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Antonelli G, Ziccardi L, Barbano L, Di Renzo A, Parisi V. Morpho-Functional Assessment of Retinal Ganglion Cells and Visual Pathways in Patients with Optic Disc Drusen: Superficial Drusen Visible Height as a Marker of Impairment. J Clin Med 2023; 12:jcm12103432. [PMID: 37240544 DOI: 10.3390/jcm12103432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The aim of this study was to assess the morpho-functional involvement of the retinal ganglion cells (RGCs) and of the visual pathways in patients with superficial (ODD-S) or deep (ODD-D) optic disc drusen. This study enrolled 17 patients with ODD (mean age of 59.10 ± 12.68 years) providing 19 eyes and 20 control subjects (mean age 58.62 ± 8.77 years) providing 20 eyes. We evaluated the following: best-corrected visual acuity, visual field mean deviation (MD), the amplitude (A) of Pattern Electroretinogram (PERG), the implicit time (IT) and A of Visual Evoked Potentials (VEPs), retinal nerve fiber layer thickness (RNFL-T) and ganglion cell thickness (GC-T). In ODD-S eyes, the drusen visible height was measured. ODD-D and ODD-S were detected in 26.3% and 73.7% of ODD eyes, respectively. Significantly (p < 0.01) reduced MD, PERG A, VEP amplitude, RNFL-T and GC-T values and significantly (p < 0.01) increased VEP IT values were found in the ODD Group as compared to the Control one. In the ODD Group, no significant correlation (p > 0.01) between PERG As and VEP ITs was found. In ODD-S, the visible height was significantly correlated (p < 0.01) with reduced MD, PERG As and RNFL-T and with increased PSD and VEP IT values. Our findings suggest that ODD might induce morpho-functional changes in RGCs and their fibers and an unrelated visual pathway dysfunction leading or not leading to visual field defects. The observed morpho-functional impairment should be ascribed to an alteration in retrograde (from the axons to the RGCs) and anterograde (from the RGCs up to the visual cortex) axoplasmic transport. In ODD-S eyes, a minimum visible height of 300 microns represented the threshold for the abnormalities, suggesting that "the higher the ODD, the worse the impairment".
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Rao A, Padhy D, Pal A, Roy AK. Visual function tests for glaucoma practice - What is relevant? Indian J Ophthalmol 2022; 70:749-758. [PMID: 35225508 PMCID: PMC9114550 DOI: 10.4103/ijo.ijo_1390_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Glaucoma represents one of the most important ocular diseases causing irreversible ganglion cell death. It is one of the most common causes of visual impairment and morbidity in the elderly population. There are various tests for measuring visual function in glaucoma. While visual field remains the undisputed method for screening, diagnosis, and monitoring disease progression, other tests have been studied for their utility in glaucoma practice. This review discusses some of the commonly used tests of visual function that can be routinely used in clinics for glaucoma management. Among the various modalities of testing visual function in glaucoma, this review highlights the tests that are most clinically relevant.
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Affiliation(s)
- Aparna Rao
- Department of Glaucoma Services, L. V. Prasad Eye Institute, Bhubaneswar, Odisha, India
| | - Debananda Padhy
- Department of Glaucoma Services, L. V. Prasad Eye Institute, Bhubaneswar, Odisha, India
| | - Anindita Pal
- Department of Glaucoma Services, L. V. Prasad Eye Institute, Bhubaneswar, Odisha, India
| | - Avik Kumar Roy
- Department of Glaucoma Services, L. V. Prasad Eye Institute, Bhubaneswar, Odisha, India
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Parisi V, Ziccardi L, Tanga L, Roberti G, Barbano L, Carnevale C, Manni G, Oddone F. Neural Conduction Along Postretinal Visual Pathways in Glaucoma. Front Aging Neurosci 2021; 13:697425. [PMID: 34408643 PMCID: PMC8365149 DOI: 10.3389/fnagi.2021.697425] [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: 04/19/2021] [Accepted: 06/07/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: This study was conducted in order to evaluate retinal ganglion cell (RCG) function and the neural conduction along the postretinal large and small axons and its correlation with retinal nerve fiber layer thickness (RNFL-T) in open-angle glaucoma (OAG) eyes. Methods: Thirty-seven OAG patients (mean age: 51.68 ± 9.83 years) with 24-2 Humphrey mean deviation (MD) between -2.5 and -20 dB and IOP <21 mmHg on pharmacological treatment (OAG group) and 20 age-matched controls (control group) were enrolled. In both groups, simultaneous pattern electroretinograms (PERG) and visual evoked potentials (VEP), in response to checks stimulating macular or extramacular areas (the check edge subtended 15' and 60' of visual arc, respectively), and RNFL-T (measured in superior, inferior, nasal, and temporal quadrants) were assessed. Results: In the OAG group, a significant (ANOVA, p < 0.01) reduction of 60' and 15' PERG P50-N95 and VEP N75-P100 amplitudes and of RNFL-T [overall (average of all quadrants) or temporal] with respect to controls was found; the values of 60' and 15' PERG P50 and VEP P100 implicit times and of retinocortical time (RCT; difference between VEP P100 and PERG P50 implicit times) were significantly (p < 0.01) increased with respect to control ones. The observed increased RCTs were significantly linearly correlated (Pearson's test, p < 0.01) with the reduced PERG amplitude and MD values, whereas no significant linear correlation (p < 0.01) with RNFL-T (overall or temporal) values was detected. Conclusions: In OAG, there is an impaired postretinal neural conduction along both large and small axons (increased 60' and 15' RCTs) that is related to RGC dysfunction, but independent from the RNFL morphology. This implies that, in OAG, the impairment of postretinal neural structures can be electrophysiologically identified and may contribute to the visual field defects, as suggested by the linear correlation between the increase of RCT and MD reduction.
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Affiliation(s)
| | | | | | | | | | | | - Gianluca Manni
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
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Oddone F, Rossetti L, Parravano M, Sbardella D, Coletta M, Ziccardi L, Roberti G, Carnevale C, Romano D, Manni G, Parisi V. Citicoline in Ophthalmological Neurodegenerative Disease: A Comprehensive Review. Pharmaceuticals (Basel) 2021; 14:281. [PMID: 33804675 PMCID: PMC8003774 DOI: 10.3390/ph14030281] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 12/12/2022] Open
Abstract
Cytidine 5'-diphosphocholine has been widely studied in systemic neurodegenerative diseases, like Alzheimer's disease, Parkinson's disease, and brain ischemia. The rationale for the use of citicoline in ophthalmological neurodegenerative diseases, including glaucoma, anterior ischemic optic neuropathy, and diabetic retinopathy, is founded on its multifactorial mechanism of action and the involvement in several metabolic pathways, including phospholipid homeostasis, mitochondrial dynamics, as well as cholinergic and dopaminergic transmission, all being involved in the complexity of the visual transmission. This narrative review is aimed at reporting both pre-clinical data regarding the involvement of citicoline in such metabolic pathways (including new insights about its role in the intracellular proteostasis through an interaction with the proteasome) and its effects on clinical psychophysical, electrophysiological, and morphological outcomes following its use in ophthalmological neurodegenerative diseases (including the results of the most recent prospective randomized clinical trials).
