: 36763214 PMCID: PMC10284020 DOI: 10.1007/s10633-023-09922-1] [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: 11/18/2021] [Accepted: 01/20/2023] [Indexed: 02/11/2023]
Abstract
PURPOSE To determine whether short-latency changes in multifocal electroretinography (mfERG) observed in experimental glaucoma (EG) are secondary solely to retinal ganglion cell (RGC) loss or whether there is a separate contribution from elevated intraocular pressure (IOP). METHODS Prior to operative procedures, a series of baseline mfERGs were recorded from six rhesus macaques using a 241-element unstretched stimulus. Animals then underwent hemiretinal endodiathermy axotomy (HEA) by placing burns along the inferior 180° of the optic nerve margin in the right eye (OD). mfERG recordings were obtained in each animal at regular intervals following for 3-4 months to allow stabilization of the HEA effects. Laser trabecular meshwork destruction (LTD) to elevate IOP was then performed; first-order kernel (K1) waveform root-mean-square (RMS) amplitudes for the short-latency segment of the mfERG wave (9-35 ms) were computed for two 7-hexagon groupings-the first located within the superior (non-axotomized) macula and the second within the inferior (axotomized) macula. Immunohistochemistry for glial fibrillary acidic protein (GFAP) was done. RESULTS By 3 months post HEA, there was marked thinning of the inferior nerve fiber layer as measured by optical coherence tomography. Compared with baseline, no statistically significant changes in 9-35 ms K1 RMS amplitudes were evident in either the axotomized or non-axotomized portions of the macula. Following LTD, mean IOP in HEA eyes rose to 46 ± 9 compared with 20 ± 2 mmHg (SD) in the fellow control eyes. In the HEA + EG eyes, statistically significant increases in K1 RMS amplitude were present in both the axotomized inferior and non-axotomized superior portions of the OD retinas. No changes in K1 RMS amplitude were found in the fellow control eyes from baseline to HEA epoch, but there was a smaller increase from baseline to HEA + EG. Upregulation of GFAP in the Müller cells was evident in both non-axotomized and axotomized retina in eyes with elevated IOP. CONCLUSIONS The RMS amplitudes of the short-latency mfERG K1 waveforms are not altered following axotomy but undergo marked increases following elevated IOP. This suggests that the increase in mfERG amplitude was not solely a result of RGC loss and may reflect photoreceptor and bipolar cell dysfunction and/or changes in Müller cells.
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Affiliation(s)
- T Michael Nork
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
| | - Charlene B Y Kim
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Alexander W Katz
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Carol A Rasmussen
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Mark Banghart
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - James N Ver Hoeve
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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Raghunathan V, Eaton JS, Christian BJ, Morgan JT, Ver Hoeve JN, Yang CYC, Gong H, Rasmussen CA, Miller PE, Russell P, Nork TM, Murphy CJ. Biomechanical, ultrastructural, and electrophysiological characterization of the non-human primate experimental glaucoma model. Sci Rep 2017; 7:14329. [PMID: 29085025 PMCID: PMC5662689 DOI: 10.1038/s41598-017-14720-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/13/2017] [Indexed: 11/08/2022] Open
Abstract
Laser-induced experimental glaucoma (ExGl) in non-human primates (NHPs) is a common animal model for ocular drug development. While many features of human hypertensive glaucoma are replicated in this model, structural and functional changes in the unlasered portions of trabecular meshwork (TM) of laser-treated primate eyes are understudied. We studied NHPs with ExGl of several years duration. As expected, ExGl eyes exhibited selective reductions of the retinal nerve fiber layer that correlate with electrophysiologic measures documenting a link between morphologic and elctrophysiologic endpoints. Softening of unlasered TM in ExGl eyes compared to untreated controls was observed. The degree of TM softening was consistent, regardless of pre-mortem clinical findings including severity of IOP elevation, retinal nerve fiber layer thinning, or electrodiagnostic findings. Importantly, this softening is contrary to TM stiffening reported in glaucomatous human eyes. Furthermore, microscopic analysis of unlasered TM from eyes with ExGl demonstrated TM thinning with collapse of Schlemm's canal; and proteomic analysis confirmed downregulation of metabolic and structural proteins. These data demonstrate unexpected and compensatory changes involving the TM in the NHP model of ExGl. The data suggest that compensatory mechanisms exist in normal animals and respond to elevated IOP through softening of the meshwork to increase outflow.
