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Ly K, Guo T, Tsai D, Muralidharan M, Shivdasani MN, Lovell NH, Dokos S. Simulating the impact of photoreceptor loss and inner retinal network changes on electrical activity of the retina. J Neural Eng 2022; 19. [PMID: 36368033 DOI: 10.1088/1741-2552/aca221] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 11/11/2022] [Indexed: 11/13/2022]
Abstract
Objective.A major reason for poor visual outcomes provided by existing retinal prostheses is the limited knowledge of the impact of photoreceptor loss on retinal remodelling and its subsequent impact on neural responses to electrical stimulation. Computational network models of the neural retina assist in the understanding of normal retinal function but can be also useful for investigating diseased retinal responses to electrical stimulation.Approach.We developed and validated a biophysically detailed discrete neuronal network model of the retina in the software package NEURON. The model includes rod and cone photoreceptors, ON and OFF bipolar cell pathways, amacrine and horizontal cells and finally, ON and OFF retinal ganglion cells with detailed network connectivity and neural intrinsic properties. By accurately controlling the network parameters, we simulated the impact of varying levels of degeneration on retinal electrical function.Main results.Our model was able to reproduce characteristic monophasic and biphasic oscillatory patterns seen in ON and OFF neurons during retinal degeneration (RD). Oscillatory activity occurred at 3 Hz with partial photoreceptor loss and at 6 Hz when all photoreceptor input to the retina was removed. Oscillations were found to gradually weaken, then disappear when synapses and gap junctions were destroyed in the inner retina. Without requiring any changes to intrinsic cellular properties of individual inner retinal neurons, our results suggest that changes in connectivity alone were sufficient to give rise to neural oscillations during photoreceptor degeneration, and significant network connectivity destruction in the inner retina terminated the oscillations.Significance.Our results provide a platform for further understanding physiological retinal changes with progressive photoreceptor and inner RD. Furthermore, our model can be used to guide future stimulation strategies for retinal prostheses to benefit patients at different stages of disease progression, particularly in the early and mid-stages of RD.
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Affiliation(s)
- Keith Ly
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - Tianruo Guo
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - David Tsai
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia.,School of Electrical Engineering & Telecommunications, UNSW, Sydney, NSW 2052, Australia
| | | | - Mohit N Shivdasani
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia.,Tyree Institute of Health Engineering (IHealthE), UNSW, Sydney, NSW 2052, Australia
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
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Byun MS, Park SW, Lee JH, Yi D, Jeon SY, Choi HJ, Joung H, Ghim UH, Park UC, Kim YK, Shin SA, Yu HG, Lee DY. Association of Retinal Changes With Alzheimer Disease Neuroimaging Biomarkers in Cognitively Normal Individuals. JAMA Ophthalmol 2021; 139:548-556. [PMID: 33764406 DOI: 10.1001/jamaophthalmol.2021.0320] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Importance Retinal biomarkers reflecting in vivo brain Alzheimer disease (AD) pathologic abnormalities could be a useful tool for screening cognitively normal (CN) individuals at the preclinical stage of AD. Objectives To investigate the association of both functional and structural alterations of the retina with in vivo AD pathologic abnormalities in CN older adults and model a screening tool for detection of preclinical AD. Design, Setting, and Participants This cross-sectional study included a total of 49 CN individuals, and all assessment was done at the Seoul National University Hospital, Seoul, South Korea. All participants underwent complete ophthalmic examination, including swept-source optical coherence tomography (SS-OCT) and multifocal electroretinogram as well as amyloid-β (Aβ) positron emission tomography and magnetic resonance imaging. Data were collected from January 1, 2016, through October 31, 2017, and analyzed from February 1, 2018, through June 30, 2020. Main Outcomes and Measures For structural parameters of the retina, the thickness of the macula and layer-specific thicknesses, including peripapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer measured by SS-OCT, were used for analysis. For functional parameters of the retina, implicit time and amplitude of rings 1 to 6 measured by multifocal electroretinogram were used. Results Of the 49 participants, 25 were women (51.0%); mean (SD) age was 70.6 (9.4) years. Compared with 33 CN individuals without Aβ deposition (Aβ-CN), the 16 participants with Aβ (Aβ+CN) showed reduced inner nasal macular thickness (mean [SD], 308.9 [18.4] vs 286.1 [22.5] μm; P = .007) and retinal nerve fiber layer thickness, particularly in the inferior quadrant (133.8 [17.9] vs 103.8 [43.5] μm; P = .003). In addition, the Aβ+CN group showed prolonged implicit time compared with the Aβ-CN group, particularly in ring 5 (41.3 [4.0] vs 38.2 [1.3] milliseconds; P = .002). AD-related neurodegeneration was correlated with the thickness of the ganglion cell-inner plexiform layer only (r = 0.41, P = .005). The model to differentiate the Aβ+CN vs Aβ-CN groups derived from the results showed 90% accuracy. Conclusions and Relevance The findings of this study showing both functional as well as structural changes of retina measured by multifocal electroretinogram and SS-OCT in preclinical AD suggest the potential use of retinal biomarkers as a tool for early detection of in vivo AD pathologic abnormalities in CN older adults.
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Affiliation(s)
- Min Soo Byun
- Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Sung Wook Park
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea.,Retinal Degeneration Laboratory, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.,Seran Eye Center, Seoul, Republic of Korea
| | - Jun Ho Lee
- Department of Neuropsychiatry, National Center for Mental Health, Seoul, Republic of Korea
| | - Dahyun Yi
- Institute of Human Behavioral Medicine, Medical Research Center Seoul National University, Seoul, Republic of Korea
| | - So Yeon Jeon
- Department of Neuropsychiatry, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Hyo Jung Choi
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Haejung Joung
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Un Hyung Ghim
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea.,Retinal Degeneration Laboratory, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Un Chul Park
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea.,Retinal Degeneration Laboratory, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Yu Kyeong Kim
- Department of Nuclear Medicine, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea
| | - Seong A Shin
- Department of Nuclear Medicine, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea
| | - Hyeong Gon Yu
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea.,Retinal Degeneration Laboratory, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Dong Young Lee
- Institute of Human Behavioral Medicine, Medical Research Center Seoul National University, Seoul, Republic of Korea.,Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea.,Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea
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Giambene B, Verdina T, Pennino M, Fabbrucci M, Cavallini GM, Menchini U. Multifocal electroretinographic responses in sector retinitis pigmentosa. Int Ophthalmol 2020; 40:703-8. [PMID: 31758507 DOI: 10.1007/s10792-019-01231-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/16/2019] [Indexed: 10/25/2022]
Abstract
HEADINGS Multifocal electroretinography (mfERG) may be useful in the management of sector retinitis pigmentosa (SRP). AIM To compare multifocal electroretinographic responses in SRP, generalised retinitis pigmentosa (GRP), and healthy controls. METHODS Eighteen patients with SRP, twelve with GRP, and fifteen controls were included in the study. All participants underwent: complete ophthalmological examination, Humphrey visual field testing, full-field ERG, and mfERG. The mean P1 amplitude, the implicit time (IT), and the mapping of the local responses were evaluated. RESULTS The mean P1 amplitude was higher in the SRPs than in GRPs (p < 0.001), while it did not differ between SRPs and controls (p = 0.913). In the SRPs, the P1 amplitude in pathologic areas was higher than in the GRPs (p < 0.001). In normal areas, this parameter did not differ from the controls (p = 0.499). Moreover, in the SRPs, no differences in the P1 amplitude and the IT between pigmented and non-pigmented areas were found. CONCLUSION In the present study, the mfERG examination displayed significant differences between sector and generalised RP, showing normal values in sector RP even in pigmented areas. Considering the patients included in this study, SRP seems to represent a favourable variant of the disease, characterised by a limited retinal involvement and apparently mild functional damage. It is still unclear how these results can be extended to other forms of SRP.