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Affiliation(s)
- Francesco Oddone
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Luca Rossetti
- Eye Clinic, ASST Santi Paolo e Carlo, San Paolo Hospital, University of Milan, Via Antonio di Rudinì, 8, 20142 Milan, Italy; (L.R.); (D.R.)
| | - Mariacristina Parravano
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Diego Sbardella
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy; (M.C.); (G.M.)
| | - Lucia Ziccardi
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Gloria Roberti
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Carmela Carnevale
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
| | - Dario Romano
- Eye Clinic, ASST Santi Paolo e Carlo, San Paolo Hospital, University of Milan, Via Antonio di Rudinì, 8, 20142 Milan, Italy; (L.R.); (D.R.)
| | - Gianluca Manni
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy; (M.C.); (G.M.)
| | - Vincenzo Parisi
- IRCCS-Fondazione Bietti, Via Livenza, 3, 00198 Rome, Italy; (F.O.); (D.S.); (L.Z.); (G.R.); (C.C.); (V.P.)
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The Relationship between Pupillometric Values and Visual Evoked Potential Test Results in Patients with Early Glaucoma. Optom Vis Sci 2020; 97:898-902. [PMID: 33055516 DOI: 10.1097/opx.0000000000001589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Measuring pupil diameter may provide an additional objective method to detect and monitor glaucoma. PURPOSE The purposes of this study were to evaluate whether pupillometry can be used in the assessment of glaucomatous damage and to determine whether pupillometer can be used in glaucoma screening. METHODS In this retrospective study, patients with early stages of glaucomatous optic neuropathy were tested using visual evoked potential (VEP), standard automated perimetry, and pupillometer. The VEP record was made using two consecutive check sizes (1° and 15') at 1-Hz frequency. Patients with a mean deviation of <-2 and >-6 dB were included in the study. Pupil size measurements were performed under photopic conditions at 60-, 100-, and 130-cd/m luminance levels with the OPD Scan (Nidek, Gamagori, Japan) device. RESULTS In all, 24 eyes of 24 patients (14 women and 10 men) with newly diagnosed open-angle glaucoma were included, and 30 eyes of 30 healthy subjects (15 women, 15 men) were used as controls. There was no significant difference between sexes in photopic pupil diameters in either group. Comparing the pupil diameters in different luminance levels, the diameters were significantly larger in the patient group. When age-corrected values in the glaucoma group were compared with an age-matched control group, the differences in P100 latency and amplitudes were statistically significant. There were significant correlations between photopic pupil diameters and timing of VEP waveforms. CONCLUSIONS There is a relationship between pupil diameters and VEP results in eyes with early glaucoma.
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Cho KI, Yoon D, Yu M, Peachey NS, Ferreira PA. Microglial activation in an amyotrophic lateral sclerosis-like model caused by Ranbp2 loss and nucleocytoplasmic transport impairment in retinal ganglion neurons. Cell Mol Life Sci 2019; 76:3407-3432. [PMID: 30944974 PMCID: PMC6698218 DOI: 10.1007/s00018-019-03078-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/21/2019] [Accepted: 03/18/2019] [Indexed: 12/12/2022]
Abstract
Nucleocytoplasmic transport is dysregulated in sporadic and familial amyotrophic lateral sclerosis (ALS) and retinal ganglion neurons (RGNs) are purportedly involved in ALS. The Ran-binding protein 2 (Ranbp2) controls rate-limiting steps of nucleocytoplasmic transport. Mice with Ranbp2 loss in Thy1+-motoneurons develop cardinal ALS-like motor traits, but the impairments in RGNs and the degree of dysfunctional consonance between RGNs and motoneurons caused by Ranbp2 loss are unknown. This will help to understand the role of nucleocytoplasmic transport in the differential vulnerability of neuronal cell types to ALS and to uncover non-motor endophenotypes with pathognomonic signs of ALS. Here, we ascertain Ranbp2's function and endophenotypes in RGNs of an ALS-like mouse model lacking Ranbp2 in motoneurons and RGNs. Thy1+-RGNs lacking Ranbp2 shared with motoneurons the dysregulation of nucleocytoplasmic transport. RGN abnormalities were comprised morphologically by soma hypertrophy and optic nerve axonopathy and physiologically by a delay of the visual pathway's evoked potentials. Whole-transcriptome analysis showed restricted transcriptional changes in optic nerves that were distinct from those found in sciatic nerves. Specifically, the level and nucleocytoplasmic partition of the anti-apoptotic and novel substrate of Ranbp2, Pttg1/securin, were dysregulated. Further, acetyl-CoA carboxylase 1, which modulates de novo synthesis of fatty acids and T-cell immunity, showed the highest up-regulation (35-fold). This effect was reflected by the activation of ramified CD11b+ and CD45+-microglia, increase of F4\80+-microglia and a shift from pseudopodial/lamellipodial to amoeboidal F4\80+-microglia intermingled between RGNs of naive mice. Further, there was the intracellular sequestration in RGNs of metalloproteinase-28, which regulates macrophage recruitment and polarization in inflammation. Hence, Ranbp2 genetic insults in RGNs and motoneurons trigger distinct paracrine signaling likely by the dysregulation of nucleocytoplasmic transport of neuronal-type selective substrates. Immune-modulators underpinning RGN-to-microglial signaling are regulated by Ranbp2, and this neuronal-glial system manifests endophenotypes that are likely useful in the prognosis and diagnosis of motoneuron diseases, such as ALS.
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Affiliation(s)
- Kyoung-In Cho
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA
| | - Dosuk Yoon
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Neal S Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, 44106, USA
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Paulo A Ferreira
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA.
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Parisi V, Ziccardi L, Sadun F, De Negri AM, La Morgia C, Barbano L, Carelli V, Barboni P. Functional Changes of Retinal Ganglion Cells and Visual Pathways in Patients with Chronic Leber’s Hereditary Optic Neuropathy during One Year of Follow-up. Ophthalmology 2019; 126:1033-1044. [DOI: 10.1016/j.ophtha.2019.02.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/28/2019] [Accepted: 02/15/2019] [Indexed: 10/27/2022] Open
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Lek JJ, Nguyen BN, McKendrick AM, Vingrys AJ. An Electrophysiological Comparison of Contrast Response Functions in Younger and Older Adults, and Those With Glaucoma. Invest Ophthalmol Vis Sci 2019; 60:442-450. [PMID: 30703209 DOI: 10.1167/iovs.17-23522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Aging and glaucoma both result in contrast processing deficits. However, it is unclear the extent to which these functional deficits arise from retinal or post-retinal neuronal changes. This study aims to disentangle the effects of healthy human aging and glaucoma on retinal and post-retinal contrast processing using visual electrophysiology. Methods Steady-state pattern electroretinograms (PERG) and pattern visual evoked potentials (PVEP) were simultaneously recorded across a range of contrasts (0%, 4%, 9%, 18%, 39%, 73%, 97%; 0.8° diameter checks, 31° diameter checkerboard) in 13 glaucoma patients (67 ± 6 years), 15 older (63 ± 8 years) and 14 younger adults (27 ± 3 years). PERG and PVEP contrast response functions were fit with a linear and saturating hyperbolic model, respectively. PERG and PVEP magnitude, timing (phase), and model fit parameters (slope, semi-saturation constant) were compared between groups. Results PERG responses were reduced and delayed in older adults relative to younger adults, and further reduced and delayed in glaucoma patients across all contrasts. PVEP signals were also reduced and delayed in glaucoma patients, relative to age-similar (older) controls. However, despite having reduced PERG magnitudes, older adults did not demonstrate reduced PVEP magnitudes. Conclusions Older adults with healthy vision demonstrate reduced magnitude and delayed timing in the PERG that is not reflected in the PVEP. In contrast, glaucoma produces functional deficits in both PERG and PVEP contrast response functions. Our results suggest that glaucomatous effects on contrast processing are not a simple extension of those that arise as part of the aging process.
