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Al-Nosairy KO, Duscha A, Buhr H, Lipp A, Desel C, Hegelmaier T, Thieme H, Haghikia A, Hoffmann MB. Functional and structural readouts for early detection of retinal involvement in multiple sclerosis. Front Integr Neurosci 2023; 17:1158148. [PMID: 37138797 PMCID: PMC10150010 DOI: 10.3389/fnint.2023.1158148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/30/2023] [Indexed: 05/05/2023] Open
Abstract
Introduction The retina, a window into the brain, allows for the investigation of many disease-associated inflammatory and neurodegenerative changes affecting the central nervous system (CNS). Multiple sclerosis (MS), an autoimmune disease targeting the CNS, typically impacts on the visual system including the retina. Hence, we aimed to establish innovative functional retinal measures of MS-related damage, e.g., spatially resolved non-invasive retinal electrophysiology, backed by established morphological retinal imaging markers, i.e., optical coherence tomography (OCT). Methods 20 healthy controls (HC) and 37 people with MS [17 without history of optic neuritis (NON) and 20 with (HON) history of optic neuritis] were included. In this work, we differentially assessed photoreceptor/bipolar cells (distal retina) and retinal ganglion cell (RGC, proximal retina) function besides structural assessment (OCT). We compared two multifocal electroretinography-based approaches, i.e., the multifocal pattern electroretinogram (mfPERG) and the multifocal electroretinogram to record photopic negative response (mfERG PhNR ). Structural assessment utilized peripapillary retinal nerve fiber layer thickness (pRNFL) and macular scans to calculate outer nuclear thickness (ONL) and macular ganglion cell inner plexiform layer thickness (GCIPL). One eye was randomly selected per subject. Results In NON, photoreceptor/bipolar cell layer had dysfunctional responses evidenced by reduced mfERG PhNR -N1 peak time of the summed response, but preserved structural integrity. Further, both NON and HON demonstrated abnormal RGC responses as evidenced by the photopic negative response of mfERG PhNR (mfPhNR) and mfPERG indices (P < 0.05). Structurally, only HON had thinned retina at the level of RGCs in the macula (GCIPL, P < 0.01) and the peripapillary area (pRNFL, P < 0.01). All three modalities showed good performance to differentiate MS-related damage from HC, 71-81% area under curve. Conclusion In conclusion, while structural damage was evident mainly for HON, functional measures were the only retinal read-outs of MS-related retinal damage that were independent of optic neuritis, observed for NON. These results indicate retinal MS-related inflammatory processes in the retina prior to optic neuritis. They highlight the importance of retinal electrophysiology in MS diagnostics and its potential as a sensitive biomarker for follow-up in innovative interventions.
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Affiliation(s)
- Khaldoon O. Al-Nosairy
- Department of Ophthalmology, University Hospital Magdeburg, Magdeburg, Germany
- *Correspondence: Khaldoon O. Al-Nosairy,
| | - Alexander Duscha
- Department of Neurology, University Hospital Magdeburg, Magdeburg, Germany
| | - Henrike Buhr
- Department of Ophthalmology, University Hospital Magdeburg, Magdeburg, Germany
| | - Antonia Lipp
- Department of Neurology, University Hospital Magdeburg, Magdeburg, Germany
| | - Christiane Desel
- Department of Neurology, University Hospital Magdeburg, Magdeburg, Germany
| | - Tobias Hegelmaier
- Department of Neurology, University Hospital Magdeburg, Magdeburg, Germany
| | - Hagen Thieme
- Department of Ophthalmology, University Hospital Magdeburg, Magdeburg, Germany
| | - Aiden Haghikia
- Department of Neurology, University Hospital Magdeburg, Magdeburg, Germany
| | - Michael B. Hoffmann
- Department of Ophthalmology, University Hospital Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
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Marmoy OR, Viswanathan S. Clinical electrophysiology of the optic nerve and retinal ganglion cells. Eye (Lond) 2021; 35:2386-2405. [PMID: 34117382 PMCID: PMC8377055 DOI: 10.1038/s41433-021-01614-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/11/2021] [Accepted: 05/19/2021] [Indexed: 12/28/2022] Open
Abstract
Clinical electrophysiological assessment of optic nerve and retinal ganglion cell function can be performed using the Pattern Electroretinogram (PERG), Visual Evoked Potential (VEP) and the Photopic Negative Response (PhNR) amongst other more specialised techniques. In this review, we describe these electrophysiological techniques and their application in diseases affecting the optic nerve and retinal ganglion cells with the exception of glaucoma. The disease groups discussed include hereditary, compressive, toxic/nutritional, traumatic, vascular, inflammatory and intracranial causes for optic nerve or retinal ganglion cell dysfunction. The benefits of objective, electrophysiological measurement of the retinal ganglion cells and optic nerve are discussed, as are their applications in clinical diagnosis of disease, determining prognosis, monitoring progression and response to novel therapies.