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Farkas Ä. Electroretinography (ERG): Electrophysiological Examination of the Retina. Neuroophthalmology 2016. [DOI: 10.1007/978-3-319-28956-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Lopez Torres LT, Türksever C, Schötzau A, Orgül S, Todorova MG. Peripapillary retinal vessel diameter correlates with mfERG alterations in retinitis pigmentosa. Acta Ophthalmol 2015; 93:e527-33. [PMID: 25809154 DOI: 10.1111/aos.12707] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 02/06/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE To investigate relationship between the peripapillary retinal vessel diameter and the residual retinal function, measured by mfERG, in patients with retinitis pigmentosa (RP). PATIENTS AND METHODS A cross-sectional study based on 23 patients with RP (43 eyes) and 20 controls (40 eyes) was performed. Retinal vessel diameters were measured using a computer-based program of the retinal vessel analyser (RVA; IMEDOS Systems UG, Jena, Germany). We evaluated the mean diameter in all four major retinal arterioles (D-A) and venules (D-V) within 1.0-1.5 optic disc diameters from the disc margin. The data were compared with the N1 amplitudes (measured from the baseline to the trough of the first negative wave), with the N1P1 amplitudes (measured from the trough of the first negative wave to the peak of the first positive wave) of the mfERG overall response and with the mfERG responses averaged in zones [zone 1 (0°-3°), zone 2 (3°-8°), zone 3 (8°-15°) and zone 4 (15°-24°)]. RESULTS Mean (±SD) D-A and D-V were narrower in patients with RP [84.86 μm (±13.37 μm) and 103.35 μm (±13.65 μm), respectively] when compared to controls [92.81 μm (±11.49 μm) and 117.67 μm (±11.93 μm), respectively; the p-values between groups were p = 0.003 for D-A and p < 0.001 for D-V, linear mixed-effects model]. The RP group revealed clear differences compared to the controls: D-A and D-V became narrower with reduced mfERG responses. D-V correlated significantly with the overall mfERG N1 amplitudes (p = 0.013) and with N1P1 amplitudes (p = 0.016). D-V correlated with the mfERG amplitudes averaged in zones: (zone 2, 3 and 4; p ≤ 0.040) and N1P1 mfERG amplitudes (zones 1, 2, 3 and 4; p ≤ 0.013). CONCLUSIONS Peripapillary retinal vessel diameter is reduced in RP proportionally to functional alterations.
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Affiliation(s)
| | - Cengiz Türksever
- Department of Ophthalmology; University of Basel; Basel Switzerland
| | - Andreas Schötzau
- Department of Ophthalmology; University of Basel; Basel Switzerland
| | - Selim Orgül
- Department of Ophthalmology; University of Basel; Basel Switzerland
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Sujirakul T, Lin MK, Duong J, Wei Y, Lopez-Pintado S, Tsang SH. Multimodal Imaging of Central Retinal Disease Progression in a 2-Year Mean Follow-up of Retinitis Pigmentosa. Am J Ophthalmol 2015; 160:786-98.e4. [PMID: 26164827 DOI: 10.1016/j.ajo.2015.06.032] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 06/28/2015] [Accepted: 06/30/2015] [Indexed: 11/25/2022]
Abstract
PURPOSE To determine the rate of progression and optimal follow-up time in patients with advanced-stage retinitis pigmentosa (RP) comparing the use of fundus autofluorescence imaging and spectral-domain optical coherence tomography. DESIGN Retrospective analysis of progression rate. METHODS Longitudinal imaging follow-up in 71 patients with retinitis pigmentosa was studied using the main outcome measurements of hyperautofluoresent ring horizontal diameter and vertical diameter along with ellipsoid zone line width from spectral-domain optical coherence tomography. Test-retest reliability and the rate of progression were calculated. The interaction between the progression rates was tested for sex, age, mode of inheritance, and baseline measurement size. Symmetry of left and right eye progression rate was also tested. RESULTS Significant progression was observed in >75% of patients during the 2-year mean follow-up. The mean annual progression rates of ellipsoid zone line and hyperautofluorescent ring horizontal diameter and vertical diameter were 0.45 degree (4.9%), 0.51 degree (4.1%), and 0.42 degree (4.0%), respectively. The ellipsoid zone line width and hyperautofluorescent ring horizontal diameter and vertical diameter had low test-retest variabilities of 8.9%, 9.5%, and 9.6%, respectively. This study is the first to demonstrate asymmetrical structural progression rate between right and left eye, which was found in 19% of patients. The rate of progression was significantly slower as the disease approached the fovea, supporting the theory that RP progresses in an exponential fashion. No significant interaction between progression rate and patient age, sex, or mode of inheritance was observed. CONCLUSIONS Fundus autofluorescence and optical coherence tomography detect progression in patients with RP reliably and with strong correlation. These parameters may be useful alongside functional assessments as the outcome measurements for future therapeutic trials. Follow-up at 1-year intervals should be adequate to efficiently detect progression.
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Chang S, Vaccarella L, Olatunji S, Cebulla C, Christoforidis J. Diagnostic challenges in retinitis pigmentosa: genotypic multiplicity and phenotypic variability. Curr Genomics 2012; 12:267-75. [PMID: 22131872 PMCID: PMC3131734 DOI: 10.2174/138920211795860116] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 04/06/2011] [Accepted: 04/15/2011] [Indexed: 12/03/2022] Open
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal disorders. Diagnosis can be challenging as more than 40 genes are known to cause non-syndromic RP and phenotypic expression can differ significantly resulting in variations in disease severity, age of onset, rate of progression, and clinical findings. We describe the clinical manifestations of RP, the more commonly known causative gene mutations, and the genotypic-phenotypic correlation of RP.
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Affiliation(s)
- Susie Chang
- Retina Division, Havener Eye Institute, The Ohio State University College of Medicine, Columbus, Ohio, USA
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Moon CH, Park TK, Ohn YH. Association between multifocal electroretinograms, optical coherence tomography and central visual sensitivity in advanced retinitis pigmentosa. Doc Ophthalmol 2012; 125:113-22. [PMID: 22865472 DOI: 10.1007/s10633-012-9342-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 06/27/2012] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate the association between automated perimetry, multifocal electroretinogram (mfERG) and optical coherence tomography (OCT) measurements in patients with advanced retinitis pigmentosa (RP). METHODS Twenty-five patients with advanced RP were included. Central visual field sensitivity (VFS) was evaluated using an average of visual sensitivity value at central four test points during central 30-2 static automated perimetry. OCT imaging was conducted, and the inner and outer segment (IS/OS) line was classified into three groups: Group 1, absence; Group 2, partially intact; and Group 3, intact. Central retinal thickness (CRT) that is the retinal thickness of central 3.0 mm was also evaluated. Average amplitude and implicit time of N1 and P1 in ring 1 and 2 were measured on mfERG. Comparisons of VFS, mfERG and OCT among the three subgroups were performed following IS/OS integrity. Relationship among VFS, mfERG and CRT was evaluated by regression analysis. RESULTS Group 3 patients with an intact IS/OS line showed a better VFS, and amplitude of mfERG response than those of Group 1 and 2. VFS and amplitudes of mfERG were correlated significantly with CRT in linear regression analysis. CONCLUSIONS Disrupted IS/OS integrity was associated with visual dysfunction which was shown by decreased amplitude of mfERG response and reduced central VFS. CRT was significantly correlated with amplitude of mfERG response and central VFS. An eye with the more reduced CRT was associated with the worse amplitude of mfERG response and central VFS.
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Affiliation(s)
- Chan Hee Moon
- Department of Ophthalmology, Soonchunhyang University College of Medicine, Bucheon Hospital, #1174 Jung-dong, Wonmi-gu, Bucheon 420-767, South Korea
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Wen Y, Klein M, Hood DC, Birch DG. Relationships among multifocal electroretinogram amplitude, visual field sensitivity, and SD-OCT receptor layer thicknesses in patients with retinitis pigmentosa. Invest Ophthalmol Vis Sci 2012; 53:833-40. [PMID: 22247460 DOI: 10.1167/iovs.11-8410] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To compare local functional measures, the multifocal electroretinogram (mfERG) and visual field sensitivity, with a local structural measure, spectral domain (SD) optical coherence tomography (OCT), of receptor damage in patients with retinitis pigmentosa (RP). METHODS MfERGs, visual fields, and SD-OCT scans were obtained from 10 patients with RP, ranging in age from 23 to 59 years. Average amplitudes, average linear sensitivities, and average layer thicknesses were measured from within the central 3° and from three concentric annuli located between 3° and 8°, 8° and 15°, and 15° and 24°. A computer program aided manual segmentation and calculated OCT thickness in the scans. RESULTS Within each patient with RP, mfERG amplitude for each circle/annulus was highly correlated with corresponding layer thicknesses in the outer retina (r = 0.88 to 0.99), but not at all correlated with thickness of the inner nuclear layer or total retina. Across all ring eccentricities, relative mfERG amplitude and relative visual field sensitivity were correlated with relative SD-OCT outer retinal thickness. CONCLUSIONS In patients with RP, preserved cone photoreceptor function measured by mfERG amplitude and visual field sensitivity correlate well with the remaining thickness of the photoreceptor layer. All three measures show comparable relative loss beyond 3° eccentricity. In the fovea, SD-OCT outer retina thickness showed less relative loss than either mfERG or visual field sensitivity.
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Affiliation(s)
- Yuquan Wen
- Retina Foundation of the Southwest, Dallas, Texas, USA.