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Affiliation(s)
- Jia Jia Lek
- Department of Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Bao N Nguyen
- Department of Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Allison M McKendrick
- Department of Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
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Parisi V, Oddone F, Ziccardi L, Roberti G, Coppola G, Manni G. Citicoline and Retinal Ganglion Cells: Effects on Morphology and Function. Curr Neuropharmacol 2018; 16:919-932. [PMID: 28676014 PMCID: PMC6120106 DOI: 10.2174/1570159x15666170703111729] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/07/2017] [Accepted: 06/22/2017] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Retinal ganglion cells (RGCs) are the nervous retinal elements which connect the visual receptors to the brain forming the nervous visual system. Functional and/or morphological involvement of RGCs occurs in several ocular and neurological disorders and therefore these cells are targeted in neuroprotective strategies. Cytidine 5-diphosphocholine or Citicoline is an endogenous compound that acts in the biosynthesis of phospholipids of cell membranes and increases neurotransmitters' levels in the Central Nervous System. Experimental studies suggested the neuromodulator effect and the protective role of Citicoline on RGCs. This review aims to present evidence of the effects of Citicoline in experimental models of RGCs degeneration and in human neurodegenerative disorders involving RGCs. METHODS All published papers containing experimental or clinical studies about the effects of Citicoline on RGCs morphology and function were reviewed. RESULTS In rodent retinal cultures and animal models, Citicoline induces antiapoptotic effects, increases the dopamine retinal level, and counteracts retinal nerve fibers layer thinning. Human studies in neurodegenerative visual pathologies such as glaucoma or non-arteritic ischemic neuropathy showed a reduction of the RGCs impairment after Citicoline administration. By reducing the RGCs' dysfunction, a better neural conduction along the post-retinal visual pathways with an improvement of the visual field defects was observed. CONCLUSION Citicoline, with a solid history of experimental and clinical studies, could be considered a very promising molecule for neuroprotective strategies in those pathologies (i.e. Glaucoma) in which morpho-functional changes of RGCc occurs.
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Affiliation(s)
- Vincenzo Parisi
- IRCCS-Fondazione GB Bietti, Via Livenza, 3, 00198 Rome, Italy
| | | | - Lucia Ziccardi
- IRCCS-Fondazione GB Bietti, Via Livenza, 3, 00198 Rome, Italy
| | - Gloria Roberti
- IRCCS-Fondazione GB Bietti, Via Livenza, 3, 00198 Rome, Italy
| | | | - Gianluca Manni
- IRCCS-Fondazione GB Bietti, Via Livenza, 3, 00198 Rome, Italy.,DSCMT, Università di Roma Tor Vergata, Viale Oxford 81, 00133 Rome, Italy
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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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Park HH, Chun YS. Relationship between Binocular Visual Function and Quality of Life in Bilateral Normal Tension Glaucoma Patients. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2017. [DOI: 10.3341/jkos.2017.58.2.171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Hong Hyun Park
- Department of Ophthalmology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Yeoun Sook Chun
- Department of Ophthalmology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
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Grieb P, Jünemann A, Rekas M, Rejdak R. Citicoline: A Food Beneficial for Patients Suffering from or Threated with Glaucoma. Front Aging Neurosci 2016; 8:73. [PMID: 27092075 PMCID: PMC4824764 DOI: 10.3389/fnagi.2016.00073] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/28/2016] [Indexed: 12/13/2022] Open
Abstract
Oral form of citicoline, a nootropic and neuroprotective drug in use for almost five decades, recently was pronounced a food supplement in both USA and EU. The idea of adding citicoline to topical treatment of primary open angle glaucoma (POAG) aimed at decreasing intraocular pressure (IOP) appeared as a logical consequence of accepting neurodegenerative character of this disease. Experimental data, and also few clinical studies indicate that this substance has potential to counteract some important pathological mechanisms which seem to contribute to POAG initiation and progression, such as excitotoxicity and oxidative stress.
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Affiliation(s)
- Pawel Grieb
- Department of Experimental Pharmacology, Mossakowski Medical Research Centre, Polish Academy of Sciences Warsaw, Poland
| | - Anselm Jünemann
- Department of Ophthalmology, University of Rostock Rostock, Germany
| | - Marek Rekas
- Department of Ophthalmology, Military Institute of Medicine Warsaw, Poland
| | - Robert Rejdak
- Department of Experimental Pharmacology, Mossakowski Medical Research Centre, Polish Academy of SciencesWarsaw, Poland; Department of General Ophthalmology, Medical University of LublinLublin, Poland
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Yucel YH, Gupta N. A framework to explore the visual brain in glaucoma with lessons from models and man. Exp Eye Res 2015; 141:171-8. [DOI: 10.1016/j.exer.2015.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 06/29/2015] [Accepted: 07/09/2015] [Indexed: 01/13/2023]
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Experimental and clinical evidence of neuroprotection by nerve growth factor eye drops: Implications for glaucoma. Proc Natl Acad Sci U S A 2015; 106:13469-74. [PMID: 19805021 DOI: 10.1073/pnas.0906678106] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Elevated intraocular pressure (IOP) in glaucoma causes loss of retinal ganglion cells (RGCs) and damage to the optic nerve. Although IOP is controlled pharmacologically, no treatment is available to restore retinal and optic nerve function. We evaluated the effects of NGF eye drops in a rat model of glaucoma. We also treated 3 patients with progressive visual field defects despite IOP control. Glaucoma was induced in rats through injection of hypertonic saline into the episcleral vein. Initially, 2 doses of NGF (100 and 200 mug/mL) were tested on 24 rats, and the higher dose was found to be more effective. Glaucoma was then induced in an additional 36 rats: half untreated and half treated with 200 mug/mL NGF QID for 7 weeks. Apoptosis/survival of RGCs was evaluated by histological, biochemical, and molecular analysis. Three patients with advanced glaucoma underwent psychofunctional and electrofunctional tests at baseline, after 3 months of NGF eye drops, and after 3 months of follow-up. Seven weeks of elevated IOP caused RGC degeneration resulting in 40% cell death. Significantly less RGC loss was observed with NGF treatment (2,530 +/- 121 vs. 1,850 +/- 156 RGCs/mm(2)) associated with inhibition of cell death by apoptosis. Patients treated with NGF demonstrated long lasting improvements in visual field, optic nerve function, contrast sensitivity, and visual acuity. NGF exerted neuroprotective effects, inhibiting apoptosis of RGCs in animals with glaucoma. In 3 patients with advanced glaucoma, treatment with topical NGF improved all parameters of visual function. These results may open therapeutic perspectives for glaucoma and other neurodegenerative diseases.
