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Park S, Raghunathan VK, Ramarapu R, Moshiri A, Yiu G, Casanova MI, Cosert K, McCorkell M, Leonard BC, Thomasy SM. Biomechanic, proteomic and miRNA transcriptional changes in the trabecular meshwork of primates injected with intravitreal triamcinolone. Vision Res 2024; 222:108456. [PMID: 38991466 DOI: 10.1016/j.visres.2024.108456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/13/2024]
Abstract
Although biomechanical changes of the trabecular meshwork (TM) are important to the pathogenesis of glucocorticoids-induced ocular hypertension (GC-OHT), there is a knowledge gap in the underlying molecular mechanisms of the development of it. In this study, we performed intravitreal triamcinolone injection (IVTA) in one eye of 3 rhesus macaques. Following IVTA, we assessed TM stiffness using atomic force microscopy and investigated changes in proteomic and miRNA expression profiles. One of 3 macaques developed GC-OHT with a difference in intraocular pressure of 4.2 mmHg and a stiffer TM with a mean increase in elastic moduli of 0.60 kPa versus the non-injected control eye. In the IVTA-treated eyes, proteins associated with extracellular matrix remodeling, cytoskeletal rearrangement, and mitochondrial oxidoreductation were significantly upregulated. The significantly upregulated miR-29b and downregulated miR-335-5p post-IVTA supported the role of oxidative stress and mitophagy in the GC-mediated biomechanical changes in TM, respectively. The significant upregulation of miR-15/16 cluster post-IVTA may indicate a resultant TM cell apoptosis contributing to the increase in outflow resistance. Despite the small sample size, these results expand our knowledge of GC-mediated responses in the TM and furthermore, may help explain steroid responsiveness in clinical settings.
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Affiliation(s)
- Sangwan Park
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | | | - Raneesh Ramarapu
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Ala Moshiri
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, 95817, USA
| | - Glenn Yiu
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, 95817, USA
| | - M Isabel Casanova
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Krista Cosert
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Michelle McCorkell
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, 95817, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, 95817, USA; California National Primate Research Center, University of California-Davis, Davis, CA, 95616, USA.
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Hidaka T, Chuman H, Ikeda Y. Evaluation of inner retinal function at different stages of primary open angle glaucoma using the photopic negative response (PhNR) measured by RETeval electroretinography. Graefes Arch Clin Exp Ophthalmol 2024; 262:161-169. [PMID: 37535182 DOI: 10.1007/s00417-023-06193-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/28/2023] [Accepted: 07/23/2023] [Indexed: 08/04/2023] Open
Abstract
PURPOSE To investigate the objective function of the inner retinal layer in each stage of primary open angle glaucoma (POAG) using the photopic negative response (PhNR) measured by RETeval full-field electroretinography (ERG), and to identify which PhNR parameter is the most useful. METHODS Ninety eyes of 90 patients with POAG (30 with mild POAG (mean deviation (MD) ≥ -6 dB) and 60 with moderate-to-advanced POAG (MD < -6 dB)) and 76 eyes of 76 control cases were examined. We investigated six PhNR parameters and their relationships with the results of the Humphrey 30-2 visual field test and the thickness of the circumpapillary retinal nerve fiber layer (cpRNFL) obtained from optical coherence tomography. The following PhNR parameters were assessed: base-to-trough (BT), peak-to-trough (PT), 72msPhNR, the W-ratio, P-ratio, implicit time (IT), and a-wave and b-wave amplitudes on ERG. RESULTS All PhNR parameters other than IT significantly differed between the all POAG (all stages) and control groups and between the moderate-to-advanced POAG and control groups. BT and 72msPhNR in the mild POAG group, significantly differed from those in the control group. Regarding the relationships between PhNR parameters and the visual field and between these parameters and cpRNFL thickness, correlations were observed between all PhNR parameters, except PT and IT, and both the visual field and cpRNFL thickness in the all and moderate-to-advanced POAG groups. 72msPhNR correlated with cpRNFL thickness in the mild POAG group. The area under the receiver operating characteristic curve was greater for BT than for the other PhNR parameters in both the mild and moderate-to-advanced POAG groups. The discriminant linear function for examining the presence or absence of POAG and the threshold for diagnosis were quantitatively obtained as follows. Regarding BT: discriminant = 0.505 × BT + 2.017; threshold = positive for POAG, negative for no POAG; correct answer rate = 80.7%. Concerning 72msPhNR: discriminant = 0.533 × 72msPhNR + 1.553; threshold = positive for POAG and negative for no POAG; correct answer rate = 77.1%. CONCLUSION RETeval-measured PhNR parameters were useful for an objective evaluation of visual function in moderate-to-advanced POAG. BT appeared to be the most diagnostically useful parameter.
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Affiliation(s)
- Takako Hidaka
- Department of Ophthalmology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki Prefecture, 889-1692, Japan.