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Maiti A, Uparkar M, Natarajan S, Borse N, Walinjkar J. Principal components' analysis of multifocal electroretinogram in retinitis pigmentosa. Indian J Ophthalmol 2012; 59:353-7. [PMID: 21836339 PMCID: PMC3159315 DOI: 10.4103/0301-4738.83610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
AIMS To determine waveforms of multifocal electroretinogram (mfERG) in patients with retinitis pigmentosa (RP) contributing significantly to the overall retinal response by using principal components' analysis. SETTINGS AND DESIGN Prospective, non-randomized, single-visit, observational, case-control study from a single tertiary ophthalmic center. MATERIALS AND METHODS Patients with various forms of RP underwent mfERG testing for a period of one year. The first-order kernel responses of RP cases were compared with concurrently recruited healthy controls. STATISTICAL ANALYSIS USED Parametric data was analyzed using the unpaired t test for differences between the implicit time and amplitudes of cases and controls. Principal components' analysis was done for each implicit time and amplitude in cases with RP using the Varimax rotation method. RESULTS From March 2006 to March 2007, 24 cases with typical RP (56%, 47 eyes) were included in the final analysis. Their mean age was 33.7 years (19-69 ± 15.5 years). Comparison of latencies and amplitudes among RP cases with log MAR acuity ≤ 0.18 and those > 0.18, revealed significant difference in the implicit time (P1) in Ring 2 only (P=0.028). Two components (predominently from Ring 1 and 2) each contributing 66.8% and 88.8% of the total variance in the data for latencies and amplitudes respectively, were seen. CONCLUSIONS The first two rings of the mfERG contributed to the variance of waveforms in RP, irrespective of the visual acuity and poor visual field results.
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Affiliation(s)
- Aniruddha Maiti
- Department of Vitreo-Retinal Services, Aditya Jyot Eye Hospital Pvt Ltd, Plot No: 153, Road No 9, Major Parmeswaran Road, Wadala, Mumbai - 400 031, India.
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Park JY, Kim SH, Park TK, Ohn YH. Multifocal electroretinogram findings after intravitreal bevacizumab injection in choroidal neovascularization of age-related macular degeneration. Korean J Ophthalmol 2011; 25:161-5. [PMID: 21655040 PMCID: PMC3102818 DOI: 10.3341/kjo.2011.25.3.161] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 10/02/2010] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To evaluate the changes in multifocal electroretinogram (mfERG) and optical coherence tomography (OCT) after intravitreal bevacizumab injection in the treatment of age-related macular degeneration (AMD). METHODS Twenty-one eyes with choroidal neovascularization secondary to AMD were studied before and after intravitreal bevacizumab injection for best corrected visual acuity (BCVA), OCT, and mfERG. RESULTS The BCVA improved, while central macular thickness and total macular volume in OCT decreased after intravitreal bevacizumab injection (p = 0.03, 0.01, and 0.01, respectively). In mfERG, the amplitude of P1, and implicit time of P1 and N1 indicated a statistically significant improvement of retinal response after intravitreal bevacizumab injection. CONCLUSIONS There is a potential role for mfERG in evaluating the effect on retinal function of intravitreal bevacizumab injection.
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Affiliation(s)
- Joo Youn Park
- Department of Ophthalmology, Soonchunhyang University College of Medicine, Bucheon, Korea
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Parisi V, Ziccardi L, Stifano G, Montrone L, Gallinaro G, Falsini B. Impact of regional retinal responses on cortical visually evoked responses: multifocal ERGs and VEPs in the retinitis pigmentosa model. Clin Neurophysiol 2010; 121:380-5. [PMID: 20071230 DOI: 10.1016/j.clinph.2009.09.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2009] [Revised: 09/22/2009] [Accepted: 09/28/2009] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine the impact of the regional retinal responses on cortical visually evoked responses, by evaluating the relationship between multifocal ERG (mfERG) and multifocal VEP (mfVEP), in the retinitis pigmentosa (RP) model. METHODS MfERGs and mfVEPs were recorded from 20 typical RP patients. Response amplitude density (RAD, nV/deg(2)) and implicit time (ms) of the mfERG 1st order binary kernel (N1-P1) and mfVEP 2nd order binary kernel (P1) components were measured. Ring analysis, matched for mfERG and mfVEP stimuli, was performed between fovea and mid-periphery (0-2.5, 2.5-5, 5-10, 10-15 and 15-20deg). RESULTS At central and pericentral retinal regions (four eccentricities between 0 and 15deg), mfERG N1 RADs were positively correlated (r0.68, p<0.01) with corresponding mfVEP P1 RADs. Similarly, mfERG P1 implicit times were positively correlated (r>or=0.65, p<0.01) with corresponding mfVEP N1 implicit times. CONCLUSIONS There are quantitative correlations between mfERG and mfVEP components in RP. SIGNIFICANCE The data suggest that regional responses of the photoreceptors and off-bipolar cells, the main generators of mfERG N1, have a major impact on the corresponding cortical activity.
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Affiliation(s)
- Vincenzo Parisi
- Fondazione G.B. Bietti, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
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Abstract
Usher syndrome denotes a clinically and genetically heterogeneous combination of retinitis pigmentosa and sensorineural deafness. The division into subtypes I, II, and III is based on the degree of hearing loss: Type I is characterized by deafness from birth together with ataxia and retarded motor development, type II by a stationary deafness of a moderate degree, and type III by a progressive deafness with adult onset. In Germany, Usher syndrome currently bears particular relevance because in January 2009 a new compulsory screening of auditory function in newborn infants was introduced. Consequently, it can be expected that a higher number of patients with Usher syndrome will be identified in early childhood and referred to ophthalmologists. The focus of this work is to introduce the typical clinical picture of Usher syndrome, summarize diagnostic options, and give an overview of therapeutic strategies.
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Affiliation(s)
- Sun Young Jang
- Department of Ophthalmology, Soonchunhyang University, College of Medicine, Bucheon, Korea
| | - Sang Hyun Lim
- Department of Ophthalmology, University of California at San Francisco, Cornea Service, California, USA
| | - Young-Hoon Ohn
- Department of Ophthalmology, Soonchunhyang University, College of Medicine, Bucheon, Korea
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Wolsley CJ, Silvestri G, O'Neill J, Saunders KJ, Anderson RS. The association between multifocal electroretinograms and OCT retinal thickness in retinitis pigmentosa patients with good visual acuity. Eye (Lond) 2008; 23:1524-31. [PMID: 18978727 DOI: 10.1038/eye.2008.318] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AIMS To investigate relationships between retinal morphology and retinal function in patients with retinitis pigmentosa (RP) using optical coherence tomography (OCT) and multifocal electroretinography (mfERG). METHODS In all, 14 patients with RP who had visual acuities of 0.2 logMAR or better and Humphrey central fields of 10 degrees or larger participated in the study along with 16 normal control subjects. The amplitudes and timings of the mfERG responses were compared with spatially corresponding measures of retinal layer thickness from OCT within the macula region (central 12 degrees ). RESULTS Eyes with RP showed thinning of the photoreceptor retinal (PR) layer and thickening of mid-inner retinal (MIR) layers beyond the fovea. mfERG amplitude was reduced in all regions, whereas mfERG timing was only significantly delayed at a retinal eccentricity of 6-12 degrees and was otherwise preserved within the foveal and parafoveal retina (0-6 degrees). PR layer thickness was correlated with mfERG amplitude across the macula region. mfERG timing was correlated with the total change in retinal thickness (combined PR thinning and MIR thickening) at an eccentricity of 6-12 degrees. CONCLUSIONS The relationship between mfERG timing and retinal thickness in RP is dependent on the retinal eccentricity. Preserved timing in the central retina (0-6 degrees ), despite significant disruption to retinal laminar structure, could be suggestive of inner retinal remodelling or functional redundancy. Cone system activity derived from mfERG amplitude appears to be related to the thickness of the photoreceptor layer in the macula region.
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Affiliation(s)
- C J Wolsley
- Vision Science Research Group, Department of Optometry, University of Ulster, Coleraine, UK.
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Janáky M, Pálffy A, Horváth G, Tuboly G, Benedek G. Pattern-reversal electroretinograms and visual evoked potentials in retinitis pigmentosa. Doc Ophthalmol 2007; 117:27-36. [PMID: 18034272 DOI: 10.1007/s10633-007-9099-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Accepted: 10/31/2007] [Indexed: 11/29/2022]
Affiliation(s)
- Márta Janáky
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, Korányi rkpt. 10-11, Pf: 427, 6720 Szeged, Hungary.
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Abstract
Multifocal electroretinography (mfERG) is an investigation that can simultaneously measure multiple electroretinographic responses at different retinal locations by cross-correlation techniques. mfERG therefore allows topographic mapping of retinal function in the central 40-50 degrees of the retina. The strength of mfERG lies in its ability to provide objective assessment of the central retinal function at different retinal areas within a short duration of time. Since the introduction of mfERG in 1992, mfERG has been applied in a large variety of clinical settings. This article reviews the clinical applications of mfERG based on the currently available evidence. mfERG has been found to be useful in the assessment of localized retinal dysfunction caused by various acquired or hereditary retinal disorders. The use of mfERG also enabled clinicians to objectively monitor the treatment outcomes as the changes in visual functions might not be reflected by subjective methods of assessment. By changing the stimulus, recording, and analysis parameters, investigation of specific retinal electrophysiological components can be performed topographically. Further developments and consolidations of these parameters will likely broaden the use of mfERG in the clinical setting.