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Affiliation(s)
- VijayKrishna Raghunathan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, California, 95616, United States of America
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
- The Ocular Surface Institute, Department of Basic Sciences, College of Optometry, University of Houston, Houston, Texas, 77204, United States of America
| | - J Seth Eaton
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, California, 95616, United States of America
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
| | - Brian J Christian
- Covance Laboratories, Inc., Madison, Wisconsin, 53704, United States of America
| | - Joshua T Morgan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, California, 95616, United States of America
| | - James N Ver Hoeve
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53792, United States of America
| | - Chen-Yuan Charlie Yang
- Department of Anatomy and Neurobiology, School of Medicine, Boston University, Boston, Massachusetts, 02118, United States of America
- Department of Ophthalmology, School of Medicine, Boston University, Boston, Massachusetts, 02118, United States of America
| | - Haiyan Gong
- Department of Anatomy and Neurobiology, School of Medicine, Boston University, Boston, Massachusetts, 02118, United States of America
- Department of Ophthalmology, School of Medicine, Boston University, Boston, Massachusetts, 02118, United States of America
| | - Carol A Rasmussen
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53792, United States of America
| | - Paul E Miller
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin - Madison, Madison, Wisconsin, 53706, United States of America
| | - Paul Russell
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, California, 95616, United States of America
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America
| | - T Michael Nork
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America.
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53792, United States of America.
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, California, 95616, United States of America.
- Ocular Services On Demand (OSOD), Madison, Wisconsin, 53719, United States of America.
- Department of Ophthalmology & Vision Science, School of Medicine, University of California - Davis, Sacramento, California, 95817, United States of America.
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Gospe SM, Bhatti MT, El-Dairi MA. Anatomic and visual function outcomes in paediatric idiopathic intracranial hypertension. Br J Ophthalmol 2015; 100:505-9. [PMID: 26269534 DOI: 10.1136/bjophthalmol-2015-307043] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 07/29/2015] [Indexed: 11/04/2022]
Abstract
BACKGROUND There is a paucity of literature describing risk factors for vision loss in paediatric idiopathic intracranial hypertension (IIH). We investigate the final visual function, spectral domain optical coherence tomography (SD-OCT) and enhanced depth imaging (EDI)-OCT findings in children with papilledema caused by IIH. METHODS Medical records of 31 patients with paediatric IIH (age ≤17 years) were retrospectively reviewed. Optic disc photographs on presentation and automated perimetry, SD-OCT and EDI-OCT imaging on final follow-up visit were statistically analysed to identify patient characteristics and anatomic findings associated with irreversible vision loss. RESULTS Permanent visual acuity or visual field loss developed in 19% of study eyes. Papilledema of modified Frisén grade ≥3 on presentation was highly predictive of permanent vision loss (p<0.001), while associations between pubertal status and visual function outcome failed to reach statistical significance. SD-OCT revealed optic atrophy in 13% and photoreceptor loss in 19% of eyes, with both findings highly associated with vision loss (p<0.0001). Optic disc drusen was noted in 48% of study eyes by EDI-OCT but was not found to be predictive of visual outcome. CONCLUSIONS Clinical observation of high papilledema grade on presentation is predictive of poor visual outcomes. Vision loss is associated not only with optic atrophy but also with photoreceptor damage. Interestingly, a high proportion of study eyes had optic disc drusen, which was not associated with vision loss, but can be a diagnostic challenge in distinguishing true papilledema from pseudopapilledema.