| | - Hideki Chuman
- Department of Ophthalmology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki Prefecture, 889-1692, Japan
| | - Yasuhiro Ikeda
- Department of Ophthalmology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki Prefecture, 889-1692, Japan
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Cvenkel B, Sustar M, Perovšek D. Monitoring for glaucoma progression with SAP, electroretinography (PERG and PhNR) and OCT. Doc Ophthalmol 2021; 144:17-30. [PMID: 34652598 PMCID: PMC8882567 DOI: 10.1007/s10633-021-09854-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 09/14/2021] [Indexed: 11/30/2022]
Abstract
Purpose To investigate the value of pattern electroretinography (PERG) and photopic negative response (PhNR) in monitoring glaucoma compared to standard clinical tests (standard automated perimetry (SAP) and clinical optic disc assessment) and structural measurements using spectral-domain OCT. Methods A prospective study included 32 subjects (32 eyes) with ocular hypertension, suspect or early glaucoma monitored for progression with clinical examination, SAP, PERG, PhNR and OCT for at least 4 years. Progression was defined clinically by the documented change of the optic disc and/or significant visual field progression (EyeSuite™ trend analysis). One eye per patient was included in the analysis. Results During the follow-up, 13 eyes (40.6%) showed progression, whereas 19 remained stable. In the progressing group, all parameters showed significant worsening over time, except for the PhNR, whereas in the stable group only the OCT parameters showed a significant decrease at the last visit. The trend of change over time using linear regression was steepest for the OCT parameters. At baseline, only the ganglion cell complex (GCC) and peripapillary retinal nerve fibre (pRNFL) thicknesses significantly discriminated between the stable and progressing eyes with the area under the ROC curve of 0.72 and 0.71, respectively. The inter-session variability for the first two visits in the stable group was lower for OCT (% limits of agreement within ± 17.4% of the mean for pRNFL and ± 3.6% for the GCC thicknesses) than for ERG measures (within ± 35.9% of the mean for PERG N95 and ± 59.9% for PhNR). The coefficient of variation for repeated measurements in the stable group was 11.9% for PERG N95 and 23.6% for the PhNR, while it was considerably lower for all OCT measures (5.6% for pRNFL and 1.7% for GCC thicknesses). Conclusions Although PERG and PhNR are sensitive for early detection of glaucomatous damage, they have limited usefulness in monitoring glaucoma progression in clinical practice, mainly due to high inter-session variability. On the contrary, OCT measures show low inter-session variability and might have a predicting value for early discrimination of progressing cases. Supplementary Information The online version contains supplementary material available at 10.1007/s10633-021-09854-8.
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Affiliation(s)
- Barbara Cvenkel
- Department of Ophthalmology, University Medical Centre Ljubljana, Grabloviceva 46, 1000, Ljubljana, Slovenia. .,Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.
| | - Maja Sustar
- Department of Ophthalmology, University Medical Centre Ljubljana, Grabloviceva 46, 1000, Ljubljana, Slovenia
| | - Darko Perovšek
- Department of Ophthalmology, University Medical Centre Ljubljana, Grabloviceva 46, 1000, Ljubljana, Slovenia
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Prencipe M, Perossini T, Brancoli G, Perossini M. The photopic negative response (PhNR): measurement approaches and utility in glaucoma. Int Ophthalmol 2020; 40:3565-3576. [PMID: 32737731 PMCID: PMC7669808 DOI: 10.1007/s10792-020-01515-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/17/2020] [Indexed: 11/22/2022]
Abstract
Purpose Visual electrophysiological testing continues to generate interest among glaucoma experts because of its potential help in clarifying disease pathophysiology and promoting early detection of glaucomatous damage. The photopic negative response (PhNR) is a slow negative component of the full-field electroretinogram that has been shown to provide specific information about retinal ganglion cells (RGCs) activity. The purpose of this article is to review the literature to explore the currently available measurement methods and the utility of PhNR in glaucoma diagnostic process. Methods We gathered publications related to the origins, types of stimuli used, measurements methods and applications of the PhNR of ERG in animal models and humans through a search of the literature cited in PubMed. Search terms were: “PhNR”, “photopic negative response”, “glaucoma”, “glaucomatous optic neuropathy”, “ERG”, “electroretinogram”. Results The most reliable PhNR measurements are obtained using a red stimulus on a blue background, without requiring refractive correction, fixation monitoring, or ocular media transparency. Given its direct correlation with RGCs response, the PhNR measured as baseline-to-trough (BT) represents the most reliable parameter of evaluation. Glaucoma patients with evident perimetric defects show pathologic PhNR values. Even though the PhNR is promising in detecting early RGCs impairment, distinguishing between healthy subjects and suspect patients at risk of developing glaucomatous damage still remains challenging. Conclusion The PhNR is a useful additional tool to explore disorders that affect the innermost retina, including glaucoma and other forms of optic neuropathy. In particular, comparing reports of the standard examinations (optic disc assessment, OCT RNFL measurement, standard automated perimetry) with the results of electrophysiological tests may be helpful in solving clinical diagnostic and management dilemmas. On the one hand, the PhNR of the ERG can examine the parvocellular pathways; on the other hand, the steady-state pattern ERG optimized for glaucoma screening (PERGLA) can explore the magnocellular pathways. This could give ophthalmologists a useful feedback to identify early RGCs alterations suggestive of glaucoma, stratify the risk and potentially monitor disease progression.
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Affiliation(s)
- Matteo Prencipe
- Department of Surgical, Medical, Molecular Pathology and of Critical Area, University of Pisa, Pisa, Italy.
| | - Tommaso Perossini
- Studio Oculistico Associato Mario and Tommaso Perossini, Livorno, Italy
| | | | - Mario Perossini
- Studio Oculistico Associato Mario and Tommaso Perossini, Livorno, Italy
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Berezovsky A, Karanjia R, Fernandes AG, Botelho GIS, Bueno TLN, Ferraz NN, Sacai PY, Coupland SG, Sadun AA, Salomão SR. Photopic negative response using a handheld mini-ganzfeld stimulator in healthy adults: normative values, intra- and inter-session variability. Doc Ophthalmol 2020; 142:153-163. [PMID: 32681419 DOI: 10.1007/s10633-020-09784-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/08/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine normative values, intra- and inter-session variability for a range of parameters derived from the photopic negative response (PhNR) using a handheld mini-Ganzfeld stimulator in healthy normal adults. METHODS Light-adapted flash full-field electroretinograms (ERGs) were recorded from healthy individuals with no visual complaints, visual acuity equal to or better than 0.0 logMAR (20/20 Snellen), and negative family history for visual diseases. ERGs were recorded from both eyes using a DTL® type fiber electrode after dilation of the pupils with instillation of 1 drop of tropicamide eye drops (1%). The full-field PhNR stimulus conditions were produced by a LED-based ColorBurst™ (Diagnosys LLC, Lowell, MA, USA) handheld stimulator. Red flashes of 1, 5 and 7 cd.s/m2 on a blue background of 10 cd/m2 were presented. A-wave, b-wave and PhNR amplitude (determined by both baseline to trough-BT and peak to trough-PT) and peak times were analyzed. Normal limits were determined as 5% percentile for amplitudes and 95% percentile for latencies. Intra- and inter-session variability were assessed with Wilcoxon signed-rank test, intraclass correlation coefficient (ICC) and the coefficient of variability (COV). RESULTS Normative limits for PhNR amplitude (µV) using 1, 5 and 7 cd.s./m2 stimuli were, respectively: 20.81; 18.06 and 19.60 for BT and 69.11; 77.98; 76.51 for PT. Peak times (ms) normative limits for 1, 5 and 7 cd.s/m2 intensities were, respectively, 65.98; 78.20 and 77.96. Overall, intra-session variability assessed by coefficients of variation ranged from 1.35 to 10.28%. Inter-session variability disclosed significant intraclass correlation values for all PhNR parameters only for 1 cd.s/m2 stimuli. CONCLUSIONS The normative values provided by this study are clinically helpful in the diagnosis of inner retinal disorders, especially those affecting retinal ganglion cells such as glaucoma and other optic neuropathies. Further studies, including a larger sample with variable age range would extend the validity of the current results.