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Affiliation(s)
- Timothy Y Y Lai
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, People's Republic of China
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18
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Neveu MM, Tufail A, Dowler JG, Holder GE. A comparison of pattern and multifocal electroretinography in the evaluation of age-related macular degeneration and its treatment with photodynamic therapy. Doc Ophthalmol 2006; 113:71-81. [PMID: 16972084 DOI: 10.1007/s10633-006-9016-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Indexed: 10/24/2022]
Abstract
This study compares pattern electroretinography (PERG) and multifocal electroretinography (mfERG) measures in 13 patients with predominantly classic choroidal neovascularisation (CNV) associated with age-related macular degeneration (ARMD, 9/13 unilateral, 4/13 bilateral), assesses the usefulness of each test in monitoring disease progression, and identifies electrophysiological predictors of outcome following treatment with photodynamic therapy (PDT). PERG and mfERGs were recorded at presentation, 2 weeks post-treatment, and at 3 monthly intervals for 2 years. The PERG was detectable in 8/13 patients with unilateral disease; the mfERG was detectable in 12/13 patients. P50 and N95 amplitudes increased in 6/8 patients and mfERG p1 increased in 7/13 patients at 2 years. PERG amplitudes correlated strongly with mfERG amplitudes in patients with unilateral disease. PERG P50 and mfERG p1 amplitude correlated with visual acuity at 2 years (R = 0.68, R = 0.82, respectively). The largest PERG P50 and mfERG p1 amplitude difference between treated and fellow eyes of all the groups on initial visit was associated with a poor visual outcome (P50 64% difference; p1 29% difference) whereas those with the smallest P50 and p1 amplitude difference was associated with improved vision at 2 years (P50 30% difference; p1 21% difference). The PERG and mfERG provide an objective measure of central retinal function in the progression of ARMD. A detectable PERG on presentation was the single best indicator of improved function and visual acuity at 2 years. The mfERG demonstrated disease progression from central retina into the paramacular regions over 2 years. Patients with poor visual outcomes had the largest inter-ocular amplitude difference on presentation, suggesting that such patients may have a worse prognosis following treatment.
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Bearse MA, Adams AJ, Han Y, Schneck ME, Ng J, Bronson-Castain K, Barez S. A multifocal electroretinogram model predicting the development of diabetic retinopathy. Prog Retin Eye Res 2006; 25:425-48. [PMID: 16949855 PMCID: PMC2773701 DOI: 10.1016/j.preteyeres.2006.07.001] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The prevalence of diabetes has been accelerating at an alarming rate in the last decade; some describe it as an epidemic. Diabetic eye complications are the leading cause of blindness in adults aged 25-74 in the United States. Early diagnosis and development of effective preventatives and treatments of diabetic retinopathy are essential to save sight. We describe efforts to establish functional indicators of retinal health and predictors of diabetic retinopathy. These indicators and predictors will be needed as markers of the efficacy of new therapies. Clinical trials aimed at either prevention or early treatments will rely heavily on the discovery of sensitive methods to identify patients and retinal locations at risk, as well as to evaluate treatment effects. We report on recent success in revealing local functional changes of the retina with the multifocal electroretinogram (mfERG). This objective measure allows the simultaneous recording of responses from over 100 small retinal patches across the central 45 degrees field. We describe the sensitivity of mfERG implicit time measurement for revealing functional alterations of the retina in diabetes, the local correspondence between functional (mfERG) and structural (vascular) abnormalities in eyes with early nonproliferative retinopathy, and longitudinal studies to formulate models to predict the retinal sites of future retinopathic signs. A multivariate model including mfERG implicit time delays and 'person' risk factors achieved 86% sensitivity and 84% specificity for prediction of new retinopathy development over one year at specific locations in eyes with some retinopathy at baseline. A preliminary test of the model yielded very positive results. This model appears to be the first to predict, quantitatively, the retinal locations of new nonproliferative diabetic retinopathy development over a one-year period. In a separate study, the predictive power of a model was assessed over one- and two-year follow-ups. This permitted successful prediction of new retinopathy development in eyes with and without retinopathy at baseline. Finally, we briefly describe our current research efforts to (a) locally predict future sight-threatening diabetic macular edema, (b) investigate local retinal function change in adolescent patients with diabetes, and (c) better understand the physiological bases of the mfERG delays. The ability to predict the retinal locations of future retinopathy based on mfERG implicit time provides clinicians a powerful tool to screen, follow-up, and even consider early prophylactic treatment of the retinal tissue in diabetic patients. It also aids identification of 'at risk' populations for clinical trials of candidate therapies, which may greatly reduce their cost by decreasing the size of the needed sample and the duration of the trial.
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Affiliation(s)
- Marcus A Bearse
- School of Optometry and Vision Science Program, University of California, Berkeley, Berkeley, CA 94720-2020, USA
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20
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Chu PHW, Chan HHL, Leat SJ. Effects of unsteady fixation on multifocal electroretinogram (mfERG). Graefes Arch Clin Exp Ophthalmol 2006; 244:1273-82. [PMID: 16550403 DOI: 10.1007/s00417-006-0304-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 02/02/2006] [Accepted: 02/04/2006] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To investigate the effect of unsteady fixation on the multifocal electroretinogram (mfERG) measurement in normal subjects. METHODS The mfERGs of 20 subjects with normal vision (mean age=23.5 years) were recorded with different levels of voluntary eye movements made to mimic unsteady fixation. Subjects were required to move their fixation regularly every 2 s between the center and the ends of a fixation cross, so that 51.2% of the time fixation was at the center and 12.2% of the time it was at each end of the fixation cross. Four different conditions were performed: central fixation (without voluntary eye movements) and with 2 degrees, 4 degrees and 6 degrees magnitude of unsteady fixation. First-order kernel mfERG findings are presented. RESULTS Analysis of the ring responses indicated that the central mfERG amplitude was most affected by unsteady fixation. There was significantly reduced amplitude for 4 degrees unsteady fixation and as expected, this reduction became larger with 6 degrees unstable fixation. However, there was no significant effect on the center hexagon amplitude for 2 degrees unsteady fixation. The amplitudes of the ring-2 responses were only affected in the 6 degrees unsteady fixation condition. No significant change in implicit time was found for any level of unsteady fixation. CONCLUSION These results suggest that mfERG amplitude is not substantially affected if fixation is maintained within the central stimulus hexagon. We conclude that, for patients with poor fixation, the accuracy of mfERG results may be difficult to interpret and the use of a fixation-monitoring system is desirable for ideal measurement. The depth of depression at the blind spot area may be another useful parameter to interpret the accuracy of mfERG results in patients with poor fixation.
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Affiliation(s)
- Patrick H W Chu
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR, People's Republic of China
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21
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Holopigian K, Shuwairi SM, Greenstein VC, Winn BJ, Zhang X, Carr RE, Hood DC. Multifocal visual evoked potentials to cone specific stimuli in patients with retinitis pigmentosa. Vision Res 2005; 45:3244-52. [PMID: 16023698 DOI: 10.1016/j.visres.2005.05.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 05/13/2005] [Accepted: 05/17/2005] [Indexed: 10/25/2022]
Abstract
Our aim was to determine whether patients with retinitis pigmentosa show differences in L- and M-cone multifocal visual evoked potential (mfVEP) responses that are eccentricity dependent, as has been shown for control subjects. Second, we compared the losses for mfVEPs to losses on achromatic visual field and multifocal electroretinogram (mfERG) measures in the patients. Monocular mfVEPs were recorded to a pattern reversing display that modulated only the L- or M-cones. Also, standard automated achromatic visual fields and mfERGs were obtained. For the control subjects, the ratio of L-cone to M-cone mfVEP amplitudes increased as a function of retinal eccentricity. For the patients, the ratio did not vary with eccentricity. For all measures, responses were least affected for the first ring (central 2.4 degrees ) and most affected for the third ring (11.6 degrees - 44.4 degrees ). For the first ring, mfERG amplitudes were more impaired than were the mfVEPs or the visual field thresholds. For most of the patients, there was local response correspondence among our measures of visual function.
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Affiliation(s)
- K Holopigian
- Department of Ophthalmology, New York University School of Medicine, BEL 5N15, 462 First Avenue, New York, NY 10016, USA.