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Nguyen BN, Lek JJ, Vingrys AJ, McKendrick AM. Clinical impact of migraine for the management of glaucoma patients. Prog Retin Eye Res 2015; 51:107-24. [PMID: 26232725 DOI: 10.1016/j.preteyeres.2015.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/23/2015] [Accepted: 07/27/2015] [Indexed: 12/19/2022]
Abstract
Migraine is a common and debilitating primary headache disorder that affects 10-15% of the general population, particularly people of working age. Migraine is relevant to providers of clinical eye-care because migraine attacks are associated with a range of visual sensory symptoms, and because of growing evidence that the results of standard tests of visual function necessary for the diagnosis and monitoring of glaucoma (visual fields, electrophysiology, ocular imaging) can be abnormal due to migraine. These abnormalities are measureable in-between migraine events (the interictal period), despite patients being asymptomatic and otherwise healthy. This picture is further complicated by epidemiological data that suggests an increased prevalence of migraine in patients with glaucoma, particularly in patients with normal tension glaucoma. We discuss how migraine, as a co-morbidity, can confound the results and interpretation of clinical tests that form part of contemporary glaucoma evaluation, and provide practical evidence-based recommendations for the clinical testing and management of patients with migraine who attend eye-care settings.
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Affiliation(s)
- Bao N Nguyen
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
| | - Jia Jia Lek
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Allison M McKendrick
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
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Parisi V, Centofanti M, Ziccardi L, Tanga L, Michelessi M, Roberti G, Manni G. Treatment with citicoline eye drops enhances retinal function and neural conduction along the visual pathways in open angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2015; 253:1327-40. [PMID: 26004075 DOI: 10.1007/s00417-015-3044-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/07/2015] [Accepted: 04/29/2015] [Indexed: 10/23/2022] Open
Abstract
PURPOSE To evaluate the retinal function and the neural conduction along the visual pathways after treatment with citicoline eye drops in patients with open angle glaucoma (OAG). METHODS Fifty-six OAG patients (mean age 52.4 ± 4.72 years, IOP <18 mmHg with beta-blocker monotherapy only) were enrolled. Of these, 47 eyes completed the study: 24 OAG eyes were treated with topical citicoline (OMK1®, Omikron Italia, 3 drops/day) (GC eyes) over a 4-month period (month 4) followed by a 2-month period of citicoline wash-out (month 6), and another 23 OAG eyes were only treated with beta-blocker monotherapy (GP eyes). In GC and GP eyes, pattern electroretinogram (PERG) and visual evoked potentials (VEP) were assessed at baseline and at months 4 and 6 in both groups. RESULTS At baseline, similar (ANOVA, p > 0.01) PERG and VEP values in GC and GP eyes were observed. After treatment with topical citicoline, a significant (p < 0.01) increase of PERG P50-N95 and VEP N75-P100 amplitudes, and a significant (p < 0.01) shortening of VEP P100 implicit times were found. In GC eyes, the shortening of VEP P100 implicit times was correlated significantly (p < 0.01) with the increase of PERG P50-N95 amplitudes. After a 2-month period of topical Citicoline wash-out, PERG and VEP values were similar (p > 0.01) to baseline ones. GP eyes showed not significant changes of PERG and VEP values during the entire follow-up. CONCLUSIONS Topical treatment with citicoline in OAG eyes induces an enhancement of the retinal bioelectrical responses (increase of PERG amplitude) with a consequent improvement of the bioelectrical activity of the visual cortex (shortening and increase of VEP implicit time and amplitude, respectively).
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Affiliation(s)
- Vincenzo Parisi
- "G.B. Bietti" Foundation for Study and Research in Ophthalmology - IRCCS, Via Livenza 3, 000198, Rome, Italy
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Effects of coenzyme Q10 in conjunction with vitamin E on retinal-evoked and cortical-evoked responses in patients with open-angle glaucoma. J Glaucoma 2015; 23:391-404. [PMID: 25079307 DOI: 10.1097/ijg.0b013e318279b836] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate pattern-evoked retinal and cortical responses [pattern electroretinogram (PERG) and visual-evoked potential (VEP), respectively] after treatment with coenzyme Q10 in conjunction with vitamin E in open-angle glaucoma (OAG) patients. METHODS Forty-three OAG patients (mean age, 52.5±5.29 y; intraocular pressure <18 mm Hg with β-blocker monoterapy only) were enrolled. At baseline and after 6 and 12 months, simultaneous recordings of PERG and VEPs were obtained from 22 OAG patients who underwent treatment consisting of coenzyme Q10 and vitamin E (Coqun, 2 drops/d) in addition to β-blocker monoterapy (GC group), and from 21 OAG patients who were only treated with β-blockers (GP group). RESULTS At baseline, intraocular pressure, PERG, and VEP parameters were similar in both GC and GP groups (analysis of variance, P>0.05). After 6 and 12 months, PERG and VEP response parameters of GP patients were unchanged when compared to baseline. In GC patients, PERG P50 and VEP P100 implicit times were decreased, whereas PERG P50-N95 and VEP N75-P100 amplitudes were increased (P<0.01) when compared to baseline. In the GC group, the differences in implicit times and amplitudes with respect to baseline were significantly larger (P<0.01) than those recorded in the GP group. The improvement (12 mo minus baseline) of VEP implicit time was significantly correlated with the changes of PERG P50-N95 amplitude (r=-0.66171, P=0.0008) and P50 implicit time (r=0.68364, P=0.00045) over a period of 12 months. CONCLUSIONS Coenzyme Q10 associated with vitamin E administration in OAG shows a beneficial effect on the inner retinal function (PERG improvement) with consequent enhancement of the visual cortical responses (VEP improvement).
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Kothari R, Bokariya P, Singh R, Singh S, Narang P. Correlation of pattern reversal visual evoked potential parameters with the pattern standard deviation in primary open angle glaucoma. Int J Ophthalmol 2014; 7:326-9. [PMID: 24790879 DOI: 10.3980/j.issn.2222-3959.2014.02.24] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 08/22/2013] [Indexed: 11/02/2022] Open
Abstract
AIM To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation (PSD) of Humphrey visual field could be associated with visual evoked potential (VEP) parameters of patients having primary open angle glaucoma (POAG). METHODS Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential (PRVEP) were assessed in 100 patients with POAG. The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated (full field) and displayed on VEP monitor (colour 14″) by an electronic pattern regenerator inbuilt in an evoked potential recorder (RMS EMG EP MARK II). RESULTS The results of our study indicate that there is a highly significant (P<0.001) negative correlation of P100 amplitude and a statistically significant (P<0.05) positive correlation of N70 latency, P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student's t-test. CONCLUSION Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values. Conversely, as PSD increases the magnitude of VEP excursions were found to be diminished.