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Affiliation(s)
- Adriana Berezovsky
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
| | - Rustum Karanjia
- Doheny Eye Institute, Los Angeles, California, USA.,Department of Ophthalmology, David Geffen School of Medicine at UCLA, Doheny Eye Center, Los Angeles, California, USA.,Ottawa Eye Institute, University of Ottawa, Ottawa, ON, Canada.,Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Arthur Gustavo Fernandes
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Gabriel Izan Santos Botelho
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Tatiane Luana Novele Bueno
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Nívea Nunes Ferraz
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Paula Yuri Sacai
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Stuart Glenn Coupland
- Ottawa Eye Institute, University of Ottawa, Ottawa, ON, Canada.,Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Alfredo Arrigo Sadun
- Doheny Eye Institute, Los Angeles, California, USA.,Department of Ophthalmology, David Geffen School of Medicine at UCLA, Doheny Eye Center, Los Angeles, California, USA
| | - Solange Rios Salomão
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
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Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study. Ophthalmology 2017; 124:1175-1185. [PMID: 28434717 PMCID: PMC5540060 DOI: 10.1016/j.ophtha.2017.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 11/23/2022] Open
Abstract
Purpose To estimate heritability of parameters of human retinal electrophysiology and to explore which parameters change with age. Design Prospective, classic twin study. Participants Adult monozygotic and dizygotic twin pairs recruited from the TwinsUK cohort. Methods Electroretinogram responses were recorded using conductive fiber electrodes in response to stimuli incorporating standards set by the International Society for the Clinical Electrophysiology of Vision. These parameters were extracted; in addition, photopic negative-response (PhNR; originating from retinal ganglion cells) and i-wave components were extracted from responses to the photopic single flash. Parameter values were averaged from both eyes. Main Outcome Measures Mean values were calculated for the cohort. Correlation coefficients with age were calculated (averaging parameters from both twins from each pair). Coefficients of intrapair correlation were calculated for monozygotic and dizygotic twins. Age-adjusted heritability estimates were derived using standard maximum likelihood structural equation twin modeling. Results Responses were recorded from 210 participants in total (59 monozygotic and 46 dizygotic twin pairs). Ninety-three percent were women. Mean age for the cohort was 62.4 years (standard deviation, 11.4 years). In general, response amplitudes correlated negatively, and implicit times positively, with age. Correlations were statistically significant (P < 0.05) and moderate or strong (coefficient, >0.35) for the following parameters: scotopic standard and bright-flash a-wave implicit times, photopic 30-Hz flicker and single-flash b-wave implicit times, and PhNR and i-wave implicit times. Intrapair correlations were higher for monozygotic than dizygotic twins, suggesting important genetic influences. Age-adjusted estimates of heritability were significant for all parameters (except scotopic dim-flash b-wave implicit time), ranging from 0.34 to 0.85. Highest estimates were for photopic single-flash a-wave and b-wave amplitudes (0.84 and 0.85, respectively). Conclusions This study explored heritability of retinal electrophysiologic parameters and included measurements reflecting ganglion cell function. Most parameters showed significant heritability, indicating that genetic factors are important, determining up to 85% of the variance in some cone system response parameters. Scotopic responses tended to show lower heritability (possibly relating to greater rod system susceptibility to environmental factors). Future studies can explore the identity of these genetic factors, improving our understanding of how they shape retinal function.
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Comparing three different modes of electroretinography in experimental glaucoma: diagnostic performance and correlation to structure. Doc Ophthalmol 2017; 134:111-128. [PMID: 28243926 DOI: 10.1007/s10633-017-9578-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 02/13/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To compare diagnostic performance and structure-function correlations of multifocal electroretinogram (mfERG), full-field flash ERG (ff-ERG) photopic negative response (PhNR) and transient pattern-reversal ERG (PERG) in a non-human primate (NHP) model of experimental glaucoma (EG). METHODS At baseline and after induction of chronic unilateral IOP elevation, 43 NHP had alternating weekly recordings of retinal nerve fiber layer thickness (RNFLT) by spectral domain OCT (Spectralis) and retinal function by mfERG (7F slow-sequence stimulus, VERIS), ff-ERG (red 0.42 log cd-s/m2 flashes on blue 30 scotopic cd/m2 background, LKC UTAS-E3000), and PERG (0.8° checks, 99% contrast, 100 cd/m2 mean, 5 reversals/s, VERIS). All NHP were followed at least until HRT-confirmed optic nerve head posterior deformation, most to later stages. mfERG responses were filtered into low- and high-frequency components (LFC, HFC, >75 Hz). Peak-to-trough amplitudes of LFC features (N1, P1, N2) and HFC RMS amplitudes were measured and ratios calculated for HFC:P1 and N2:P1. ff-ERG parameters included A-wave (at 10 ms), B-wave (trough-to-peak) and PhNR (baseline-to-trough) amplitudes as well as PhNR:B-wave ratio. PERG parameters included P50 and N95 amplitudes as well as N95:P50 ratio and N95 slope. Diagnostic performance of retinal function parameters was compared using the area under the receiver operating characteristic curve (A-ROC) to discriminate between EG and control eyes. Correlations to RNFLT were compared using Steiger's test. RESULTS Study duration was 15 ± 8 months. At final follow-up, structural damage in EG eyes measured by RNFLT ranged from 9% above baseline (BL) to 58% below BL; 29/43 EG eyes (67%) and 0/43 of the fellow control eyes exhibited significant (>7%) loss of RNFLT from BL. Using raw parameter values, the largest A-ROC findings for mfERG were: HFC (0.82) and HFC:P1 (0.90); for ff-ERG: PhNR (0.90) and PhNR:B-wave (0.88) and for PERG: P50 (0.64) and N95 (0.61). A-ROC increased when data were expressed as % change from BL, but the pattern of results persisted. At 95% specificity, the diagnostic sensitivity of mfERG HFC:P1 ratio was best, followed by PhNR and PERG. The correlation to RNFLT was stronger for mfERG HFC (R = 0.65) than for PhNR (R = 0.59) or PERG N95 (R = 0.36), (p = 0.20, p = 0.0006, respectively). The PhNR flagged a few EG eyes at the final time point that had not been flagged by mfERG HFC or PERG. CONCLUSIONS Diagnostic performance and structure-function correlation were strongest for mfERG HFC as compared with ff-ERG PhNR or PERG in NHP EG.