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Seiple W, Clemens CJ, Greenstein VC, Carr RE, Holopigian K. Test-retest reliability of the multifocal electroretinogram and humphrey visual fields in patients with retinitis pigmentosa. Doc Ophthalmol 2005; 109:255-72. [PMID: 15957611 DOI: 10.1007/s10633-005-0567-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We examined the reliability of Humphrey visual field thresholds and multifocal electroretinogram (mfERG) amplitudes and timing in a group of patients with Retinitis Pigmentosa (RP). Eight patients with RP and seven control subjects were tested five times: at baseline (visit #0), at three weekly follow-up visits (visits #1 - #3), and at three months (visit #4). For the Humphrey thresholds, differences between dB values on repeat visits were obtained. Differences between log values on repeat visits were calculated for mfERG amplitude and implicit time. We used the standard deviations of these difference scores as a measure of reliability and the means of the difference scores as a measure of progression. We found that the majority of the patients' repeat data were more variable than that of the control subjects for both the Humphrey and mfERG. We found no single factor that predicted the magnitude, or the variance, of the SD of differences scores for the patients. We recommend that each patient's reliability be assessed individually. Ultimately, the choice of an outcome measure must be guided by its reliability, as well as its ability to assess the visual function of interest.
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Affiliation(s)
- William Seiple
- Department of Ophthalmology, New York University School of Medicine, NB-5N15, 550 First Ave, New York, NY 10016, USA.
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23
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Abstract
The co-occurrence of ophthalmologic abnormality and intrinsic skeletal dysplasia is uncommon. We describe eight instances of a unique form of spondylometaphyseal dysplasia (SMD) associated with cone-rod dystrophy (although documentation is insufficient to be certain of that diagnosis in some). This is a new, syndromic form of SMD for which there is evidence for autosomal recessive transmission. Recognition of the specific bony features described here should precipitate comprehensive ophthalmologic assessment, since vision impairment becomes significantly disabling with age.
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Affiliation(s)
- Brent A Walters
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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24
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Greenstein VC, Holopigian K, Seiple W, Carr RE, Hood DC. Atypical multifocal ERG responses in patients with diseases affecting the photoreceptors. Vision Res 2005; 44:2867-74. [PMID: 15380992 DOI: 10.1016/j.visres.2004.06.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Revised: 06/14/2004] [Indexed: 12/01/2022]
Abstract
The purpose of this study was to investigate atypical multifocal ERG (mfERG) responses for patients with diseases that can affect the photoreceptors. MfERGS were obtained from seven patients with retinitis pigmentosa (RP), three with progressive cone dystrophy (CD) and eight with diabetic retinopathy (DR). Both first- and second-order kernel responses were analyzed. The amplitudes and implicit times of the first-order responses were compared to those obtained from age-similar controls. For the first slice of the second-order response, the root-mean-square (RMS) and the signal-to-noise ratio (SNR) of each response were calculated. Achromatic visual fields were also obtained from each subject. For the three groups of patients, first-order responses with relatively large amplitudes, broad-shaped waveforms and markedly increased implicit times had non-measurable second-order responses. These responses were associated with areas of decreased visual field sensitivity. As RP, CD and DR affect the outer retina, the results are consistent with damage to the outer plexiform layer rather than damage to the inner retina.
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Affiliation(s)
- V C Greenstein
- Department of Ophthalmology, College of Physicians and Surgeons, Edwards S. Harkness Eye Institute, Columbia University, 635 West 165th Street, New York, NY 10032, USA.
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Schneck ME, Bearse MA, Han Y, Barez S, Jacobsen C, Adams AJ. Comparison of mfERG waveform components and implicit time measurement techniques for detecting functional change in early diabetic eye disease. Doc Ophthalmol 2005; 108:223-30. [PMID: 15573946 DOI: 10.1007/s10633-004-8745-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study first compares two methods for measuring first order multifocal electroretinogram (mfERG) implicit time abnormalities in eyes with early diabetic retinopathy. Two analysis methods are used: template stretching (multiplicative scaling) of an 80 msec response epoch and template sliding (cross-correlation or additive scaling) of portions of responses containing the major waveform features. The study also compares the relative sensitivities of N1, P1 and N2 implicit time assessed by cross-correlation. The nature of the change in the mfERG waveform associated with diabetes is also assessed. MfERGs were recorded from 15 eyes of 15 individuals with diabetes and early non-proliferative retinopathy and 20 eyes of 20 healthy control subjects of similar age. Implicit time determined by template stretching is more frequently abnormal in the eyes of the diabetic subjects than the implicit time of any of the components assessed by template sliding. This is attributable to the lower variability of the template stretching implicit time measure in normals. Of the components, P1 is most often abnormal in the eyes of individuals with diabetes. Responses recorded from retinal areas with retinopathic signs are more often abnormal than those from other areas. Later components of the response are not delayed more than earlier ones. We conclude that template stretching is a sensitive measurement technique, but that it does not fully capture the effect of diabetes on the first order mfERG well.
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Affiliation(s)
- Marilyn E Schneck
- Vision Sciences Program, School of Optometry, University of California at Berkeley, Berkeley, CA 94720-2020, USA.
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26
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Feigl B. Das multifokale Elektroretinogramm in der altersabhängigen Makulopathie. Spektrum Augenheilkd 2004. [DOI: 10.1007/bf03163598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
PURPOSE To investigate the cone- and rod-mediated multifocal electroretinograms (mfERG) in early age-related maculopathy (early ARM). METHODS AND SUBJECTS We investigated the cone- and rod-mediated mfERG in 17 eyes of 17 subjects with early ARM and 16 eyes of 16 age-matched control subjects with normal fundi. All subjects had a visual acuity of 6/12 or better. We divided the ARM subjects into two groups based on drusen size and retinal pigment epithelium abnormalities-a less advanced (ARM1) and a more advanced (ARM2) group. The mfERG data were compared to templates derived from the control group. We analysed the mfERG results for the central and peripheral fields (CP method) and the superior and inferior fields (SI method). RESULTS While the mean cone results showed no statistically significant difference between the groups, the rods showed significantly delayed responses in the ARM1 group for the CP and the SI methods, but not in the ARM2 group, although there was a trend of longer latencies compared to the control group. CONCLUSION Our results show a functional impairment of the rods in early ARM subjects. As there is histopathological evidence showing earlier rod than cone impairment in early ARM, following the rod function with the mfERG might be helpful in diagnosis or for monitoring the progression of early ARM.
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Affiliation(s)
- B Feigl
- Department of Ophthalmology, University of Graz, Austria.
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Kondo M, Miyake Y, Kondo N, Ueno S, Takakuwa H, Terasaki H. Peripheral cone dystrophy*1A variant of cone dystrophy with predominant dysfunction in the peripheral cone system1. Ophthalmology 2004; 111:732-9. [PMID: 15051206 DOI: 10.1016/j.ophtha.2003.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2002] [Accepted: 07/30/2003] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To determine the phenotype of 3 patients from 2 pedigrees with an unusual form of cone dystrophy in which the peripheral cone system is more affected than the central cone system, and whose rod system is relatively normal. DESIGN Three observational case reports with electrophysiologic and psychophysical studies. METHODS Three patients underwent fundus photography, fluorescein angiography, color vision testing, Goldmann visual field testing, full-field electroretinograms (ERGs), focal macular cone ERGs, and rod-cone perimetry, in addition to routine ophthalmologic examinations. Multifocal ERGs also were recorded from 2 patients. RESULTS The fundus examination and fluorescein angiogram results essentially were normal except for a mild temporal pallor of the optic disc in 2 patients. The corrected visual acuity ranged from 20/16 to 20/100. Color vision was normal in 1 patient, but was abnormal in 2 patients. A relative paracentral scotoma was detected in 2 patients. Full-field ERG cone responses were reduced significantly, but rod responses were normal in all patients, as in patients with typical cone dystrophy. However, the focal macular cone ERGs were well preserved in all patients. Psychophysical rod-cone perimetry demonstrated that the peripheral cone system was impaired, whereas the rod sensitivity was completely normal. The results of the multifocal ERG in 2 patients supported the findings made by the full-field and focal macular ERGs. CONCLUSIONS These findings demonstrate that there is a subgroup of patients with cone dystrophy where the peripheral cone system is more affected than the central cone system.
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Affiliation(s)
- Mineo Kondo
- Department of Ophthalmology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.
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Jiang L, Jin C, Wen F, Huang S, Wu D, Wu L. The changes of multifocal electroretinography in the early stage of photodynamic therapy for choroidal neovascularization. Doc Ophthalmol 2004; 107:165-70. [PMID: 14661906 DOI: 10.1023/a:1026215221569] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To investigate short-term changes in the multifocal electroretinography (ERG) recordings after photodynamic therapy (PDT) for choroidal neovascularization (CNV), 16 patients (17 eyes) with classic CNV confirmed by fluorescein angiography (FA) and indocyanine green angiography (ICGA), including 11 cases (12 eyes) of exudative age-related macular degeneration (AMD), two cases (two eyes) of pathological myopia and three cases (three eyes) of idiopathic causes, were treated using PDT with verteporfin. The multifocal ERGs of these patients were tested with VERIS Science 4.0 imaging system. The latencies and average response densities of all six ring retinal regions were measured and compared before PDT and 3 or 7 days after PDT. The latencies and amplitude densities of the N1 and P1 waves in all six rings remained unchanged at 3 or 7 days post-treatment (p > 0.05). Therefore, there is no significant evidence to suggest an adverse effect from PDT for classic CNV on the outer retinal function in the early stage of treatment, with the aid of the multifocal ERG recordings.