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Affiliation(s)
- Sidney M Gospe
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina USA
| | - M Tariq Bhatti
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina USA Department of Neurology, Duke University Medical Center, Durham, North Carolina, USA
| | - Mays A El-Dairi
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina USA
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Nork TM, Kim CBY, Munsey KM, Dashek RJ, Hoeve JNV. Regional choroidal blood flow and multifocal electroretinography in experimental glaucoma in rhesus macaques. Invest Ophthalmol Vis Sci 2014; 55:7786-98. [PMID: 25370515 DOI: 10.1167/iovs.14-14527] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To test a hypothesis of regional variation in the effect of experimental glaucoma on choroidal blood flow (ChBF) and retinal function. METHODS Five rhesus macaques underwent laser trabecular destruction (LTD) to induce elevated intraocular pressure (IOP). Intraocular pressures were elevated for 56 to 57 weeks. Multifocal electroretinographic (mfERG) and multifocal visual evoked cortical potential (mfVEP) testing were performed at regular intervals before and during the period of IOP elevation. At euthanasia, the IOP was manometrically controlled at 35 (experimentally glaucomatous eye) and 15 (fellow control eye) mm Hg. Fluorescent microspheres were injected into the left ventricle. Regional ChBF was determined. RESULTS All of the experimentally glaucomatous eyes exhibited supranormal first-order kernel (K1) root mean square (RMS) early portions of the mfERG waveforms and decreased amplitudes of the late waveforms. The supranormality was somewhat greater in the central macula. Second-order kernel, first slice (K2.1) RMS mfVEP response was inversely correlated (R(2) = 0.97) with axonal loss. Total ChBF was reduced in the experimentally glaucomatous eyes. The mean blood flow was 893 ± 123 and 481 ± 37 μL/min in the control and glaucomatous eyes, respectively. The ChBF showed regional variability with the greatest proportional decrement most often found in the central macula. CONCLUSIONS This is the first demonstration of globally reduced ChBF in chronic experimental glaucoma in the nonhuman primate. Both the alteration of mfERG waveform components associated with outer retinal function and the reduction in ChBF were greatest in the macula, suggesting that there may be a spatial colocalization between ChBF and some outer retinal effects in glaucoma.
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Affiliation(s)
- T Michael Nork
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Charlene B Y Kim
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Kaitlyn M Munsey
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Ryan J Dashek
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
| | - James N Ver Hoeve
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
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Park HK, Jo W, Choi HJ, Kim B, Lee G, Seo J, Cho SY, Kim CS, Choi EK, Hwang JJ, Lee JY, Yoon YH, Son WC. Usefulness of optical coherence tomography to detect central serous chorioretinopathy in monkeys. J Appl Toxicol 2014; 35:199-204. [PMID: 24677158 DOI: 10.1002/jat.3009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/09/2014] [Accepted: 02/17/2014] [Indexed: 11/07/2022]
Abstract
Many systemic drugs can induce ocular toxicity and several ocular side-effects have been identified in clinical studies. However, it is difficult to detect ocular toxicity in preclinical studies because of the lack of appropriate evaluation methods. Optical coherence tomography (OCT) is useful because it can provide real-time images throughout a study period, whereas histopathology only provides images of sacrificed animals. Using OCT alongside histopathology, attempts were made to find effective approaches for screening of drug-induced ocular toxicity in monkeys. Such approaches could be used in preclinical studies prior to human trials. Six male cynomolgus monkeys (Macaca fascicularis Raffles) were orally administered one of six candidate MAPK/ERK kinase (MEK) inhibitors. Central serous chorioretinopathy, a known side-effect of such inhibitors, was identified in four monkeys by OCT. Artifacts generated during tissue processing meant that histopathology could not detect edematous changes. Thus, OCT is a useful tool to detect ocular toxicity which cannot be detected by histopathology in preclinical studies.
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Affiliation(s)
- Hyun-Kyu Park
- Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 138736, Korea; Institute for Innovative Cancer Research, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 138736, Korea
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