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Affiliation(s)
- Oliver R Marmoy
- Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK.
- UCL-GOS Institute for Child Health, University College London, London, UK.
- Manchester Metropolitan University, Manchester, UK.
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Al-Nosairy KO, Hoffmann MB, Bach M. Non-invasive electrophysiology in glaucoma, structure and function-a review. Eye (Lond) 2021; 35:2374-2385. [PMID: 34117381 PMCID: PMC8376952 DOI: 10.1038/s41433-021-01603-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/08/2021] [Accepted: 05/10/2021] [Indexed: 11/09/2022] Open
Abstract
Glaucoma, its early diagnosis, and monitoring of interventions remain an ongoing challenge. We here review developments in functional assessment and its relation to morphology, evaluating recent insights in electrophysiology in glaucoma and highlighting how glaucoma research and diagnostics benefit from combined approaches of OCT and electrophysiological investigations. After concise overviews of OCT and non-invasive electrophysiology in glaucoma, we evaluate commonalities and complementarities of OCT and electrophysiology for our understanding of glaucoma. As a specific topic, the dynamic range (floor effects) of the various techniques is discussed.
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Affiliation(s)
| | - Michael B Hoffmann
- Department of Ophthalmology, Otto-von-Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Michael Bach
- Faculty of Medicine, Eye Center, Medical Center-University of Freiburg, Freiburg im Breisgau, Germany.
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Al-Nosairy KO, Horbrügger M, Schippling S, Wagner M, Haghikia A, Pawlitzki M, Hoffmann MB. Structure-Function Relationship of Retinal Ganglion Cells in Multiple Sclerosis. Int J Mol Sci 2021; 22:ijms22073419. [PMID: 33810342 PMCID: PMC8037992 DOI: 10.3390/ijms22073419] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 11/16/2022] Open
Abstract
The retinal ganglion cells (RGC) may be considered an easily accessible pathophysiological site of degenerative processes in neurological diseases, such as the RGC damage detectable in multiple sclerosis (MS) patients with (HON) and without a history of optic neuritis (NON). We aimed to assess and interrelate RGC functional and structural damage in different retinal layers and retinal sites. We included 12 NON patients, 11 HON patients and 14 healthy controls for cross-sectional multifocal pattern electroretinography (mfPERG) and optical coherence tomography (OCT) measurements. Amplitude and peak times of the mfPERG were assessed. Macula and disc OCT scans were acquired to determine macular retinal layer and peripapillary retinal nerve fiber layer (pRNFL) thickness. In both HON and NON patients the foveal N2 amplitude of the mfPERG was reduced compared to controls. The parafoveal P1 peak time was significantly reduced in HON only. For OCT, parafoveal (pfGCL) and perifoveal (pGCL) ganglion cell layer thicknesses were decreased in HON vs. controls, while pRNFL in the papillomacular bundle sector (PMB) showed reductions in both NON and HON. As the mfPERG derived N2 originates from RGC axons, these findings suggest foveal axonal dysfunction not only in HON, but also in NON patients.
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Affiliation(s)
- Khaldoon O. Al-Nosairy
- Department of Ophthalmology, University Hospital Magdeburg, 39120 Magdeburg, Germany; (K.O.A.-N.); (M.W.)
| | - Marc Horbrügger
- Department of Dermatology, University Hospital Magdeburg, 39120 Magdeburg, Germany;
| | - Sven Schippling
- Multimodal Imaging in Neuro-Immunological Diseases (MINDS), University of Zurich, 8057 Zurich, Switzerland;
- Center for Neuroscience Zurich (ZNZ), ETH Zurich, 8057 Zurich, Switzerland
| | - Markus Wagner
- Department of Ophthalmology, University Hospital Magdeburg, 39120 Magdeburg, Germany; (K.O.A.-N.); (M.W.)
| | - Aiden Haghikia
- Department of Neurology, University Hospital Magdeburg, 39120 Magdeburg, Germany;
| | - Marc Pawlitzki
- Department of Neurology, Institute of Translational Neurology, University Hospital Münster, 48149 Münster, Germany;
| | - Michael B. Hoffmann
- Department of Ophthalmology, University Hospital Magdeburg, 39120 Magdeburg, Germany; (K.O.A.-N.); (M.W.)