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Affiliation(s)
- Libin Jiang
- Department of Ophthalmology, Beijing Tongren Hospital, Capital University of Medical Sciences, Beijing, 100730, China.
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30
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Abstract
The multifocal electroretinogram (mfERG) technique allows local ERG responses to be recorded simultaneously from many regions of the retina. As in the case of the full-field ERG, the ganglion cells contribute relatively little to the response, which originates largely from the outer retina. The mfERG is particularly valuable in cases in which the fundus appears normal, and it is difficult to distinguish between diseases of the outer retina and diseases of the ganglion cells and/or optic nerve. The mfERG can also help to differentiate among outer retinal diseases, to follow the progression of retinal diseases, and, with the addition of the mfVEP, to differentiate between organic and nonorganic causes of visual loss. However, because the difficulties encountered in recording and analyzing mfERG responses are greater than those involved in full-field ERG testing, mfERG testing is best left to centers with an electrophysiologist familiar with the mfERG test. Although this technique is relatively new and standards are still being developed, centers capable of recording reliable mfERG responses can be found in hundreds of locations around the world.
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Affiliation(s)
- Donald C Hood
- Department of Psychology, 405 Schermerhorn, Columbia University, New York, NY 10027, USA
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31
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Rudolph G, Kalpadakis P, Bechmann M, Haritoglou C, Kampik A. Scanning laser ophthalmoscope-evoked multifocal ERG (SLO-mfERG) in patients with macular holes and normal individuals. Eye (Lond) 2003; 17:801-8. [PMID: 14528241 DOI: 10.1038/sj.eye.6700502] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIMS A scanning laser ophthalmoscope (SLO) has been used for multifocal electroretinography (mf ERG) measurements under simultaneous fundus monitoring. The aim of this study was to prove if the SLO-mfERG measurement reflects reliably the clinically registered underlying disease, and to demonstrate the importance of its main advantage, fixation monitoring. METHODS In all, 10 patients with macular hole stage II/III were included in the study, and 19 normal individuals served as the control group. The mf ERG device was combined with an SLO, which was used both as a stimulus and trigger unit as well as a fundus-monitoring system. Monitoring of the fundus was guaranteed by an infrared laser (780 nm). The stimulus matrix consisted of 61 hexagonal elements, covering 24 degrees of the posterior pole. We examined both, patients with macular holes and healthy individuals. RESULTS Compared to normal controls, patients with a macular hole (Gass stage III) showed a significant decrease in response density in the centre of the stimulus array, which correlated well with the morphological alteration observed by clinical examination. However, variation of response density of the central hexagonal area has been proved to be high. CONCLUSIONS SLO-mfERG is a feasible and reliable new technique to investigate macular function under simultaneous fundus control. The main advantage is that control of fixation can be used in order to obtain more reliable results that correlate well with visible fundus abnormalities such as in patients with macular holes. However, further investigations have to be performed in order to overcome sufficiently the problem of fixation instability.
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Affiliation(s)
- G Rudolph
- Eye Clinic, Ludwig-Maximilians-University Munich, Germany.
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Seeliger MW, Weber BHF, Besch D, Zrenner E, Schrewe H, Mayser H. MfERG waveform characteristics in the RS1h mouse model featuring a 'negative' ERG. Doc Ophthalmol 2003; 107:37-44. [PMID: 12906120 DOI: 10.1023/a:1024496130538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several retinal disorders lead to a relatively greater attenuation of the b-wave compared to the a-wave of the electroretinogram (ERG), a constellation called 'negative' ERG. To determine the waveform characteristics of multifocal ERGs (mfERGs) and their dependence on recording parameters in such a case, we studied the Rs1h(-/Y) mouse, the model for x-linked juvenile retinoschisis. mfERGs were recorded with a VERIS 4 system connected to a piggyback stimulator prototype that added the stimulus to the optical pathway of a HRA scanning-laser ophthalmoscope (SLO) by means of a wavelength-sensitive mirror. Real-time fundus visualization was achieved with the infrared laser of the SLO (835 nm). High-pass filter settings and the time interval used by the 'artefact removal' feature were varied to study their influence on the waveform. The mfERG in the Rs1h(-/Y) mouse had a 'negative' shape. However, the high-pass filter setting had to be lowered from the usual 10 Hz down to about 2 Hz in order to obtain that result, otherwise the negative shape was lost and mainly a positive peak remained. Similarly, a short time interval used by the 'artefact removal' feature also removed the negative shape. The Rs1h(-/Y) mouse was found to be a valuable model of diseases with a 'negative' waveform shape also in mfERG. Our results underline the importance of a lower high-pass filter cutoff frequency when recording mfERGs in such disorders. In addition, if the 'artefact removal' feature is used, it should be verified that it doesn't distort the waveform shape.
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Affiliation(s)
- Mathias W Seeliger
- Retinal Electrodiagnostics Research Group, University Eye Hospital Department II, Schleichstr. 12-16, D-72076 Tübingen, Germany.
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33
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Abstract
Visual acuity is an essential component of the routine ophthalmic examination and the most common measure of visual function. There is increasing recognition, however, of the need to evaluate visual function beyond the limited extent afforded by visual acuity. The primary objective of this article is to introduce a variety of new and lesser-used techniques for measuring visual function that complement visual acuity assessment, each of which has been shown to detect visual dysfunction in patients with normal visual acuity.
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Affiliation(s)
- Gary L Trick
- Visual Diagnostic Service, Department of Eye Care Services, Henry Ford Health Center, 2799 West Grand Boulevard, Detroit, MI 48202, USA.
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34
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Abstract
The purpose was to study long- (L-) and middle-wavelength-sensitive (M-) cone-driven ERGs and multifocal ERGs (mfERGs) in sector retinitis pigmentosa (sector RP). Two eyes of two patients with sector RP were measured. ERG responses were measured to stimuli which modulated exclusively the L- or the M-cones or the two simultaneously (both in-phase and in counter-phase) with predefined cone contrast leaving the S-cones unmodulated. For comparison, mfERGs were recorded with the visual evoked response imaging system, using a resolution of 61 hexagonal elements within a 30-degree visual field. The two sector RP patients exhibited a general reduction of the L-/M-cone driven ERG sensitivity. Patient 1 exhibited a slight delay of the M-cone driven ERG. In patient 2, L-cone driven ERG was moderately delayed. In both patients, the phases of the L- and the M-cone driven ERGs were positively correlated with cone contrast. The data of the L/M-cone driven ERGs, the mfERGs and the standard photopic ERGs matched each other qualitatively. We conclude that the sector RP patients were clearly different from normal for both the L- and M-cone driven large-field and the multifocal ERGs. Previously, we investigated L- and M-cone driven ERGs in patients with generalized RP and found several features that differ from the sector RP patients. Our data are in agreement with our previous proposition that amplitudes and phases of the L- and M-cone driven ERGs can be differently affected by retinal disorders.
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Affiliation(s)
- Hendrik P N Scholl
- Department of Experimental Ophthalmology, University Eye Hospital, Tübingen, Germany
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35
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Poloschek CM, Rupp V, Krastel H, Holz FG. Multifocal ERG recording with simultaneous fundus monitoring using a confocal scanning laser ophthalmoscope. Eye (Lond) 2003; 17:159-66. [PMID: 12640401 DOI: 10.1038/sj.eye.6700294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To assess the general feasibility of recording multifocal electroretinograms (mfERGs) with simultaneous fundus monitoring in a clinical setting. METHODS An mfERG system (RETIscan) and a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph) were connected to record mfERGs elicited by a pseudorandom binary m-sequence stimulus generated by a 514 nm laser source. Recordings were compared to a conventional mfERG system using monitor stimulation. A total of five subjects (two normal subjects and three patients) were examined. RESULTS In normal volunteers records obtained by the fundus-monitored mfERG showed highest response densities in the central fundus area and a decrease of response amplitudes towards the periphery paralleling cone receptor density. However, compared to the monitor stimulation, the drop-off of amplitudes as a function of eccentricity was not as clearly defined. The responses obtained from patients with retinal diseases were diminished in the areas of retinal dysfunction. CONCLUSIONS These preliminary findings indicate that the technique of laser stimulation in principle allows for topographic retinal recording. This method might be useful, for example if the retinal position of the stimulus array is not centred onto the fovea but deviates due to fixation problems. However, further improvement of the technique appears necessary before considering routine clinical application.