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Affiliation(s)
- Ruchi Kothari
- Department of Physiology, MGIMS, Sevagram, Wardha, Maharashtra 442102, India
| | - Pradeep Bokariya
- Department of Anatomy, MGIMS, Sevagram, Wardha, Maharashtra 442102, India
| | - Ramji Singh
- Department of Physiology, AIIMS, Patna, Bihar 801105, India
| | - Smita Singh
- Department of Ophthalmology, MGIMS, Sevagram,Wardha, Maharashtra 442102, India
| | - Purvasha Narang
- Department of Ophthalmology, MGIMS, Sevagram,Wardha, Maharashtra 442102, India
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Huseyinoglu N, Ekinci M, Ozben S, Buyukuysal C. Relationship between Structural and Functional Assessment of the Visual System in Mildly Disabled Relapsing-Remitting Multiple Sclerosis Patients. Neuroophthalmology 2014; 38:1-7. [PMID: 27928266 DOI: 10.3109/01658107.2013.855242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 10/01/2013] [Indexed: 01/21/2023] Open
Abstract
Studies that explored the anterior visual pathway in the patients with multiple sclerosis (MS) have demonstrated contradictory results about the correlation between structural and functional status of optic nerve and retina. We aimed to investigate the functional and structural findings in our cohort of mildly disabled relapsing-remitting MS patients. A total of 134 eyes (80 eyes of the patients with MS and 54 eyes of the control group) were investigated. Eyes of MS patients were divided into two groups-as eyes with history of optic neuritis (ON group) and without history of optic neuritis (NON group). Ophthalmological investigation including visual evoked potentials, standard automated perimetry, and optical coherence tomography were performed for all participants. Retinal and macular thicknesses were significantly decreased in ON and NON groups compared with controls. Also, visual evoked potential latencies and visual field loss were worse in the both MS groups compared with control group. We did not find any correlation between visual evoked potentials and retinal or macular thickness values but visual field parameters were correlated between retinal and macular layer loss in the NON group. According to our results and some previous studies, although both functional and structural changes were detected in patients with MS, functional status markers do not always show parallelism (or synchrony) with structural changes, especially in eyes with history of optic neuritis.
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Affiliation(s)
| | - Metin Ekinci
- Department of Ophthalmology, Kafkas University Medical Faculty Kars Turkey
| | - Serkan Ozben
- Department of Neurology, Kafkas University Medical Faculty Kars Turkey
| | - Cagatay Buyukuysal
- Department of Biostatistics, Bülent Ecevit University Medical Faculty Zonguldak Turkey
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Petrović M, Jovanović P, Trenkić Božinović M, Bojović L, Jolić M. POTENCIJALNA ULOGA VIZUELNO EVOCIRANIH POTENCIJALA I "PATTERN" ELEKTRORETINOGRAFIJE U DIJAGNOZI PRIMARNOG GLAUKOMA OTVORENOG UGLA. ACTA MEDICA MEDIANAE 2012. [DOI: 10.5633/amm.2012.0403s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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21
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Significance of Visual Evoked Potentials in the Assessment of Visual Field Defects in Primary Open-Angle Glaucoma: A Review. NEUROSCIENCE JOURNAL 2012; 2013:418320. [PMID: 26317091 PMCID: PMC4475581 DOI: 10.1155/2013/418320] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 10/31/2012] [Accepted: 11/12/2012] [Indexed: 11/17/2022]
Abstract
Visual evoked potentials is an important visual electrophysiological tool which has been used for the evaluation of visual field defects in primary open-angle glaucoma and is an appropriate objective measure of optic nerve function. Significant correlations between the magnitude of the VEP parameters and MD of Humphrey static perimetry suggest that the impaired visual cortical responses observed in glaucoma patients can be revealed by both electrophysiological and psychophysical methods. In addition, the severity of global glaucomatous damage evidenced by reduction in MD could depend on the delay in neural conduction from retina to the visual cortex as revealed by the significant correlation between VEP latencies and MD which also supports the validity of the VEP testing in progression of glaucoma.
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Kanjee R, Yücel YH, Steinbach MJ, González EG, Gupta N. Delayed saccadic eye movements in glaucoma. Eye Brain 2012; 4:63-68. [PMID: 28539782 DOI: 10.2147/eb.s38467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
PURPOSE To determine whether saccadic eye movements are altered in glaucoma patients. PATIENTS AND METHODS Sixteen patients with glaucoma and 21 control subjects were prospectively studied. Patients participated in a pro-saccade step task. Saccades were recorded using a noninvasive infrared oculometric device with head-mounted target projection. Medians of saccade reaction time, duration, amplitude, and peak velocity; frequency of express saccades; and percentage of trials with direction error were recorded. t-tests were used to compare the glaucoma and age-matched control groups. A correlation analysis of saccade parameters with visual field loss was also performed. RESULTS Median saccade reaction times were significantly prolonged in glaucoma patients compared with controls (220.9 ± 49.02 ms vs 192.1 ± 31.24 ms; t-test: P = 0.036). Median duration, median amplitude, and median peak velocity of saccades did not show significant differences between glaucoma and control groups (P > 0.05). Frequency of express saccades was significantly decreased in glaucoma patients compared with controls (1.75 ± 2.32 vs 7.0 ± 6.99; t-test: P = 0.007). Saccade parameters in glaucoma patients showed no significant correlation with visual field loss. CONCLUSION Saccadic eye movements are significantly delayed in patients with early, moderate, or advanced glaucoma. Determination of median saccade reaction time may offer a novel functional test to quantify visual function in glaucoma patients. Further studies are needed to determine pathological processes implicated in delayed initiation of saccades, and to assess whether alteration of saccades affects daily activities in glaucoma patients.
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Affiliation(s)
- Raageen Kanjee
- Ophthalmology and Vision Sciences, Laboratory Medicine and Pathobiology, St Michael's Hospital, University of Toronto
| | - Yeni H Yücel
- Ophthalmology and Vision Sciences, Laboratory Medicine and Pathobiology, St Michael's Hospital, University of Toronto.,Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital
| | - Martin J Steinbach
- Toronto Western Hospital, University Health Network.,Centre for Vision Research, York University
| | - Esther G González
- Toronto Western Hospital, University Health Network.,Centre for Vision Research, York University
| | - Neeru Gupta
- Ophthalmology and Vision Sciences, Laboratory Medicine and Pathobiology, St Michael's Hospital, University of Toronto.,Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital.,Glaucoma and Nerve Protection Unit, St Michael's Hospital, Toronto, ON, Canada
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CHAN KEVINC, CHEUNG MATTHEWM, WU EDX. IN VIVOMULTIPARAMETRIC MAGNETIC RESONANCE IMAGING AND SPECTROSCOPY OF RODENT VISUAL SYSTEM. J Integr Neurosci 2010; 9:477-508. [DOI: 10.1142/s0219635210002524] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 11/04/2010] [Indexed: 01/27/2023] Open
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Versteeg VL, Marchand Y, Mazerolle EL, D'Arcy RCN. Profiling brain function: spatiotemporal characterization of normal and abnormal visual activation. J Neurosci Methods 2010; 190:95-105. [PMID: 20416337 DOI: 10.1016/j.jneumeth.2010.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 04/11/2010] [Accepted: 04/14/2010] [Indexed: 11/29/2022]
Abstract
OBJECTIVE In clinical neuroscience, the utility of evoked and event-related potentials (EPs and ERPs) resides in the temporal information they provide. However, it is largely unknown whether valuable diagnostic information resides within the corresponding spatial patterns. To determine this, the first step involves testing whether "normal" versus "abnormal" EPs/ERPs can be differentiated based on spatial patterns. In the current study, we present a method that characterizes similarities across individual source maps, called the profile algorithm. The profile algorithm was evaluated in terms of its ability to detect spatial activation differences in myopic individuals with corrected and uncorrected vision. This experiment represents a critical test of the method before applying it to the assessment of perceptual/cognitive functions. METHODS Visual-evoked potentials (VEPs) were recorded from healthy subjects using checkerboard stimulation. The N75 and P100 were examined in individuals with corrected (20/20) and uncorrected vision (20/40 or worse). RESULTS AND CONCLUSION N75 and P100 amplitudes and latencies were modulated by vision condition. The profile algorithm differentiated successfully between corrected and uncorrected vision. Its discriminatory power outperformed a more traditional method based on ERP peak amplitude. Subsequent correlations revealed significant relationships between visual impairment and both the components and the spatial activation. Overall, the findings suggested that VEP spatial patterns were sensitive to manipulations of visual acuity. SIGNIFICANCE The findings demonstrate that EP/ERP spatial activation can be evaluated at the individual level and compared against normative data. Ultimately, the method may provide a valuable tool for assessing individual spatial activation changes in perceptual/cognitive functions.