- Center for Behavioral Brain Sciences, 39120 Magdeburg, Germany
- Correspondence: ; Tel.: +49-391-6713585
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Visual loss and recovery in chiasmal compression. Prog Retin Eye Res 2019; 73:100765. [DOI: 10.1016/j.preteyeres.2019.06.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/05/2019] [Accepted: 06/12/2019] [Indexed: 12/18/2022]
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Muranyi DS, Kramer FH, Herbik A, Hoffmann MB. Scotopic multifocal visual evoked potentials. Clin Neurophysiol 2019; 130:379-387. [PMID: 30677707 DOI: 10.1016/j.clinph.2018.11.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/24/2018] [Accepted: 11/27/2018] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To investigate the scope of scotopic multifocal visual evoked potentials (mfVEPS) for the assessment of scotopic visual fields. METHODS Pattern-reversal mfVEP for photopic (mfVEPP) and scotopic conditions (mfVEPS; 0.003 cd/m2) were recorded from 36 visual field locations of a circular checkerboard pattern (25° radius) in 9 participants with normal vision. MfVEPP were recorded with a conventional central fixation cross, mfVEPS were recorded (i) with (mfVEPS+) and (ii) without (mfVEPS-) an additional fixation aid. Latency shifts were determined using cross-correlations, mfVEP magnitudes were analysed in an eccentricity dependent manner using signal-to-noise ratios (SNRs). RESULTS In comparison to mfVEPP, mfVEPS- and mfVEPS+ were delayed by 101 ms and 97 ms, respectively, and had smaller signal-to-noise-ratios. Both mfVEPS were reduced down to noise level in the center and also severely reduced for the most peripheral stimulus eccentricity used. The visual-field-coverage for the paracentral eccentricities of mfVEPS+ and mfVEPS- was 76% and 65% [4°-9°], respectively, and 79% and 66% [9°-16°]. CONCLUSIONS MfVEPS were delayed compared to mfVEPP and demonstrated the expected central response drop-out typical for scotopic vision. SIGNIFICANCE MfVEPS may hold promise of an objective, spatially resolved visual field test which motivates testing it in patients with diseases affecting scotopic vision.
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Affiliation(s)
- D S Muranyi
- Department of Ophthalmology, Otto-von-Guericke University Magdeburg, Germany; Department of Ophthalmology, Martin-Luther University Halle, Germany
| | - F H Kramer
- Department of Ophthalmology, Otto-von-Guericke University Magdeburg, Germany; Beuth University of Applied Sciences, Berlin, Germany
| | - A Herbik
- Department of Ophthalmology, Otto-von-Guericke University Magdeburg, Germany
| | - M B Hoffmann
- Department of Ophthalmology, Otto-von-Guericke University Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany.