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Affiliation(s)
- C M Poloschek
- Department of Ophthamology, University of Heidelberg, Germany
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36
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Dolan FM, Parks S, Hammer H, Keating D. The wide field multifocal electroretinogram reveals retinal dysfunction in early retinitis pigmentosa. Br J Ophthalmol 2002; 86:480-1. [PMID: 11914231 PMCID: PMC1771092 DOI: 10.1136/bjo.86.4.480] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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37
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Dietrich K, Jacobi FK, Tippmann S, Schmid R, Zrenner E, Wissinger B, Apfelstedt-Sylla E. A novel mutation of the RP1 gene (Lys778ter) associated with autosomal dominant retinitis pigmentosa. Br J Ophthalmol 2002; 86:328-32. [PMID: 11864893 PMCID: PMC1771063 DOI: 10.1136/bjo.86.3.328] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Besides the three known genes (RHO, RDS/Peripherin, NRL) involved in autosomal dominant retinitis pigmentosa (adRP), a fourth gene, RP1, has been recently identified. Initial reports suggest that mutations in the RP1 gene are the second most frequent cause of adRP. The clinical findings were described in a family with adRP and a novel mutation in the RP1 gene. METHOD Index patients from 15 independent families with adRP in which RHO mutations had been excluded in previous examinations were screened for mutations in the RP1 gene by means of direct DNA sequencing. Evaluation of the RP1 phenotype in patients included funduscopy, kinetic perimetry, dark adapted final threshold test, standard electroretinography and, in one case, multifocal electroretinography. RESULTS One novel nonsense mutation (Lys778ter) in one of these 15 patients was detected. Cosegregation of the mutation with the disease phenotype could be established in the index patient's family. The phenotype comprises variable expression of clinical disease probably including one case of incomplete penetrance, a onset of symptoms beginning in adulthood, and evidence of regionally varying retinal function loss. CONCLUSION The Lys778ter mutation localises inside the critical region harbouring all mutations described so far. The ophthalmic findings support previous observations that variation of disease expression appears as a typical feature of the RP1 phenotype.
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Affiliation(s)
- K Dietrich
- Molekulargenetisches Labor, Universitäts-Augenklinik, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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38
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Eksandh L, Ekström U, Abrahamson M, Bauer B, Andréasson S. Different clinical expressions in two families with Stargardt's macular dystrophy (STGD1). Acta Ophthalmol Scand 2001; 79:524-30. [PMID: 11594993 DOI: 10.1034/j.1600-0420.2001.790520.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE To describe the clinical expressions, with emphasis on electrophysiological examinations, in two Swedish families with Stargardt's macular dystrophy (STGD1). METHODS Two pairs of siblings with STGD1, for whom diagnosis had been confirmed by genetic linkage to the ABCA4 gene region, were examined regarding visual acuity, kinetic perimetry, fundus photography, full-field ERG and multifocal ERG (MERG). Possible disease-causing mutations were screened for by DNA sequencing of selected regions of the ABCA4 gene. RESULTS All STGD1 patients had visual acuity 0.07-0.1. The two families presented different fundus appearances, MERGs and implicit times on 30 Hz flicker white light full-field ERGs. Genetic analysis revealed one unique sequence variation in exon 19 of the ABCA4 gene, in one allele from the patients of one of the families. This point mutation causes the amino acid substitution T972N in the ABCR protein. CONCLUSION Two pairs of siblings with STGD1 presented two different expressions of the disease regarding the distribution of the retinal dysfunction. One possible molecular explanation to the different clinical expressions may be the T972N substitution present in the ABCR protein in one of the STGD1 families investigated.
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Affiliation(s)
- L Eksandh
- Department of Ophthalmology, University Hospital of Lund, Sweden.
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Li J, Tso MO, Lam TT. Reduced amplitude and delayed latency in foveal response of multifocal electroretinogram in early age related macular degeneration. Br J Ophthalmol 2001; 85:287-90. [PMID: 11222332 PMCID: PMC1723891 DOI: 10.1136/bjo.85.3.287] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM To explore the use of multifocal electroretinograms (MERG) in detecting early changes in age related macular degeneration (AMD). METHOD 15 pre-AMD or early AMD eyes showing retinal drusen or irregular fundus pigmentation with window defects by fluorescein angiography (FA) and mildly decreased visual acuity were examined and compared with their asymptomatic fellow eyes. 20 age matched normal eyes were included as controls. MERG was recorded by a Veris system (version 3.0) using a 103 hexagon stimulus and 218 second total recording time per eye. The first order kernel was used to calculate amplitudes and latencies in three configurations: the nasal and the temporal areas, the superior and the inferior areas, and six concentric rings centred on the fovea. RESULTS There were no significant differences in the amplitudes and the latencies between the different regions (nasal versus temporal and superior versus inferior) of the retina as well as between the different groups of eyes (normal, pre-AMD or early AMD, and the asymptomatic fellow eyes) in each region. Using the concentric configuration, the foveal amplitude of pre-AMD or early AMD eyes was significantly suppressed when compared with the age matched control group and their average latency was longer in the fovea than in outer rings and significantly prolonged when compared with the normal control group. Similar changes in amplitude and latency were also observed in the asymptomatic fellow eyes. CONCLUSION Significant abnormality in the foveal amplitude and the foveal latency of MERG could be detected in pre-AMD or early AMD eyes as well as their asymptomatic contralateral eyes, suggesting MERG as a sensitive tool in detecting early foveal abnormalities in AMD.
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Affiliation(s)
- J Li
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong
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40
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Abstract
There are a wide range of variables which can influence the quality of the multifocal response. It is possible to place these variables into one of four categories. First, the method of stimulus delivery will determine the field of view, interference levels and the duration of on-state stimulation. Second, data acquisition variables such as electrode type and placement, amplifier specifications and filter bandwidth settings will have a direct impact on waveform shape and on the topographic distribution of signal amplitudes. Third, patient variables such as fixation, pupil dilation and refractive error will also contribute to the multifocal response. Fourth, there are many measurements that can be taken from multifocal recordings. In addition to standard amplitude and implicit time measures (the implicit time measure in the multifocal response is becoming increasingly important particularly in early stages of disease processes), the scalar product measure provides information on waveform shape. The conventional impulse and higher order responses will be different for different modes of stimulation such as Cathode Ray Tube (CRT) and Liquid Crystal Display (LCD) systems and latency shifts will be introduced if not corrected in software. Procedures which could lead to misleading interpretation include artefact rejection, averaging with neighbours and summing of responses. These procedures should be handled with caution.
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Affiliation(s)
- D Keating
- ElectroDiagnostic Imaging Unit, Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, Scotland, UK
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41
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Abstract
The multifocal ERG using the m-sequence stimulation technique allows the derivation of 61 - 241 local ERG signals in a central visual field of about 60 degree diameter in a short time between 4 and 16 min. A recording in a light adapted state offers local information comparable to cone responses in the full-field ERG. Retinal functional losses due to regional disorders in outer retinal layers can be described in detail with this technique. In maculopathies decreased or absent central ERGs are found surrounded by normal ERG. The extent of the central lesion can be estimated. In diseases of the outer retina the pattern of distribution of multifocal ERG activity is similar to the the pattern of the visual field defect. In addition to decreased ERG amplitudes a delay of implicit time may be an important sign of pathology, i.e. the pronounced delay of implicit times in the periphery in retinitis pigmentosa and the implicit time delays in regions associated with retinal edema like CRVO and cystoid macula edema in intermediate uveitis. No simple correlation of the first order kernel multifocal ERG and field defects could be found in disorders of the ganglion cell layer. The multifocal ERG is therefore useful in the differential diagnosis of retinal and optic nerve diseases.
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Affiliation(s)
- U Kretschmann
- University Eye Hospital, Dept. of Pathophysiology of Vision and Neuro-Ophthalmology, Tübingen, Germany
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42
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Abstract
There is evidence that recording the photopic ON- and OFF-responses with long-duration stimuli is useful for determining the contribution of the cone ON- and OFF-pathways to the primate photopic electroretinogram (ERG). In this study, the optimal conditions for recording multifocal ON-OFF responses are described, and the technique is applied to normal subjects and two patients with unusual retinal diseases. The results from the normal subjects demonstrated that there were topographical variations of the photopic ERG waveform: when responses were normalized to the ON-response (b-wave) amplitude, the OFF-response (d-wave) amplitude increased with increasing eccentricity. The changes in the waveform in two patients suggested relatively greater defects of the hyperpolarizing or depolarizing bipolar cells. We conclude that the multifocal ERG technique with long-duration stimuli can be a useful tool to assess the function of local cone ON- and OFF-pathways in normal and diseased retinas.
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Affiliation(s)
- M Kondo
- The Department of Ophthalmology, Nagoya University School of Medicine, Japan.
