The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

Binns, Alison; Mortlock, Katharine Eirlys; North, R. V.

doi:10.1007/s10633-010-9257-7

Cited by 19 publications

(22 citation statements)

References 44 publications

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“…The PhNR stimulusresponse relations, up to saturation, illustrated in Figure 3 were fit with the generalized Naka-Rushton function. 30,31 Inspection of parameters of the fits in Table 3, show that saturated amplitude (V max ) differed among groups, consistent with the statistical analysis reported above. However, the other parameters were relatively stable across groups.…”

Section: Correlation Between Phnr Amplitude and Visual Sensitivity Mesupporting

confidence: 82%

“…The exponent, n, was fairly close to 1 in all cases, indicating a roughly linear rise of the response amplitude with increasing flash strength before the response saturated as previously reported for the PhNR. 31 A measure of sensitivity, I 0 , (stimulus strength necessary for a response of one-half V max ), was also similar across groups, and was not significantly correlated with either decibels or sensitivity (1/L) in any of the MS patient groups.…”

Section: Correlation Between Phnr Amplitude and Visual Sensitivity Mementioning

confidence: 83%

“…The PhNR stimulus-response relation from the smallest response to saturation was fit with the generalized Naka-Rushton function 30,31 :…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

Wang

Cheng

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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Section: Correlation Between Phnr Amplitude and Visual Sensitivity Mesupporting

confidence: 82%

Section: Correlation Between Phnr Amplitude and Visual Sensitivity Mementioning

confidence: 83%

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The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

Wang

Cheng

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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“…For the PhNR, n was fixed at 1.2 (consistent with our pilot data, and similar to others). 44,45 Further, the PhNR Vmax was analyzed as a ratio to the b-wave Vmax (Vmax ratio) to account for any changes to the b-wave between sessions.…”

Section: Discussionmentioning

confidence: 99%

Improvement in Inner Retinal Function in Glaucoma with Nicotinamide (Vitamin B₃) Supplementation: A Crossover Randomised Clinical Trial

Hui

Tang

Williams

et al. 2020

Preprint

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Importance: Retinal ganglion cells endure significant metabolic stress with ageing and glaucoma-related stressors. Injured cells require increased energy for repair but maintain capacity to recover function despite periods of functional loss. Nicotinamide, a precursor of redox co-factor and metabolite, NAD+, is low in serum of patients with primary open-angle glaucoma and its supplementation provides robust protection of retinal ganglion cells by targeting mitochondrial health in glaucoma models. However, the potential of nicotinamide to improve retinal ganglion cell function in humans with glaucoma is yet unknown. Objective: To determine whether nicotinamide supplementation taken in conjunction with conventional IOP-lowering therapy leads to early improvement in retinal ganglion cell function in people with glaucoma. Design: Crossover, double-masked, randomized clinical trial conducted between October 2017 to January 2019. Setting: Study participants recruited from two tertiary care centers in Melbourne, Australia. Participants: Adults diagnosed and treated for primary glaucoma. Ninety-four participants assessed for study eligibility. Intervention: Participants randomized to first receive oral placebo or nicotinamide and reviewed six-weekly. Accelerated dosing method utilized; participants commenced 6-week course of 1.5 grams/day followed by 6 weeks of 3.0 grams/day. After 12 weeks, participants crossed over to other intervention for 12 weeks without washout. At each visit, visual function measured using full-field flash electroretinography and white-on-white perimetry. Main outcome measures: Primary endpoint was change in inner retinal function determined a-priori as change in photopic negative response (PhNR) parameters: saturated PhNR amplitude (Vmax), ratio of PhNR/b-wave amplitude (Vmax ratio). Results: Fifty-seven participants (65.5±10.0 years, 39% female) enrolled. PhNR Vmax improved beyond 95% coefficient of repeatability (COR) in 23% of participants following 12 weeks of nicotinamide versus 9% on placebo. Conversely, PhNR Vmax deteriorated in 9% on placebo and 7% on nicotinamide. Overall, Vmax improved by 14.8% [95% CI: 2.8%, 26.9%], (p=0.02) on nicotinamide and 5.2% [-4.2%, 14.6%], (p=0.27) on placebo. Vmax ratio improved on average by 12.6% [5.0%, 20.2%], (p=0.002) following nicotinamide and 3.6% [-3.4%, 10.5%], (p=0.30) on placebo. A concomitant trend for improved visual field mean deviation was observed with 27% improving ≥1dB on nicotinamide and fewer deteriorating ≥1dB (4%) compared to placebo (p=0.02). Moderate correlation was observed between PhNR and visual field change with treatment. Participants demonstrated excellent treatment adherence rates (>94%) and nicotinamide was well tolerated with minimal side effects. Conclusions and Relevance: Nicotinamide supplementation can improve inner retinal function in patients receiving concurrent IOP-lowering glaucoma therapy. Further studies are underway to elucidate the effects of long-term nicotinamide supplementation on glaucoma progression.

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“…This negatively impacts on the accurate estimation of the PhNR, especially when measured with respect to the baseline. 12 – 14 …”

Section: Introductionmentioning

confidence: 99%

Baseline Detrending for the Photopic Negative Response

Tang

Hui

Coote

et al. 2018

Trans. Vis. Sci. Tech.

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PurposeThe photopic negative response (PhNR) of the light-adapted electroretinogram (ERG) holds promise as an objective marker of retinal ganglion cell function. We compared baseline detrending methods to improve PhNR repeatability without compromising its diagnostic ability in glaucoma.MethodsPhotopic ERGs were recorded in 20 glaucoma and 18 age-matched control participants. A total of 50 brief, red-flashes (1.6 cd.s/m2) on a blue background (10 photopic cd/m2) were delivered using the RETeval device. Detrending methods compared were: (1) increasing the high-pass filter from 1 to 10 Hz and (2) estimating and removing the trend with an increasing polynomial (order from 1–10) applied to the prestimulus interval, prestimulus and postsignal interval, or the whole ERG signal. Coefficient of repeatability (COR%), unpaired Student's t-test, and area under the receiver operating characteristic curve (AUC) were used to compare the detrending methods.ResultsMost detrending methods improved PhNR test–retest repeatability compared to the International Society for Clinical Electrophysiology of Vision (ISCEV) recommended 0.3 to 300 Hz band-pass filter (COR% ± 200%). In particular, detrending with a polynomial (order 3) applied to the whole signal performed the best (COR% ± 44%) while achieving similar diagnostic ability as ISCEV band-pass (AUC 0.74 vs. 0.75, respectively). However, over-correcting with higher orders of processing can cause waveform distortion and reduce diagnostic ability.ConclusionsBaseline detrending can improve the PhNR repeatability without compromising its clinical use in glaucoma. Further studies exploring more complex processing methods are encouraged.Translational RelevanceBaseline detrending can significantly improve the quality of the PhNR.

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The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

Cited by 19 publications

References 44 publications

The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

Improvement in Inner Retinal Function in Glaucoma with Nicotinamide (Vitamin B₃) Supplementation: A Crossover Randomised Clinical Trial

Baseline Detrending for the Photopic Negative Response

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The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

Cited by 19 publications

References 44 publications

The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

The Photopic Negative Response of the Flash Electroretinogram in Multiple Sclerosis

Improvement in Inner Retinal Function in Glaucoma with Nicotinamide (Vitamin B3) Supplementation: A Crossover Randomised Clinical Trial

Baseline Detrending for the Photopic Negative Response

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Product

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Improvement in Inner Retinal Function in Glaucoma with Nicotinamide (Vitamin B₃) Supplementation: A Crossover Randomised Clinical Trial