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Affiliation(s)
- Vanessa L Versteeg
- National Research Council Canada, Institute for Biodiagnostics (Atlantic), Halifax, NS, Canada
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Vizzeri G, Tafreshi A, Weinreb RN, Bowd C. Effect of operator and optical defocus on the variability of pattern electroretinogram optimized for glaucoma detection (PERGLA). J Glaucoma 2010; 19:77-82. [PMID: 19373105 PMCID: PMC2824045 DOI: 10.1097/ijg.0b013e31819f934e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the effect of operator and optical defocus on the variability of pattern electroretinogram optimized for glaucoma detection (PERGLA). METHODS Two different operators obtained 2 PERGLA recordings each from 10 healthy participants (5 women, mean age 32.1+/-10.3 y). In addition, one of the operators obtained recordings in which corrective lenses of various diopters (+/-0.5, +/-1, +/-2, and +/-3) were used to generate optical defocus in both eyes. The effect of operator on PERGLA amplitude and phase variability was determined using a single nested variance components' analysis model and by using Bland-Altman plots. One-way analysis of variance (ANOVA) was used to determine the effect of optical defocus on amplitude and phase. RESULTS Differences in measurements between operators accounted for approximately 26.6% and 18.2% of the total variance for amplitude and phase, respectively. Results were confirmed by the use of Bland-Altman plots. ANOVA identified a significant effect of defocus on mean amplitude (F=2.65, P=0.01), but not phase (F=1.02, P=0.42). CONCLUSIONS Measurements obtained by different operators can result in significant differences in PERGLA amplitude. In addition, although optical defocus leads to a decrease in PERGLA amplitude by reducing visual acuity, this can be avoided by obtaining J1 or better vision before testing.
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Affiliation(s)
- Gianmarco Vizzeri
- Department of Ophthalmology, Hamilton Glaucoma Center, University of California, San Diego, La Jolla, CA 92037-0946, USA
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Repeatability of pattern electroretinogram measurements using a new paradigm optimized for glaucoma detection. J Glaucoma 2009; 18:437-42. [PMID: 19680050 DOI: 10.1097/ijg.0b013e31818c6f44] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine the within-trial and between-trial repeatability of pattern electroretinogram (PERG) measurements in healthy and patient eyes, using a new clinical instrument, the PERGLA. STUDY DESIGN In all, 70 eyes of 35 healthy individuals (intraocular pressure <22 mm Hg, healthy optic disc by stereophotograph assessment, standard visual fields within normal limits) and 90 eyes of 45 clinic patients (ocular hypertensive, glaucomatous optic neuropathy by stereophotograph assessment and/or repeatable abnormal visual fields) enrolled in the University of California, San Diego Diagnostic Innovations in Glaucoma Study (DIGS) were evaluated. Average mean deviation of patient eyes on standard automated perimetry was -1.81 dB (SD=2.61). METHODS The PERG was recorded using the PERGLA paradigm from both eyes simultaneously twice (ie, 2 trials) by a single operator with electrodes being removed and reattached between recordings. Repeatability of PERG amplitude (microV) and phase (pi rad) between 2 runs within a single trial (within-trial condition) was compared with repeatability between 2 trials (ie, after electrode replacement, between-trial condition) by calculating the coefficients of variability (CVs) and the intraclass correlation coefficients (ICCs) and displaying Bland-Altman plots. RESULTS For healthy eyes, amplitude CVs (SD) were 11.5% (11.5) and 9.9% (0.79) for within-trial and between-trial conditions, respectively. ICCs were 0.91 and 0.85. Phase CVs were 1.3% (1.5) (within-trials) and 1.5% (1.4) (between-trials) and ICCs were 0.85 and 0.88. For patient eyes, amplitude CVs (SD) were 12.2% (10.1) and 11.2% (7.5) for within-trial and between-trial conditions, respectively. ICCs were 0.92 and 0.89. Phase CVs were 2.2% (2.2) (within-trials) and 2.4% (2.2) (between-trials) and ICCs were 0.82 and 0.83. Bland-Altman plots indicated good agreement between the repeated recordings and were similar within-trials and between-trials for healthy and patient eyes. CONCLUSIONS Repeatability of PERGLA recordings is good and is similar within-trials and between-trials for both healthy and patient eyes suggesting this technique is promising for monitoring change over time.
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Color Doppler imaging and pattern visual evoked potential in normal tension glaucoma and hypertension glaucoma. Doc Ophthalmol 2009; 119:171-80. [DOI: 10.1007/s10633-009-9192-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 08/24/2009] [Indexed: 11/25/2022]
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28
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Sposato V, Parisi V, Manni L, Antonucci MT, Di Fausto V, Sornelli F, Aloe L. Glaucoma alters the expression of NGF and NGF receptors in visual cortex and geniculate nucleus of rats: effect of eye NGF application. Vision Res 2008; 49:54-63. [PMID: 18938194 DOI: 10.1016/j.visres.2008.09.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/25/2008] [Accepted: 09/26/2008] [Indexed: 10/21/2022]
Abstract
We investigated the effect of glaucoma (GL) on nerve growth factor (NGF) presence in two brain visual areas. Rats with elevated intraocular pressure (EIOP), induced by hypertonic saline injection in the episcleral vein, were treated with eye topical application of saline or NGF. Rats were subsequently sacrificed, and brain tissues were used for immunohistochemical, biochemical, and molecular analyses. We found that GL alters the basal level of NGF and NGF receptors in brain visual centers and that NGF eye application normalized these deficits. These findings demonstrate that the reduced presence of NGF can arise due to degenerative events in retinal and brain visual areas.