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43
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Abstract
Static visual perimetry and the multifocal technique both measure the local effects of diseases of the retina and optic tract. The purpose here is to relate the measures obtained from each technique and to describe this relationship in some diseases. It is important to measure both the implicit time and amplitude of the multifocal ERG (mERG) or multifocal VEP (mVEP) responses. Some diseases affect one measure of the responses but not the other. The comparison of either measure to local sensitivity changes measured with static perimetry (e.g. the Humphrey 24-2 and 30-2) presents a problem. Different stimulus displays are employed. Further, the multifocal responses are displayed with arbitrary spacing between the responses. One approach is to measure the amplitude and implicit time of the multifocal responses and display these values on the same coordinates as in the visual field plots. This allows a qualitative comparison of fields and multifocal responses on the same scale. A second approach involves modifying the Humphrey perimeter software so that the test spots are placed in the centers of the multifocal stimuli (e.g. the center of each hexagon of the mERG display). A third approach involves estimating the thresholds for the regions of the multifocal display by interpolating from values at the standard Humphrey locations. The second and third approaches produce a one-to-one mapping of the multifocal and field measures and allow a quantitative comparison between the two. The relationship between visual fields and multifocal responses, determined through one or more of these approaches, is different depending upon whether the disease primarily affects the outer retina (retinitis pigmentosa), ganglion cell (glaucoma), or optic nerve (ischemic optic neuropathy and optic neuritis).
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Affiliation(s)
- D C Hood
- Department of Psychology, Columbia University, New York, NY 10027-7004, USA.
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44
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Abstract
To measure and compare the multifocal electroretinogram in control group and patients with age-related maculopathies, 17 eyes of control subjects, 9 eyes of wet-form ARMD, 8 eyes of dry-form ARMD and 14 eyes of idiopathic macular hole were tested with VERIS Sciences 4.0. The latencies and average response densities of 6 ring retinal regions in control eyes were compared with those in ARMD and macular hole. The amplitude depression and latency prolongation were found in age-related maculopathies. The changes of multifocal ERG were dramatic in wet-form ARMD and moderate in dry-form ARMD and IMH, which were correspondent with the pathological changes of the diseases. Our results suggest that the multifocal electroretinogram can be used to quantity the visual function in age-related maculopathies.
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Affiliation(s)
- S Huang
- Zhongshan Ophthalmic Center Sun Yat-sen University of Medical Sciences, Guangzhou, China.
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45
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Abstract
With the multifocal technique, as developed by Erich Sutter and colleagues, scores of focal electroretinogram (ERG) responses can be obtained in a matter of minutes. Although this technique is relatively new, it has already provided insights into the mechanisms of retinal disease. However, because it is new, there also remain questions about how it works and what it measures. This chapter considers some of these insights and some of these questions. The first part (Section 2) describes how the multifocal ERG (mERG) is recorded and considers its relationship to the full-field ERG. The mERG responses are shown to be from relatively local regions of the retina and are comprised of the same components as the full-field ERG. The diagnostic advantage of the mERG as compared to the full-field ERG is also illustrated. In Section 3, the effects of damage to different cell layers of the retina are shown to affect the mERG differently, and these changes are summarized within a conceptual framework. It is argued, for example, that when diseases of the receptor outer segment, like retinitis pigmentosa, result in small, depressed mERG responses, then the damage is, as expected, at the outer segment. However, when these diseases result in mERG responses that are reasonably large but very delayed, then the damage is beyond the outer segment, probably in the outer plexiform layer. The implicit time of the mERG, not amplitude, is the more sensitive measure of damage in degenerative diseases of the receptors. On the other hand, diseases, like glaucoma, which act on the ganglion axon, do not result in easily identified changes to the mERG unless inner retinal damage is involved as well. Inner retinal damage changes the waveform of the mERG and decreases the naso-temporal variation normally observed. Finally, diseases, like diabetes, that act on more than one layer of the retina can have a range of effects. In Section 4, recent work with the monkey mERG is reviewed, with emphasis on the relevance to human diseases. For example, blocking the sodium-based action potentials produced by ganglion and amacrine cells eliminates the naso-temporal variation in the monkey mERG and these altered mERG responses resemble those from some patients with diabetes or glaucoma. Finally, in Section 5 the second-order kernel is described. The presence of a second-order kernel has important implications for understanding the shape of the mERG response (first-order kernel). Full-field simulations of the mERG paradigm illustrate that the first-order kernel is comprised of responses with different waveforms. Further, it is argued that the nonlinear, adaptive mechanisms that produce the second-order kernel are involved in shaping the time course of the response. Patients with large, but abnormally delayed mERG responses (first-order kernel), do not have a detectable second-order kernel. It is speculated that a markedly diminished second-order kernel is diagnostic of outer plexiform layer damage, not inner plexiform layer damage as is commonly assumed.
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Affiliation(s)
- D C Hood
- Department of Psychology, Columbia University, 116th and Broadway, NY 10027-7004, New York, USA.
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46
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Abstract
The First Order Kernel responses (FOK) from a group of 15 normal subjects aged 21-36 yrs were recorded under clinical conditions with the multifocal ERG (MERG) systems VERIS and RETIscan using system-specific software and hardware under various parameter settings. First, the multifocal ERG's of normal subjects were recorded with the standard-parameters of VERIS and RETIscan. Thereafter the VERIS system parameters were set as close as possible to the RETIscan-setup, and the recordings were repeated. The VERIS parameters changed were the luminance- and contrast-settings of the stimulus-monitor and m-sequence-timing. In addition, the effects of different sampling rates were also examined. The consequences of the parameter changes were analyzed by displaying the peak times of the First-Order-Kernel (P1). The parameter-combinations used for recording lead to system-specific results. By varying the luminance/contrast settings and/or the m-sequence-timing the results can be changed. The amplitude of the recorded results can be influenced by the luminance-settings of the stimulus-monitor, and the topography of the P1 peak times is affected by the m-/f-frame-combination of the recording stimulus. With their standard parameters, the two systems give different measures of the P1 peak times. By adjusting the recording parameters, these differences can be reduced significantly. The main parameter here is the m-sequence-timing, although the sampling rate must also be taken into account with regard to the accuracy of the recording results.
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Affiliation(s)
- M Bock
- Department of Pediatric Ophthalmology, Strabismology and Ophthalmogenetics, University of Regensburg, Germany.
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Falsini B, Iarossi G, Fadda A, Porrello G, Valentini P, Piccardi M, Scullica L. The fundamental and second harmonic of the photopic flicker electroretinogram: temporal frequency-dependent abnormalities in retinitis pigmentosa. Clin Neurophysiol 1999; 110:1554-62. [PMID: 10479022 DOI: 10.1016/s1388-2457(99)00106-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The flicker electroretinogram (FERG) consists mainly of a linear (fundamental, 1F) and a non linear (second harmonic, 2F) component. Previous results indicate that 2F originates more proximally in the retina than 1F, and that retinitis pigmentosa (RP) may affect 2F to a greater extent than 1F. The aim of this study was to evaluate FERG 1F and 2F abnormalities in RP as a function of the stimulus temporal frequency (TF). METHODS Twelve patients with typical RP and 10 age-matched controls were examined. FERGs were recorded in response to uniform fields (18 degrees) presented in the macula on a light-adapting background. Stimuli were flickered sinusoidally at different, closely spaced TFs between 3.7 and 52 Hz. Amplitudes and phases of the Fourier analysed 1F and 2F components were measured. Components' apparent latencies were estimated from the rate at which phase lagged with TF. RESULTS When compared to controls, mean 1F amplitudes of patients were reduced at both low (3.7-12.6 Hz) and high (14-52 Hz) TFs, with greatest losses (0.5 log units) around the peaks (3.7 and 41 Hz) of the normal TF function. Mean 2F amplitudes were reduced mainly at low TFs, with greatest losses (0.5 log units) at 5-8 Hz. On average, the shape of the 2F, but not 1F amplitude versus TF function, differed between patients and controls, showing a selective attenuation at low TFs. Mean 1F apparent latencies were delayed at both low and high TFs, with greater delays at low (85 ms) than at high (33 ms) TFs. Mean 2F apparent latencies were delayed only at low TFs (58 ms). CONCLUSIONS In RP, 1F and 2F phase delays as well as 2F amplitude losses are dependent on TF, suggesting that FERG generators' subpopulations in both distal and proximal retina are differentially affected. Analysis of the FERG TF response is potentially useful to characterize cone system dysfunction in different genetic subtypes of RP.
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Affiliation(s)
- B Falsini
- Department of Ophthalmology, Catholic University, Rome, Italy.
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48
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Abstract
In this article, the methodologies and clinical applications of two electrophysiological tests, the focal electroretinogram (FERG) and the visual evoked potentials (VEPs) after photostress, are described. These techniques provide somewhat complementary results about macular function because they tap the activity of different neural substrates along the pathway of the cone system and allow evaluation of the macular function under steady-state (ie, the FERG) or dynamic (ie, the VEPs after photostress) conditions. The results obtained in patients with different macular pathologies indicate that while the FERG provides direct information about the extent and sites of macular dysfunction, the VEPs after photostress represent an objective, although not specific, index of the dynamic properties of macular performance after exposure to intense light stimulation. The combined use of both techniques appears to be promising for gaining further insights into the diagnosis and pathophysiology of macular diseases.
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Affiliation(s)
- V Parisi
- Cattedra di Clinica Oculistica, Università di Roma Tor Vergata, Roma, Italy
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