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Van Alstine AW, Viswanathan S. Test-retest reliability of the multifocal photopic negative response. Doc Ophthalmol 2016; 134:25-36. [PMID: 28035520 DOI: 10.1007/s10633-016-9569-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/20/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE To assess the test-retest reliability of the multifocal photopic negative response (mfPhNR) of normal human subjects. METHODS Multifocal electroretinograms were recorded from one eye of 61 healthy adult subjects on two separate days using a Visual Evoked Response Imaging System software version 4.3 (EDI, San Mateo, California). The visual stimulus delivered on a 75-Hz monitor consisted of seven equal-sized hexagons each subtending 12° of visual angle. The m-step exponent was 9, and the m-sequence was slowed to include at least 30 blank frames after each flash. Only the first slice of the first-order kernel was analyzed. The mfPhNR amplitude was measured at a fixed time in the trough from baseline (BT) as well as at the same fixed time in the trough from the preceding b-wave peak (PT). Additionally, we also analyzed BT normalized either to PT (BT/PT) or to the b-wave amplitude (BT/b-wave). The relative reliability of test-retest differences for each test location was estimated by the Wilcoxon matched-pair signed-rank test and intraclass correlation coefficients (ICC). Absolute test-retest reliability was estimated by Bland-Altman analysis. RESULTS The test-retest amplitude differences for neither of the two measurement techniques were statistically significant as determined by Wilcoxon matched-pair signed-rank test. PT measurements showed greater ICC values than BT amplitude measurements for all test locations. For each measurement technique, the ICC value of the macular response was greater than that of the surrounding locations. The mean test-retest difference was close to zero for both techniques at each of the test locations, and while the coefficient of reliability (COR-1.96 times the standard deviation of the test-retest difference) was comparable for the two techniques at each test location when expressed in nanovolts, the %COR (COR normalized to the mean test and retest amplitudes) was superior for PT than BT measurements. The ICC and COR were comparable for the BT/PT and BT/b-wave ratios and were better than the ICC and COR for BT but worse than PT. CONCLUSION mfPhNR amplitude measured at a fixed time in the trough from the preceding b-wave peak (PT) shows greater test-retest reliability when compared to amplitude measurement from baseline (BT) or BT amplitude normalized to either the PT or b-wave amplitudes.
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Affiliation(s)
| | - Suresh Viswanathan
- College of Optometry, State University of New York, 33 West 42nd Street, New York, NY, 10036, USA.
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Assessing the Contribution of the Oscillatory Potentials to the Genesis of the Photopic ERG with the Discrete Wavelet Transform. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2790194. [PMID: 28101507 PMCID: PMC5217158 DOI: 10.1155/2016/2790194] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/24/2016] [Accepted: 11/02/2016] [Indexed: 11/17/2022]
Abstract
The electroretinogram (ERG) is composed of slow (i.e., a-, b-waves) and fast (i.e., oscillatory potentials: OPs) components. OPs have been shown to be preferably affected in some diseases (such as diabetic retinopathy), while the a- and b-waves remain relatively intact. The purpose of this study was to determine the contribution of OPs to the building of the ERG and to examine whether a signal mostly composed of OPs could also exist. DWT analyses were performed on photopic ERGs (flash intensities: −2.23 to 2.64 log cd·s·m−2 in 21 steps) obtained from normal subjects (n = 40) and patients (n = 21) affected with a retinopathy. In controls, the %OP value (i.e., OPs energy/ERG energy) is stimulus- and amplitude-independent (range: 56.6–61.6%; CV = 6.3%). In contrast, the %OPs measured from the ERGs of our patients varied significantly more (range: 35.4%–89.2%; p < 0.05) depending on the pathology, some presenting with ERGs that are almost solely composed of OPs. In conclusion, patients may present with a wide range of %OP values. Findings herein also support the hypothesis that, in certain conditions, the photopic ERG can be mostly composed of high-frequency components.