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Affiliation(s)
- Valentina Sposato
- Institute of Neurobiology and Molecular Medicine, Section of Neurobiology, National Research Council (CNR), Via del Fosso di Fiorano, 64/65, I-00143 Rome, Italy
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Chan KC, So KF, Wu EX. Proton magnetic resonance spectroscopy revealed choline reduction in the visual cortex in an experimental model of chronic glaucoma. Exp Eye Res 2008; 88:65-70. [PMID: 18992243 DOI: 10.1016/j.exer.2008.10.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 09/28/2008] [Accepted: 10/02/2008] [Indexed: 11/20/2022]
Abstract
Glaucoma is a neurodegenerative disease of the visual system. While elevated intraocular pressure is considered to be a major risk factor, the primary cause and pathogenesis of this disease are still unclear. This study aims to employ in vivo proton magnetic resonance spectroscopy ((1)H MRS) to evaluate the metabolic changes in the visual cortex in a rat model of chronic glaucoma. Five Sprague-Dawley female rats were prepared to induce ocular hypertension unilaterally in the right eye by photocoagulating the episcleral and limbal veins using an argon laser. Single voxel (1)H MRS was performed on each side of the visual cortex 6 weeks after laser treatment. Relative to the creatine level, the choline level was found to be significantly lower in the left glaucomatous visual cortex than the right control visual cortex in all animals. In addition, a marginally significant increase in glutamate level was observed in the glaucomatous visual cortex. No apparent difference was observed between contralateral sides of the visual cortex in T1-weighted or T2-weighted imaging. The results of this study showed that glaucoma is accompanied with alterations in the metabolism of choline-containing compounds in the visual cortex contralateral to the glaucomatous rat eye. These potentially associated the pathophysiological mechanisms of glaucoma with the dysfunction of the cholinergic system in the visual pathway. (1)H MRS is a potential tool for studying the metabolic changes in glaucoma in vivo in normally appearing brain structures, and may possess direct clinical applications for humans. Measurement of the Cho:Cr reduction in the visual cortex may be a noninvasive biomarker for this disease.
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Affiliation(s)
- Kevin C Chan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong
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Parisi V, Coppola G, Centofanti M, Oddone F, Angrisani AM, Ziccardi L, Ricci B, Quaranta L, Manni G. Evidence of the neuroprotective role of citicoline in glaucoma patients. PROGRESS IN BRAIN RESEARCH 2008; 173:541-54. [PMID: 18929133 DOI: 10.1016/s0079-6123(08)01137-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The glaucomatous disease is currently considered a disease involving ocular and visual brain structures. This new approach to glaucoma introduces the possibility of inducing an improvement by means of a pharmacological approach similar to that used in different degenerative brain disorders. In line with this hypothesis, we studied the effects of oral (1600 mg/die, Cebrolux, Tubilux Pharma, Pomezia, Rome, Italy) or intramuscular (1000 mg/die, Cebroton, Tubilux Pharma) cytidine-5'-diphosphocholine (citicoline) treatment on retinal function and neural conduction in the visual pathways of glaucoma patients with moderate visual defects. Improvement of retinal function (objectively evaluated by pattern electroretinogram recordings) and of neural conduction along visual pathways (objectively evaluated by visual evoked potential recordings) were observed in glaucoma patients after two 60-day periods of oral or intramuscular treatment with citicoline. However, partial regression of this improvement was detected after two 120-day periods of washout. This suggests that the beneficial effects observed are in part treatment-dependent. The extension of citicoline treatment up to a period of 8 years lead to the stabilization or improvement of the glaucomatous visual dysfunction. These results suggest potential neuroprotective effects of citicoline in the glaucomatous disease.
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Rodarte C, Hood DC, Yang EB, Grippo T, Greenstein VC, Liebmann JM, Ritch R. The effects of glaucoma on the latency of the multifocal visual evoked potential. Br J Ophthalmol 2006; 90:1132-6. [PMID: 16707520 PMCID: PMC1857385 DOI: 10.1136/bjo.2006.095158] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To determine the effect of glaucomatous damage on the latency of the multifocal visual evoked potential (mfVEP). METHODS Monocular mfVEPs were recorded from a glaucoma group (n = 50) defined by a glaucomatous disc and an abnormal visual field and a control group (n = 47). 25 patients were characterised as normal tension glaucoma (NTG) and 25 as high tension glaucoma (HTG). Monocular and interocular latency analyses of the more affected eye were obtained using custom software. RESULTS On interocular analysis, both the HTG and NTG groups showed a statistically significant increase in mean mfVEP latency with average relative latencies and percentage of points with significant delays of 1.7 ms and 10.3% (HTG) and 1.3 ms and 8.2% (NTG) compared to -0.3 ms and 2.7% (controls). On monocular analysis, only the HTG group showed a significant increase in latency with measures of 5.7 ms and 14.6% (HTG) compared to 3.2 ms and 10.6% (NTG) and 2.1 ms and 9.6% (controls). Using the 95th percentile of a normative group as the cut off, the sensitivity ranged from 20% to 38% and the specificity from 87% to 100% with the interocular analysis providing the best discrimination, CONCLUSION Although up to 40% of patients showed delays in the mfVEP latency, these delays were modest, on average a few milliseconds. These results differ markedly from those of a recent conventional VEP study, which reported 100% sensitivity, 100% specificity, and an average delay that exceeded 25 ms.
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Affiliation(s)
- C Rodarte
- Department of Psychology, 405 Schermerhorn, Columbia University, New York, NY 10027, USA
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Abstract
AIM To investigate depth perception in glaucoma suspects compared to glaucoma patients and controls. METHODS Glaucoma suspects (n = 16), patients (n = 18), and normal age matched controls (n = 19) aged 40-65 years were prospectively evaluated for depth perception deficits using the Frisby test. Stereoacuity was measured by stereothreshold in seconds of arc for each group. RESULTS Glaucoma suspects showed significantly increased mean stereothreshold compared to age matched normals (144.1 (SE 35.2) v 26.6 (3.7) seconds of arc; p = 0.0004). The mean stereothreshold in glaucoma patients was also increased compared to age matched normals 148.1 (33.8) v 26.6 (3.7) seconds of arc; p = 0.0004). CONCLUSIONS Glaucoma suspects show depth perception deficits. The impaired stereovision in glaucoma suspects suggests that binocular interactions can be disrupted in the presence of normal visual fields by standard achromatic automated perimetry.
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Affiliation(s)
- N Gupta
- Glaucoma and Nerve Protection Unit, Department of Ophthalmology and Vision Sciences, University of Toronto, St Michael's Hospital, Toronto, Ontario, Canada, M5B 1W8.
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Parisi V. Electrophysiological assessment of glaucomatous visual dysfunction during treatment with cytidine-5'-diphosphocholine (citicoline): a study of 8 years of follow-up. Doc Ophthalmol 2006; 110:91-102. [PMID: 16249960 DOI: 10.1007/s10633-005-7348-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study we assessed, by simultaneous recordings of visual evoked potentials (VEPs) and pattern-electroretinograms (PERGs), the effects cytidine-5'-diphosphocholine (citicoline) on retinal function and/or visual cortical responses in glaucoma patients. Thirty glaucoma patients were randomly divided into two age-matched groups: patients in group GC (15 patients) were treated with citicoline (1,000 mg/die intramuscularly) for 2 months; patients in group GP (15 patients) were treated with placebo for 2 months. After 4 months of wash-out (month 6), GC patients underwent a further 2-month period of citicoline treatment (months 7-8) followed by another 4-month period of wash-out (months 9-12). In GP patients the wash-out was extended for a further 6 months (months 7-12). During the following 13-96 months, GC patients received additional 2-month periods of treatment with citicoline (each period followed by 4 months of wash-out) for a total of 16 periods in 8 years. GP patients were also examined at months 24, 26, 48, 60, 72, 84 and 96. In GC patients the first two treatments with citicoline induced a significant (p <0.01) improvement of VEP and PERG parameters with respect to pre-treatment conditions. VEPs and PERGs recorded in GC patients after the first wash-out revealed that, although there was a worsening trend, the electrophysiological improvement was still maintained with respect to baseline conditions. The additional periods of citicoline treatment in GC patients during the subsequent 13-96 months induced a greater (p <0.01) improvement of VEP and PERG parameters with respect to pre-treatment conditions and when compared to GP patients. Thus, we observed that citicoline significantly improves retinal and cortical bioelectrical responses in glaucoma patients, suggesting a potential use of this substance in the medical treatment of glaucoma, as a complement to hypotensive therapy.