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Bach M, Cuno AK, Hoffmann MB. Retinal conduction speed analysis reveals different origins of the P50 and N95 components of the (multifocal) pattern electroretinogram. Exp Eye Res 2018; 169:48-53. [PMID: 29374551 DOI: 10.1016/j.exer.2018.01.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 01/04/2018] [Accepted: 01/21/2018] [Indexed: 11/26/2022]
Abstract
The pattern electroretinogram (PERG), an indicator of retinal ganglion cell (RGC) function, comprises a P50 and an N95 component. We addressed the question of whether the N95 originates, like the P50, from the RGC bodies or from the change of axon orientation at the optic nerve head (ONH). Thus, we recorded multifocal PERGs for 36 retinal locations in 21 participants. Second-order kernel responses were analyzed for the dependence of peak time topography on retinal fiber lengths to the ONH separately for the positive and negative excursions. We found that peak times were longer for macular [P1 (P50-like): 50 ms; N2 (N95-like): 76)] than for peripheral responses [P1: 43; N2: 66]. For the N2 another factor was necessary to explain the variability: The time difference (deltaT: N2 minus P1) was found to be proportional to fiber length from ganglion cell body to the ONH. We calculated retinal fiber length using an analytical function by Jansonius et al. (2009, 2012) and found that a linear model with factors eccentricity and fiber length explained 82% of the total N2 time variance (p«0.001). The conduction speeds of the retinal axons were estimated from deltaT to range from 0.5 to 3.0 m/s for parafovea and periphery, respectively. The dependence of deltaT on the distance from ganglion cell body to the ONH suggests that the N2 originates at the ONH rather than at the ganglion cell body. While the multifocal N2 peaks earlier (≈76 ms) than the non-multifocal PERG-N95 (≈95 ms), considerations of high-pass filtering and frequency dependence of the mfPERG-N2 suggest that the source separation (P50 = ganglion cell body vs. N95 = ONH) also holds for the non-multifocal PERG.
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Affiliation(s)
- Michael Bach
- University Eye Center, Medical Center - University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany.
| | - Anne-Kathrin Cuno
- Visual Processing Laboratory, Universitäts-Augenklinik, Magdeburg, Germany
| | - Michael B Hoffmann
- Visual Processing Laboratory, Universitäts-Augenklinik, Magdeburg, Germany; Center for Behavioural Brain Sciences, Magdeburg, Germany
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Saul AB, Still AE. Multifocal Electroretinography in the Presence of Temporal and Spatial Correlations and Eye Movements. Vision (Basel) 2016; 1:E3. [PMID: 31740628 PMCID: PMC6849053 DOI: 10.3390/vision1010003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/18/2016] [Accepted: 05/03/2016] [Indexed: 11/21/2022] Open
Abstract
Releasing patients from the fixation task, and permitting them to view natural stimuli such as movies, would provide increased comfort, and potentially additional signs of retinal function, when recording multifocal electroretinograms (mfERGs). Techniques must be developed to handle the difficulties that arise from these alternative stimulation strategies. Multifocal stimuli were presented to volunteer human subjects with and without fixation. Retinocentric analyses were performed to deal with shifts of the stimulus across the retina in the presence of eye movements. Artificial scotomas that moved with the eyes to simulate local retinal defects were presented to assess whether such defects might be detectable in the presence of eye movements. Temporal and spatial correlations in the stimulus can be discounted, permitting retinal kernels to be measured in response to natural stimuli. Responses to temporally natural stimuli tend to have slightly stronger amplitudes because of the presence of low temporal frequencies in these stimuli. The effects of eye movement artifacts can be reduced, permitting similar kernels to be obtained in the absence and presence of eye movements. Convergence to stable kernels took slightly longer in the presence of temporal correlations or eye movements. Artificial scotomas can be localized with these methods. It may be possible to perform multifocal ERG recordings in the clinic using more flexible, natural techniques. However, work is needed to achieve results comparable to those routinely obtained with conventional methods.
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Affiliation(s)
- Alan B. Saul
- Department of Ophthalmology, and James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
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Differential effects of optic media opacities on simultaneous multifocal pattern electroretinograms and visual evoked potentials. Clin Neurophysiol 2014; 125:2418-26. [DOI: 10.1016/j.clinph.2014.03.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 03/05/2014] [Accepted: 03/18/2014] [Indexed: 11/23/2022]
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Bach M, Poloschek CM. Electrophysiology and glaucoma: current status and future challenges. Cell Tissue Res 2013; 353:287-96. [PMID: 23525754 DOI: 10.1007/s00441-013-1598-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/21/2013] [Indexed: 11/25/2022]
Abstract
Visual electrophysiology allows non-invasive monitoring of the function of most processing stages along the visual pathway. Here, we consider which of the available methods provides the most information concerning glaucomatous optic nerve disease. The multifocal electroretinogram (ERG), although often employed, is less affected in glaucoma than two direct measurements of retinal ganglion cell function, namely the pattern ERG (PERG) and the photopic negative response (PhNR) of the ERG. For the PERG, longitudinal studies have been reported, suggesting that this method can be used for the early detection of glaucoma; for the PhNR, no longitudinal study is available as yet. The multifocal PERG can spatially resolve ganglion cell function but its glaucomatous reduction is typically panretinal, even with only local field changes and so, its topographic resolution is of no advantage in glaucoma. The multifocal visual evoked potential promises objective perimetry and shows sensitivity and specificity comparable with standard automated perimetry but has not been established as a routine tool to date.