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Kundra H, Park JC, McAnany JJ. Comparison of photopic negative response measurements in the time and time-frequency domains. Doc Ophthalmol 2016; 133:91-98. [PMID: 27562839 DOI: 10.1007/s10633-016-9558-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/15/2016] [Indexed: 11/30/2022]
Abstract
PURPOSE To compare measurements of the full-field photopic negative response (PhNR), as well as intra-subject variation in the PhNR, using time and time-frequency domain analyses. METHODS Full-field ERGs were recorded from 20 normally sighted subjects (aged 24-65 years) elicited by a long-wavelength pulse (3 cd s m-2) presented against a short-wavelength adapting field (12.5 cd m-2). Three to 10 waveforms were obtained from each subject, and each waveform was analyzed using standard time domain analyses of the PhNR, as well as a discrete wavelet transform (DWT) to extract time-frequency components that correspond to the PhNR. Three different measures of the PhNR were derived and compared: (1) amplitude at the PhNR trough; (2) amplitude at 72 ms following stimulus onset; (3) energy in the 11 Hz, 60-120 ms DWT frequency bin that corresponds to the PhNR. In addition, the effect of normalizing the PhNR by the b-wave was evaluated for each of the measures. Coefficients of variation (CVs) were computed for each definition to evaluate intra-subject variation. RESULTS PhNR amplitudes measured at the trough and at 72 ms were significantly correlated (r = 0.88, p < 0.001). Additionally, PhNR energy derived by DWT was significantly correlated with the amplitude measured at the trough (r = 0.64, p = 0.002) and at 72 ms (r = 0.60, p = 0.005). Mean (±SD) intra-subject CVs were 26 % (15 %), 49 % (26 %), and 30 % (15 %), for measures at the trough, 72 ms, and DWT, respectively. Normalization by the b-wave amplitude (i.e., PhNR/b) had minimal effect on the intra-subject CVs, whereas normalization by the sum of the b-wave and PhNR amplitudes (i.e., PhNR/[b + PhNR]) substantially reduced the CVs for all three measures (mean CVs were less than 17 % for all conditions). CONCLUSIONS Although each PhNR definition has advantages and disadvantages, all three metrics provide similar estimates of the PhNR. Intra-subject CVs, however, were relatively high for measurements made at 72 ms, indicating that definitions based on a fixed time point may introduce variability. The substantial decrease in intra-subject variation after normalization by the sum of the PhNR and b-wave amplitudes may be advantageous under some conditions.
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Affiliation(s)
- Hansa Kundra
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St., Chicago, IL, 60612, USA.,Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan St., Chicago, IL, 60607, USA
| | - Jason C Park
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St., Chicago, IL, 60612, USA
| | - J Jason McAnany
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St., Chicago, IL, 60612, USA. .,Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan St., Chicago, IL, 60607, USA. .,Department of Psychology, University of Illinois at Chicago, 1007 W. Harrison St., Chicago, IL, 60612, USA.
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Wu Z, Hadoux X, Hui F, Sarossy MG, Crowston JG. Photopic Negative Response Obtained Using a Handheld Electroretinogram Device: Determining the Optimal Measure and Repeatability. Transl Vis Sci Technol 2016; 5:8. [PMID: 27540494 PMCID: PMC4981488 DOI: 10.1167/tvst.5.4.8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/24/2016] [Indexed: 12/01/2022] Open
Abstract
Purpose To determine the measure of the photopic negative response (PhNR) of the full-field electroretinogram (ERG) that exhibits the optimal level of test-retest repeatability, and examine its repeatability under different conditions using a handheld, nonmydriatic ERG system and self-adhering skin electrodes. Methods Multiple ERG recordings (using 200 sweeps each) were performed in both eyes of 20 normal participants at two different sessions to compare its coefficient of repeatability (CoR; where 95% of the test-retest difference is expected to lie) between different PhNR measures and under different testing conditions (within and between examiners, and between sessions). Results The ratio between the PhNR trough to b-wave peak and b-wave peak to a-wave trough amplitude (PhNR/B ratio) exhibited the lowest CoR relative to its effective dynamic range (30 ± 4%) when including three recordings. There were no significant changes in the PhNR/B ratio over seven measurements (4 right and 3 left eyes) at either session (P ≥ 0.100), or significant difference in its CoR between different testing conditions (P = 0.314). Conclusion The PhNR/B ratio was the measure that minimized variability, and its measurements using a novel handheld ERG system with self-adhering skin electrodes and the protocols described in this study were comparable under different testing conditions and over multiple recordings. Translational Relevance The PhNR can be measured for clinical and research purposes using a simple-to-implement technique that is consistent within and between visits, and also between examiners.
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Affiliation(s)
- Zhichao Wu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Xavier Hadoux
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Flora Hui
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Marc G Sarossy
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Jonathan G Crowston
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
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Abstract
PURPOSE OF REVIEW Electrophysiological measures of vision function have for decades generated interest among glaucoma researchers and clinicians alike because of their potential to help elucidate pathophysiological processes and sequence of glaucomatous damage, as well as to offer a potential complementary metric of function that might be more sensitive than standard automated perimetry. The purpose of this article is to review the recent literature to provide an update on the role of the electroretinogram (ERG) in glaucoma diagnosis. RECENT FINDINGS The pattern reversal ERG (PERG) and the photopic negative response (PhNR) of the cone-driven full-field, focal or multifocal ERG provide objective measures of retinal ganglion cell function and are all sensitive to glaucomatous damage. Recent studies demonstrate that a reduced PERG amplitude is predictive of subsequent visual field conversion (from normal to glaucomatous) and an increased rate of progressive retinal nerve fiber layer thinning in suspect eyes, indicating a potential role for PERG in risk stratification. Converging evidence indicates that some portion of PERG and PhNR abnormality represents a reversible aspect of dysfunction in glaucoma. SUMMARY PERG and PhNR responses obtained from the central macula are capable of detecting early-stage, reversible glaucomatous dysfunction.