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Affiliation(s)
- Vincenzo Parisi
- Fondazione per l'Oftalmologia G.B. Bietti-ONLUS, Via Santa Maria Goretti 66, 00199, Roma, Italy.
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Parisi V, Manni GL, Olzi D, Oddone F, Coppola G, Bucci MG. Impaired neural conduction in crossed visual pathways in patients with ocular hypertension. Eur J Ophthalmol 2005; 14:486-94. [PMID: 15638097 DOI: 10.1177/112067210401400607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To evaluate the neural conduction along crossed and uncrossed visual pathways in patients with ocular hypertension (OHT). METHODS Fifteen patients (mean age 59.1+/-6.8 years) with OHT (IOP>22 mmHg, Humphrey 24-2 with mean deviation [MD]>-2 dB) were enrolled. They were compared to 15 age-matched controls. In OHT patients and control subjects, visual evoked potentials (VEPs) were recorded using full-field checkerboard patterns (the check subtended 15' of visual arc; contrast 80%) reversed at 2 Hz. VEP responses were simultaneously recorded in the homolateral visual cortex (HC) and in the contralateral visual cortex (CC), with respect to the stimulated eye. RESULTS In OHT patients, VEP P100 implicit times observed in HC and CC were both significantly delayed (analysis of variance, p<0.01) when compared to those of controls, and, in particular, longer in CC than in HC. The interhemispheric differences (ID: P100 implicit time in HC - P100 implicit time in CC) were significantly higher in OHT patients than controls (-3.16+/-1.80 msec and 1.16+/-1.04 msec, respectively, p=0.001). In OHT patients we observed an MD hemifield difference (difference between nasal and temporal MD values) higher than in controls (-0.82+/-0.80 dB and 0.04+/-1.03 dB, respectively, p<0.01) and significantly correlated with the ID (r: 0.836, p<0.001). CONCLUSIONS The observed asymmetry in the bioelectrical cortical responses and in the visual hemifield parameters suggests that crossed visual pathways could be impaired earlier than uncrossed visual pathways in OHT patients.
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Affiliation(s)
- V Parisi
- Ophthalmology Department, University of Roma Tor Vergata, Roma - Italy.
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Parisi V. Correlation between morphological and functional retinal impairment in patients affected by ocular hypertension, glaucoma, demyelinating optic neuritis and Alzheimer's disease. Semin Ophthalmol 2003; 18:50-7. [PMID: 14566623 DOI: 10.1076/soph.18.2.50.15855] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this article the correlations between the morphological evaluation of the nerve fiber layer (NFL) thickness (by OCT) and retinal functional assessment (by Pattern ERG recordings) performed in patients affected by ocular hypertension (OHT), glaucoma (OAG), demyelinating optic neuritis (MSON), and Alzheimer's disease (AD) are reported. In OHT eyes with ocular hypertension we observed that the inter-individual variation in NFL thickness is correlated with the variability of the PERG responses (the thinner the layer, the worse the visual function). In our OAG, MSON and AD eyes we observed a significant reduction in NFL thickness when compared with controls. In OHT, OAG, MSON and AD eyes abnormal PERG responses with delayed implicit times and reduced amplitudes were found. The impairment in the PERG parameters was significantly correlated to the reduction in NFL thickness. Our results suggest that in patients affected by ocular hypertension, glaucoma, demyelinating optic neuritis, and Alzheimer's Disease there is a reduction of NFL thickness evaluated "in vivo" by OCT, and this morphological involvement is correlated with electrophysiological responses assumed to be originating from the innermost retinal layers.
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Abstract
There is evidence that glaucomatous damage extends from retinal ganglion cells to vision centers in the brain. In the lateral geniculate nucleus (LGN), the major relay center between the eye and the visual cortex, neurons should undergo degenerative and/or neurochemical changes in magno-, parvo-, and koniocellular pathways conveying motion, red-green, and blue-yellow information, respectively. Furthermore, in both the LGN and visual cortex in glaucoma, changes in metabolic activity are observed. The study of brain changes in glaucoma may provide new insights into the pathobiology of glaucomatous damage and disease progression, and may stimulate new detection and therapeutic strategies to prevent blindness.
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Affiliation(s)
- N Gupta
- Department of Ophthalmology and Vision Sciences, St. Michael's Hospital, University of Toronto, Canada
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Parisi V, Restuccia R, Fattapposta F, Mina C, Bucci MG, Pierelli F. Morphological and functional retinal impairment in Alzheimer's disease patients. Clin Neurophysiol 2001; 112:1860-7. [PMID: 11595144 DOI: 10.1016/s1388-2457(01)00620-4] [Citation(s) in RCA: 245] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Our study aims to assess the optic nerve fiber layer thickness in vivo, the function of the innermost retinal layer and whether a correlation exists between morphological and functional parameters in patients affected by Alzheimer's Disease (AD). METHODS Seventeen AD patients (mean age 70.37+/-6.1 years, best corrected visual acuity >8/10 with refractive error between +/-3 sf, intra-ocular pressure (IOP)<18 mmHg) were enrolled. They were compared to 14 age-matched controls. Nerve fiber layer (NFL) thickness was measured by optical coherence tomography (OCT). Three different measurements in each quadrant (superior, inferior, nasal, and temporal) were taken and averaged. The data in all quadrants (12 values averaged) were identified as NFL Overall. Retinal function was assessed by pattern electroretinogram (PERG) recordings using high-contrast (80%) checkerboard stimuli subtending 15 min of the visual arc and reversed at the rate of two reversals/s. RESULTS In AD eyes, there was a significant (P<0.01) reduction in NFL thickness in each quadrant and in the NFL Overall evaluation compared with the values observed in control eyes. PERGs showed a significant (P<0.01) delay in N35, P50 and N95 implicit times, and reduction in N35-P50 and P50-N95 amplitudes. NFL Overall values were significantly correlated (P<0.01) to the PERG P50 and N95 implicit times and P50-N95 amplitude. No correlations (P>0.01) between NFL values and other PERG parameters (N35 implicit time, N35-P50 amplitude) were found. CONCLUSIONS Our results suggest that in AD patients, there is a reduction of NFL thickness evaluated in vivo by OCT and this morphological abnormality is related to a retinal dysfunction as revealed by abnormal PERG responses.
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Affiliation(s)
- V Parisi
- Clinica Oculistica Università di Roma Tor Vergata, Rome, Italy.
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