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Affiliation(s)
- Michael Bach
- Section Visual Function, Department of Ophthalmology, University of Freiburg, Freiburg, Germany.
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Herbik A, Hölzl GC, Reupsch J, Hoffmann MB. Differential effects of optic media opacities on mfERGs and mfVEPs. Clin Neurophysiol 2013; 124:1225-31. [PMID: 23352815 DOI: 10.1016/j.clinph.2012.11.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/21/2012] [Accepted: 11/28/2012] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess different effects of image degradation that could result from optic media opacities on multifocal retinal (mfERG) and cortical responses (mfVEP). METHODS Monocular flash-mfERGs and pattern-reversal mfVEPs were recorded. MfERG-P1 amplitudes and implicit times and mfVEP root-mean-square values (RMS) and delays were compared for different filter conditions (none, 8% luminance, 50% luminance, 50% luminance plus blur) in a total of ten participants with normal vision. RESULTS Reducing stimulus luminance down to 50% and 8% reduced mfERG amplitudes to 86% and 42%, respectively, with no significant effect on mfVEP amplitude. Implicit times were increased for mfERGs by 0.9 ms and 6.0 ms, respectively, and for mfVEPs by 1.0 ms and 6.3 ms, respectively. For '50% luminance plus blur' mfERG amplitudes were significantly reduced centrally and enhanced peripherally and delayed by 1.3 ms. MfVEPs were reduced close to noise level independent of eccentricity. CONCLUSIONS Degradation of the retinal image is a potential source of discrepancies between mfERGs and mfVEPs. Image blur suppresses the mfVEP at all locations and changes mfERG topography, resulting in a selective loss of central responses. SIGNIFICANCE Considering optic media opacities is of importance for the correct interpretation of mfERG and mfVEP recordings, particularly in elderly patients.
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Affiliation(s)
- A Herbik
- Visual Processing Laboratory, Ophthalmology, Otto-von-Guericke-University, Magdeburg, Germany
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Correlation between multifocal pattern electroretinography and Fourier-domain OCT in eyes with temporal hemianopia from chiasmal compression. Graefes Arch Clin Exp Ophthalmol 2012; 251:903-15. [PMID: 23052713 DOI: 10.1007/s00417-012-2156-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/25/2012] [Accepted: 09/03/2012] [Indexed: 10/27/2022] Open
Abstract
PURPOSE To evaluate the correlation between multifocal pattern electroretinography (mfPERG) and Fourier-domain optical coherence tomography (FD-OCT) with regard to macular and retinal nerve fiber layer (RNFL) thickness in eyes with temporal hemianopia from chiasmal compression. METHODS Twenty-five eyes from 25 patients with permanent temporal visual field defects from chiasmal compression and 25 healthy eyes were submitted to mfPERG using a stimulus pattern of 19 rectangles, standard automated perimetry and FD-OCT measurements. The mfPERG response was determined for groups of three rectangles for the nasal and temporal hemifields and for each quadrant. Macular thickness measurements were registered according to an overlaid OCT-generated checkerboard with 36 checks and averaged for the central area, and for each scanned quadrant and hemifield. RNFL thickness was determined for all twelve 30-degree segments around the disc, and averaged for the segments corresponding to the 6, 7, 8, 9, 10, 11 and 12 o'clock position. Correlations were verified with Pearson's correlation coefficients and linear regression analysis. RESULTS Both mfPERG amplitudes and OCT measurements were significantly smaller in eyes with temporal visual field defects than in normals. A significant and strong correlation was found between most mfPERG and macular or RNFL thickness OCT parameters. CONCLUSIONS mfPERG amplitudes and OCT measurements are significantly correlated in patients with chiasmal compression. Both technologies can quantify neuronal loss and, if used in combination, may help clarify structure-function relationships in this patient population.
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Souza GS, Schakelford HB, Moura ALA, Gomes BD, Ventura DF, Fitzgerald MEC, Silveira LCL. Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation. Braz J Med Biol Res 2012; 45:955-61. [PMID: 22782556 PMCID: PMC3854182 DOI: 10.1590/s0100-879x2012007500112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/04/2012] [Indexed: 12/04/2022] Open
Abstract
This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m2 mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.