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Kinoshita J, Takada S, Iwata N, Tani Y. Comparison of photopic negative response (PhNR) between focal macular and full-field electroretinograms in monkeys. Doc Ophthalmol 2016; 132:177-87. [PMID: 27071393 DOI: 10.1007/s10633-016-9538-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 04/06/2016] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare the characteristics of the photopic negative response (PhNR) between the focal macular and full-field electroretinograms (ERGs) in monkeys. METHODS Both focal macular and full-field photopic ERGs were recorded in four cynomolgus monkeys under identical stimulus and recording conditions except for which area of the retina was illuminated. The luminance and duration of red flash stimuli were varied in the presence of steady blue background illumination. These ERGs were recorded before and after intravitreal injection of tetrodotoxin (TTX). RESULTS Several differences were identified between the focal macular and full-field ERGs, including: (1) The PhNR/b-wave amplitude ratio was higher in the focal macular than in the full-field ERGs, and (2) the stimulus threshold of the focal macular PhNR was lower than that of the full-field PhNR. For both macular and full-field stimulation conditions, (1) PhNR amplitude generally increased with increasing stimulus luminance; (2) PhNR implicit time was independent of the stimulus luminance; (3) PhNR amplitude and implicit time increased with increasing stimulus duration up to 50 ms, while a further increase in stimulus duration produced no change in amplitude or implicit time; and (4) PhNR amplitude was selectively attenuated by TTX. CONCLUSIONS Both the focal macular and full-field PhNRs reflect the functional properties of the inner retina including the retinal ganglion cells (RGCs). Relative to the b-wave, the contribution is weighted more heavily in the focal macular than in the full-field PhNR. Furthermore, these results support the idea that the focal macular PhNR can be an indicator of the function of the macular RGCs.
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Affiliation(s)
- Junzo Kinoshita
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo, 134-8630, Japan.
| | - Shunsuke Takada
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo, 134-8630, Japan
| | - Noriaki Iwata
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo, 134-8630, Japan
| | - Yoshiro Tani
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo, 134-8630, Japan
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Wu Z, Hadoux X, Fan Gaskin JC, Sarossy MG, Crowston JG. Measuring the Photopic Negative Response: Viability of Skin Electrodes and Variability Across Disease Severities in Glaucoma. Transl Vis Sci Technol 2016; 5:13. [PMID: 26998406 PMCID: PMC4795588 DOI: 10.1167/tvst.5.2.13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/12/2016] [Indexed: 12/05/2022] Open
Abstract
PURPOSE The purpose of this study was to determine the feasibility of measuring the photopic negative response (PhNR) of the full-field electroretinogram (ERG) using skin electrodes compared to conjunctival electrodes and its test-retest variability over a range of disease severities in open-angle glaucoma. METHODS Recordings were performed twice (100 sweeps each) within the same session in 43 eyes of 23 participants with glaucoma to determine its intrinsic variability. The ratio between the PhNR and B-wave amplitude (PhNR/B ratio) was determined for each trace and computed across 5 to 100 sweeps of each recording. Spectral-domain optical coherence tomography was used to measure the average peripapillary retinal nerve fiber layer (RNFL) thickness. RESULTS The PhNR/B ratio and its magnitude of variability were not significantly different between skin and conjunctival electrodes (P ≤ 0.197), and the degree of variability decreased substantially with increasing number of sweeps. For skin electrodes, the intraclass correlation coefficient was 0.89 and 0.91 for right and left eyes, respectively. The variability of the PhNR/B ratio decreased with lower RNFL thickness values and larger B-wave amplitudes (P ≤ 0.002). CONCLUSIONS Skin electrodes are a viable alternative to conjunctival electrodes when measuring the PhNR in open angle glaucoma, and increasing the number of sweeps substantially reduced its intrinsic variability; the extent of variability was also lower with worsening disease severity. TRANSLATIONAL RELEVANCE The feasibility of performing ERG recordings widely across a range of disease severities in glaucoma can be achieved through using skin electrodes and increasing the number of sweeps performed to improve measurement repeatability.
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Affiliation(s)
- Zhichao Wu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Xavier Hadoux
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Jennifer C. Fan Gaskin
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Marc G. Sarossy
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Jonathan G. Crowston
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
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15
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The non-human primate experimental glaucoma model. Exp Eye Res 2015; 141:57-73. [PMID: 26070984 DOI: 10.1016/j.exer.2015.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/03/2015] [Accepted: 06/06/2015] [Indexed: 01/05/2023]
Abstract
The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.
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Tang J, Edwards T, Crowston JG, Sarossy M. The Test-Retest Reliability of the Photopic Negative Response (PhNR). Transl Vis Sci Technol 2014; 3:1. [PMID: 25374770 DOI: 10.1167/tvst.3.6.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/24/2014] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The photopic negative response (PhNR) may be useful as a tool to monitor longitudinal change in retinal ganglion cell (RGC) function. The goal was to assess PhNR test-retest reliability, and to estimate the amount of change between tests that is likely to be statistically significant for an individual test subject. METHODS Photopic electroretinograms (ERGs) were recorded from 49 visually normal subjects (mean age, 38.9 years; range, 21-72 years). Signals were acquired using Dawson-Trick-Litzkow (DTL) electrodes in response to red stimulus at four flash energies (0.5, 1, 2.25, 3 cd·s/m2) on a blue background (10 cd/m2). The PhNR amplitude was recorded from prestimulus baseline to trough (BT), prestimulus baseline to fixed time point (BF), and b-wave peak to trough (PT). The ratio of baseline PhNR to b-wave amplitude (BT/b-wave) was calculated. Reliability was assessed using the intraclass correlation coefficient (ICC2,1) and coefficient of repeatability (CoR). RESULTS Flash energy of 1.00 cd·s/m2 produced reliable, well-defined traces. At this stimulus, the a- and b-wave amplitudes were reproduced with moderate reliability (ICC, 0.62; CoR%, 90.0%; and ICC, 0.74; CoR%, 54.3%; respectively). For PhNR, the order from most to least reliable measurement was: PT (ICC, 0.64; CoR%, 59.1%), BT (ICC, 0.40; CoR%, 148.3%), and BF (ICC, 0.22; CoR%, 166.1%). The BT/b-wave did not improve reliability (ICC, 0.37; CoR%, 181.5). CONCLUSION The b-wave peak-to-PhNR trough amplitude produced the most reliable measurement. TRANSLATIONAL RELEVANCE A relatively large magnitude of change in PhNR amplitude is required to make clinical inferences about changes in RGC function. Refinement to the technique of acquisition and/or processing of the PhNR is recommended to improve reliability.
