In vivo electroretinographic differentiation of rod, short-wavelength and long/medium-wavelength cone responses in dogs using silent substitution stimuli

Mowat, Freya M.; Wise, E N; Oh, Annie; Foster, Melanie L.; Kremers, Jan

doi:10.1016/j.exer.2019.05.013

Cited by 6 publications

(10 citation statements)

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“…Animals were not euthanized for the purpose of the study. Three normal adult purpose‐bred beagles (1 male aged 31.3 months, and 2 females aged 29.6 months and 37.3 months) were studied: a subset of animals previously published using the more extensive ERG protocol performed under general anesthesia (propofol induction, isoflurane maintenance) 4 . Animals were dark‐adapted for 1 hour.…”

Section: Methodsmentioning

confidence: 99%

“…Topical mydriatics (0.5% tropicamide and 2.5% phenylephrine; Akorn Pharmaceuticals) were applied prior to systemic drug administration. Anesthesia protocols have previously been published in detail 4 . Anesthesia protocols were performed prior to sedated protocols with a minimum washout period of 3 days between protocols.…”

Section: Methodsmentioning

confidence: 99%

“…Topical analgesia was applied (0.5% proparacaine; Akorn Pharmaceuticals). Protocols and analysis of silent substitution ERG were as previously published using color LED light stimuli administered in a Ganzfeld dome (Q450SC; Roland Consult) 4 with the following exceptions: Stay sutures were not used to maintain primary gaze; the rod protocol was performed at 3.25 cd/m 2 and 4‐20 Hz, the L/M‐cone protocol at 32.5 cd/m 2 luminance and 24‐50 Hz, and the S‐cone protocol at 130 cd/m 2 and 4‐20 Hz (performed in that order). These adjustments were made based on the findings from the published study, 4 reflecting the optimal isolation conditions for each photoreceptor class.…”

Section: Methodsmentioning

confidence: 99%

“…(Figure 1A) 2,3 Traditional electroretinography (ERG) uses white light of different intensities and with dark‐ or light‐adaptation states to differentiate rod photoreceptors (sensitive to low luminance, maximal responses in the dark‐adapted state, minimized or ablated responses in the light‐adapted state) from cone photoreceptors (sensitive to higher luminance, isolated responses in the light‐adapted state). However, separation of L/M‐ and S‐cone subclass function using ERG in dogs has only recently been proven 4 …”

Section: Introductionmentioning

confidence: 99%

“…Although silent substitution photoreceptor subclass isolation using ERG has been proven in dogs, the method published was lengthy and performed under general anesthesia, limiting its potential applicability in clinical patients with retinal disorders 4 . This is an important limitation, considering the wealth of inherited retinal disorders described in dogs, 6,7 a number of which have cone‐ or rod‐specific abnormalities.…”

Section: Introductionmentioning

confidence: 99%

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A modified silent substitution electroretinography protocol to separate photoreceptor subclass function in lightly sedated dogs

Wise

Foster

Kremers

et al. 2020

Veterinary Ophthalmology

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Objective A previously published study successfully isolated photoreceptor responses from canine rods, long/medium‐wavelength (L/M) cones, and short‐wavelength (S) cones using silent substitution electroretinography (ERG) performed under general anesthesia. We hypothesized that responses would be similar in dogs under sedation and that a curtailed protocol suitable for use in clinical patients could effectively isolate responses from all three photoreceptor subtypes. Animals studied Three normal adult purpose‐bred beagles (2 females and 1 male). Methods Dogs were dark‐adapted for 1 hour. Sine wave color stimuli were delivered using LEDs in a Ganzfeld dome. The ERG protocol under anesthesia was performed as previously published; sedated ERG protocols were performed after a 3‐day washout period. Intravenous sedation (dexmedetomidine 1.25 mcg/kg, butorphanol 0.1 mg/kg) was administered for sedation. Statistical analysis was performed using two‐way repeated‐measures ANOVA and linear regression. Results In both anesthetized and sedated animals, rod‐derived responses peaked at low frequency (4‐12 Hz), L/M‐cone responses peaked at high frequency (32‐38 Hz), and S‐cone responses peaked at low frequency (4‐12 Hz). The frequencies eliciting maximal responses were similar in sedated and anesthetized protocols, although rod amplitudes were significantly higher in the sedated protocols compared with anesthetized (P < .001). Conclusion We present a clinically applicable method to consistently isolate rod and cone subclass function in sedated dogs. This may allow detailed evaluation of photoreceptor function in clinical patients with rod or cone subclass deficits without the need for general anesthesia or protracted adaptation times.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%