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Affiliation(s)
- G S Souza
- Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, PA, Brasil.
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Hagan RP, Fisher AC, Brown MC. Investigation of the temporal properties of the retina using the m-sequence. Doc Ophthalmol 2011; 123:179-85. [PMID: 22020345 DOI: 10.1007/s10633-011-9295-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 10/10/2011] [Indexed: 10/16/2022]
Abstract
The mfERG provides a topographic map of function of the retina and has been used in numerous studies to identify macular, paramacular and peripheral retinal dysfunction. This study investigates the changes in response due to the presentation rate of the stimulus. Twenty subjects gave informed consent to take part in the study, which had local regional ethical committee approval. Only a single hexagon of 8° diameter was presented to reduce ambiguity when identifying the higher-order kernels (HOK). Six rates were tested using a 60-Hz CRT monitor by introducing blank (black ~0 cd/m2) filler frames (FF). The rates tested were 0FF; 1FF; 2FF; 4FF; 7FF; and 14FF. The first-order kernel had largest responses to the slower stimuli (4FF and above). HOK had largest amplitudes at faster rates with the second-order kernel peaking at 1FF. At rates with 4FF and slower, the higher-order kernels were indiscernible above the noise.
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Affiliation(s)
- Richard P Hagan
- Department of Medical Physics and Clinical Engineering, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK.
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Effect of blue-light filtering on multifocal visual-evoked potentials. J Cataract Refract Surg 2011; 38:85-91. [PMID: 22001106 DOI: 10.1016/j.jcrs.2011.06.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Revised: 06/18/2011] [Accepted: 06/22/2011] [Indexed: 11/21/2022]
Abstract
PURPOSE To perform an objective functional assessment of the impact of blue-light filters on cortical processing to evaluate the potential side effects of the filters on higher tier visual function at the neural level. SETTING Department of Ophthalmology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany. DESIGN Cohort study. METHODS Multifocal pattern-reversal visual-evoked potentials (multifocal VEPs) were recorded monocularly in pseudophakic patients with a clear intraocular lens (IOL) under 2 conditions: (1) stimulus perception through a yellow filter with the filter characteristics of an AF-1 YA-60BB IOL (blue filtering); (2) stimulus perception through a neutral filter that homogeneously attenuates the effective stimulus intensity as under the blue-light filtering condition but independent of the wavelength (neutral filtering). Second-order kernel multifocal VEPs were extracted for 60 visual field locations, and amplitude and latency effects were determined for 6 stimulus eccentricities. RESULTS The study evaluated 20 patients. Typical multifocal VEPs were obtained for the blue-light and neutral filtering conditions at all eccentricities. No significant effects on amplitudes were obtained, and a subtle latency effect (<0.5 millisecond delay for neutral filtering; P<.02) did not reach significance in an eccentricity-specific analysis. CONCLUSIONS The induced short-term change in the spectral composition of the visual stimulus left neural activity at the level of the primary visual cortex largely unaffected, providing an objective account of the integrity of visual processing under this condition.
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Abstract
PURPOSE To review the efficacy of the pattern electroretinogram (PERG) in early diagnosis of glaucoma. METHODS Stimulation parameters of check size and temporal frequency are considered. Analyses of various peaks (P50, N95, the N95/P50) and Fourier steady-state are considered. The relation to visual field defects is explored. RESULTS The PERG is markedly alterated in glaucoma. It shows amplitude reductions in (still) normal areas of the visual field. Optical imaging on the retina needs to be optimal. Higher temporal frequency (>10 reversals/s) improves the sensitivity to detect glaucoma compared with transient stimulation. The ratio between the amplitudes to 0.8 degrees checks and to 16 degrees checks, "PERG ratio," exploits a check size-specific reduction in early glaucoma and reduces variability. Longitudinal studies suggest that the PERG can indicate incipient glaucoma damage before evidence from the visual field. CONCLUSIONS The PERG is a demanding electrophysiological technique that can serve as a sensitive biomarker for retinal ganglion cell function. With appropriate paradigms, PERG assists in identifying those patients with elevated interocular pressure in whom glaucoma damage is incipient before visual field changes occur.
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