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Affiliation(s)
- Jessica Tang
- Centre for Eye Research Australia, Melbourne, Australia
| | - Thomas Edwards
- The Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Jonathan G Crowston
- Centre for Eye Research Australia, Melbourne, Australia ; The Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Marc Sarossy
- Centre for Eye Research Australia, Melbourne, Australia ; RMIT University, Melbourne, Australia
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Bui BV, He Z, Vingrys AJ, Nguyen CTO, Wong VHY, Fortune B. Using the electroretinogram to understand how intraocular pressure elevation affects the rat retina. J Ophthalmol 2013; 2013:262467. [PMID: 23431417 PMCID: PMC3570935 DOI: 10.1155/2013/262467] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 10/24/2012] [Indexed: 11/17/2022] Open
Abstract
Intraocular pressure (IOP) elevation is a key risk factor for glaucoma. Our understanding of the effect that IOP elevation has on the eye has been greatly enhanced by the application of the electroretinogram (ERG). In this paper, we describe how the ERG in the rodent eye is affected by changes in IOP magnitude, duration, and number of spikes. We consider how the variables of blood pressure and age can modify the effect of IOP elevation on the ERG. Finally, we contrast the effects that acute and chronic IOP elevation can have on the rodent ERG.
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Affiliation(s)
- Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Algis J. Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Christine T. O. Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Vickie H. Y. Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Brad Fortune
- Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, OR 97232, USA
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Beddaoui M, Coupland SG, Tsilfidis C. Recovery of function following regeneration of the damaged retina in the adult newt, Notophthalmus viridescens. Doc Ophthalmol 2012; 125:91-100. [DOI: 10.1007/s10633-012-9338-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 06/01/2012] [Indexed: 11/30/2022]
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The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram. Doc Ophthalmol 2011; 122:39-52. [DOI: 10.1007/s10633-010-9257-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
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Mortlock KE, Binns AM, Aldebasi YH, North RV. Inter-subject, inter-ocular and inter-session repeatability of the photopic negative response of the electroretinogram recorded using DTL and skin electrodes. Doc Ophthalmol 2010; 121:123-34. [PMID: 20607349 DOI: 10.1007/s10633-010-9239-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 06/21/2010] [Indexed: 10/19/2022]
Abstract
The photopic negative response (PhNR) has attracted interest as a flash ERG component reflecting inner retinal activity, with investigators adopting various approaches to analysing the response. This study has two principal aims: first to determine the most reliable technique for assessing the PhNR amplitude; secondly to compare the repeatability characteristics of the PhNR recorded using DTL and skin active electrodes. Electroretinograms were recorded in 31 subjects, using both electrode types, in response to a Ganzfeld red stimulus (Lee filter "bright red"; 1.76 log phot td.s; 4 Hz) presented over a steady blue background (Schott glass filter BG28; 3.9 log scot td). Sixteen subjects returned to assess repeatability. PhNR amplitude was measured from b-wave peak-to-PhNR trough, pre-stimulus baseline to trough, and from peak and baseline to a fixed time-point; a ratio of b-wave/PhNR amplitude was also calculated. Coefficients of variation (CoV), and inter-ocular and inter-session limits of agreement (LoA) were calculated for all measures. The ratio of b-wave/PhNR amplitude showed the lowest CoV (14.3% DTL; 23.2% skin), inter-ocular LoA (22.2% DTL; 25.0% skin), and inter-session LoA (22.8% DTL; 20.3% skin). The peak-to-trough and peak-to-fixed-time measurements were also consistently reliable. Least reliable measures were those measured from baseline. While skin electrode responses were significantly smaller than DTL responses (P < 0.0001), the variability was only slightly increased. This study suggests that peak-to-trough measurements are the most reliable means of measuring the PhNR and ratio calculation further improves repeatability. Skin electrodes provided a viable alternative to DTL electrodes for recording the PhNR.
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Affiliation(s)
- Katharine E Mortlock
- School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4LU, UK
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Kremers J, Doelemeyer A, Polska EA, Moret F, Lambert C, Lambrou GN. Multifocal electroretinographical changes in monkeys with experimental ocular hypertension: a longitudinal study. Doc Ophthalmol 2008; 117:47-63. [PMID: 18167014 DOI: 10.1007/s10633-007-9102-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 11/21/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE To study the time course of changes in the multifocal electroretinograms (mfERG) in monkeys with experimental ocular hypertension (OHT). METHODS The mfERGs were recorded in 12 eyes out of 6 monkeys. Two baseline measurements were used to quantify the reproducibility, the inter-ocular and the inter-individual variability of the ERG signals. Thereafter, the trabeculum of one eye of each animal was laser-coagulated in one to three sessions to induce OHT. ERG measurements were repeated regularly in a period of 18 months and the changes in ERG waveforms were quantified. RESULTS All animals displayed OHT (between 20 and 50 mmHg) in the laser-coagulated eyes. An ERG change was defined as the sum of differences during the first 90 ms between the laser-coagulated eye and the same eye before laser coagulation and between the laser-coagulated eye and the non-treated fellow eye. Three animals displayed significant changes for nearly all retinal areas and all stimulus conditions. The three remaining animals displayed significant changes only in one comparison, indicating very mild changes. The data indicate that a high stimulus contrast is more sensitive to detect changes, probably because of a better signal-to-noise ratio. Moreover, the comparisons with the fellow eye are more sensitive to detect changes than comparisons with the measurements before laser-coagulation. CONCLUSIONS OHT does not always lead to ERG changes. Comparisons with fellow eyes using high contrast stimuli are more sensitive to detect changes related to OHT.
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Affiliation(s)
- Jan Kremers
- Novartis Institutes for Biomedical Research, 4002 Basel, Switzerland.
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Yamada K, Matsumoto CS, Nakatsuka K. Effect of spatial frequency of stimulus on focal macular ERGs in monkeys : fmacERG dependence on the spatial-frequency. Doc Ophthalmol 2006; 113:83-91. [PMID: 17028912 DOI: 10.1007/s10633-006-9017-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 07/26/2006] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine the effect of the spatial frequency of a small grating stimulus centered on the macula on the focal macular ERGs (fmacERGs) of monkeys. METHODS fmacERGs were recorded from eight eyes of four adult monkeys (Macaca fuscata). The spatial frequency of the stimulus was changed from 0.25 to 8 cycles/degree. The luminance of the light bars was 10 cd/m(2), and the contrast was 95%. The stimulus was flashed on and off with an on duration of 100 ms and an off duration of 150 ms (4 Hz). The stimulus was centered on the fovea and subtended 12.7 degrees at the cornea. The luminance of the steady light-adapting background was 3.5 cd/m(2). The location of the stimulus on the retina was monitored throughout the recordings. The effects of the spatial frequency of the stimulus on the amplitudes and implicit times of the a-waves, b-waves, and oscillatory potentials (OPs) were determined. fmacERGs were also recorded following intravitreal tetrodotoxin (TTX). RESULTS The amplitudes of the a- and b-waves did not change with changes in the spatial frequency of the stimulus. The OPs, on the other hand, responded best to the lowest spatial frequency, and the OPs after the first two were attenuated at intermediate and higher frequencies (Wilcoxon signed-rank test: P < 0.05). TTX reduced all OP wavelets in monkeys. CONCLUSIONS The OPs of the photopic macular ERGs are affected by the spatial frequency of the stimulus and are reduced by TTX, consistent with their being generated by inner retinal neurons.
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Affiliation(s)
- Kisaburo Yamada
- Department of Brain and Nerve Science, Division of Sensory and Locomotive Sciences, Ophthalmology, Oita University Faculty of Medicine, 1-1 Hasama, Oita, 879-5593, Japan
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Harrison WW, Viswanathan S, Malinovsky VE. Multifocal pattern electroretinogram: cellular origins and clinical implications. Optom Vis Sci 2006; 83:473-85. [PMID: 16840872 DOI: 10.1097/01.opx.0000218319.61580.a5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSES The purposes of this article are to gain insight into the cellular origins of the multifocal pattern electroretinogram (mPERG) and evaluate its potential for clinical use. METHODS mPERGs were recorded from four anesthetized monkeys before and after pharmacologic blockade of light-driven activity of inner-retinal neurons and from 55 normal human subjects (19-91 years) and six patients with glaucoma (43-77 years of age). Stimuli consisted of counterphase-modulated black and white triangles organized in 61-scaled hexagons with mean luminance 100 cd/m2 and 100% contrast. The stimulus array subtended 31 degrees vertically and 37 degrees horizontally at 48 cm. The amplifier cutoff frequencies were 3 and 100 Hz. Responses were grouped as quadrants and the first slice of the second-order kernel was analyzed. RESULTS The mPERG responses of monkeys and humans were similar. In the monkey responses, there was an early positive potential (P1) around 25 ms and a later positive potential (P2) found selectively in the nasal field quadrants around 31 ms. These responses were seen around 22 and 36 ms in the human responses. After blockade of inner-retinal activity in monkeys, P1 amplitude was greatly reduced at all retinal locations and P2 was eliminated. P1 and P2 amplitudes were significantly reduced in the glaucomatous eyes relative to amplitudes of age-matched controls. Reductions in the amplitudes of P1 and P2 could easily discriminate between glaucomatous visual field quadrants with and without behavioral sensitivity losses. However, these alterations are likely to reflect diffuse losses. CONCLUSIONS mPERG responses contain prominent contributions from inner-retinal neurons that can be reduced in glaucomatous eyes. These findings raise the possibility that the mPERG could be potentially useful in the objective estimation of neural damage in glaucoma. However, further refinement of recording techniques will be required if the mPERG is to be used to detect focal damage.
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Affiliation(s)
- Wendy W Harrison
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA
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Li B, Barnes GE, Holt WF. The decline of the photopic negative response (PhNR) in the rat after optic nerve transection. Doc Ophthalmol 2006; 111:23-31. [PMID: 16502304 DOI: 10.1007/s10633-005-2629-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2005] [Indexed: 11/28/2022]
Abstract
PURPOSE To investigate the contribution to the photopic negative response (PhNR) of the electroretinogram (ERG) by retinal ganglion cells (RGCs). The PhNR was assessed longitudinally following optic nerve transection (ONTx). METHODS Photopic ERGs were recorded from each eye of an anesthetized (ketamine/xylazine, 60 mg/kg and 5 mg/kg) Brown Norway rat using custom made electrodes (PT-IR Tef., A-M System Inc). ERGs were elicited using green Ganzfeld flashes (11.38 scd/m(2), 22.76 cds/m(2)) and a rod suppressing green-background (40 cd/m(2)). PhNRs were compared before and after optic nerves were transected. Cresyl violet stained retinal flatmounts were used to estimate cell loss in the ganglion cell layer 3 and 15 weeks after optic nerve transection. The pharmacological effect of 1.3 microM intravitreal TTX on the PhNR was also evaluated. RESULTS There was a significant loss (p <0.05) in the PhNR of 20, 36, 34, 35, 48, 48 and 56% for ONTx eye versus the contralateral eye, at post ONTx times of 24 h, 1, 2, 3, 4, 8 and 15 weeks. B-wave amplitudes of ONTx eyes were not significantly different from the control eyes. In ONTx eyes, mean cell loss in the retinal ganglion cell layer was 27 and 55% at the 3 week and 15 week time periods. In the eyes with ONTx, the decline of PhNR amplitudes was correlated positively with RGC loss (r = 0.98; p < 0.01). Thirty minutes after intravitreal TTX injection, the PhNR was significantly reduced (57%, p<0.01). CONCLUSIONS There was a time-dependent decline in the PhNR after ONTx, as exemplified by a 35% reduction from 1-3 weeks, a 48% decline for 4-8 weeks and a 56% decline after 15 weeks. The correlation between the decline in the PhNR and retinal ganglion cell loss suggests that the PhNR depends on inner retina integrity and the PhNR may be important biological signal or detecting glaucomatous damage and the monitoring of RGC function changes in early glaucoma.
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Affiliation(s)
- B Li
- Alcon Research Ltd., Fort Worth, TX 76134, USA.
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