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Retinal Characterization of the Thy1-GCaMP3 Transgenic Mouse Line After Optic Nerve Transection
摘要： PURPOSE. GCaMP3 is a genetically encoded calcium indicator for monitoring intracellular calcium dynamics. We characterized the expression pattern and functional properties of GCaMP3 in the Thy1-GCaMP3 transgenic mouse retina. METHODS. To determine the specificity of GCaMP3 expression, Thy1-GCaMP3 (B6; CBA-Tg(Thy1-GCaMP3)6Gfng/J) retinas were processed for immunohistochemistry with anti-green fluorescent protein (anti-GFP, to enhance GCaMP3 fluorescence), anti-RBPMS (retinal ganglion cell [RGC]–specific marker), and antibodies against amacrine cell markers (ChAT, GABA, GAD67, syntaxin). Calcium imaging was used to characterize functional responses of GCaMP3-expressing (GCaMP+) cells by recording calcium transients evoked by superfusion of kainic acid (KA; 10, 50, or 100 μM). In a subset of animals, optic nerve transection (ONT) was performed 3, 5, or 7 days prior to calcium imaging. RESULTS. GFP immunoreactivity colocalized with RBPMS but not amacrine cell markers in both ONT and non-ONT (control) groups. Calcium transients evoked by KA were reduced after ONT (50 μM KA; ΔF/F0 [SD]; control: 1.00 [0.67], day 3: 0.50 [0.35], day 5: 0.31 [0.28], day 7: 0.35 [0.36]; P < 0.05 versus control). There was also a decrease in the number of GCaMP3+ cells after ONT (cells/mm2 [SD]; control: 2198 [453], day 3: 2224 [643], day 5: 1383 [375], day 7: 913 [178]; P < 0.05). Furthermore, the proportion of GCaMP3+ cells that responded to KA decreased after ONT (50 μM KA, 97%, 54%, 47%, and 58%; control, 3, 5, and 7 days, respectively). CONCLUSIONS. Following ONT, functional RGC responses are lost prior to the loss of RGC somata, suggesting that anatomical markers of RGCs may underestimate the extent of RGC dysfunction.
关键词： GCaMP3,retinal ganglion cells,Thy1-GCaMP3,calcium imaging,optic nerve transection
更新于2025-09-23 15:22:29
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Electrical activation of degenerated photoreceptors in blind mouse retina elicited network-mediated responses in different types of ganglion cells
摘要： Electrical (e-) stimulation is explored in schemes to rescue the vision of blind people, e.g. those affected by Retinitis Pigmentosa (RP). We e-activated subretinally the surviving degenerated photoreceptors (d-Phrs) of the rd1 mouse (RP model) and evoked visual responses in the blind retina. The e-stimulation was applied with a single platinum/iridium electrode. The d-Phrs (calcium-imaging) and ganglion cells (GC) activity (MEA-recording) were recorded in simultaneous multilayer recordings. The findings of this study confirm that the d-Phrs responded to e-stimulation and modulated the retinal network-activity. The application of blockers revealed that the synaptic interactions were dependent on voltage-gated calcium channels and mediated by the transmitters glutamate and GABA. Moreover, the gap junctions coupled networks promoted the lateral-spread of the e-evoked activity in the outer (~60 μm) and inner (~120 μm) retina. The activated GCs were identified as subtypes of the ON, OFF and ON-OFF classes. In conclusion, d-Phrs are the ideal interface partners for implants to elicit enhanced visual responses at higher temporal and spatial resolution. Furthermore, the retina’s intact circuity at the onset of complete blindness makes it a tempting target when considering the implantation of implants into young patients to provide a seamless transition from blinding to chip-aided vision.
关键词： blind retina,MEA recording,subretinal implant,gap junctions,glutamate,rd1 mouse,calcium imaging,ganglion cells,GABA,electrical stimulation,Retinitis Pigmentosa,degenerated photoreceptors
更新于2025-09-19 17:15:36
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Synaptic Specializations of Melanopsin-Retinal Ganglion Cells in Multiple Brain Regions Revealed by Genetic Label for Light and Electron Microscopy
摘要： Kim et al. express a genetically encoded electron microscopy (EM) tag in mRGCs of the mouse retina and use serial block-face electron microscopy to analyze the optic nerve and synaptic neuropil in five different brain regions. They find that mRGC synaptic terminals show target-specific specializations corresponding to differences in responses to light.
关键词： melanopsin,brain regions,synaptic specializations,electron microscopy,retinal ganglion cells
更新于2025-09-19 17:13:59
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Inner Retinal Changes in Primary Open-Angle Glaucoma Revealed Through Adaptive Optics-Optical Coherence Tomography
摘要： To examine the microstructural changes in the inner nuclear layer (INL) and ganglion cell layer (GCL) in a primary open-angle glaucoma (POAG) subject at 2 timepoints, 4 months apart. This case-control study (1 POAG subject and 1 normal control) used the single cell, 3-dimensional volumetric imaging capability of an adaptive optics-optical coherence tomography-scanning laser ophthalmoscopy system to examine the inner retina. At the area of greatest glaucomatous change in the POAG subject [3-degrees temporal (T), 3-degrees inferior (I), right eye], the GCL was greatly thinned at both timepoints, yet retinal ganglion cell soma remained visible amid a meshwork of capillaries. Microcystic lesions in the INL were visible at both timepoints, ranging in diameter from 8 to 43 μm on day 1 to 11 to 64 μm at 4 months, with an average diameter increase of ～124%. Small hyperre?ective features (not seen in the contralateral eye or control subject) at a depth midway through the INL seemed correlated to the development of microcysts. We demonstrate the ability to image microcystic lesions early in their development and have quanti?ed longitudinal changes. The presence of small hyperre?ective structures at a layer midway through the INL seems to be a precursor to their formation and is a potential biomarker for assessing POAG severity and progression. The adaptive optics imaging system is also able to visualize retinal ganglion cells in this subject, despite severe thinning of the GCL.
关键词： optical coherence tomography,adaptive optics,retinal ganglion cells,microcysts,primary open-angle glaucoma
更新于2025-09-16 10:30:52
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Assessment of macular ganglion cell complex using optical coherence tomography: Impact of a paediatric reference database in clinical practice
摘要： Importance: Optical coherence tomography software classifies abnormality of macular ganglion cell-inner plexiform layer thickness and macular retinal nerve fibre layer thickness based on adult series. Background: We assessed the impact of using paediatric reference macular ganglion cell complex values instead of adult reference values. Design: Cross-sectional study. Primary and tertiary health-care setting. Participants: Out of 140 healthy participants aged 5 to 18 years, 90% were eligible. Methods: Following a dilated eye examination and cycloplegic refraction, participants underwent optical coherence tomography ganglion cell scans (Topcon 3D OCT-2000; Topcon Corporation, Tokyo, Japan). Right eye measurements for superior, inferior, and total layer thickness and spherical equivalent were reported, together with age, sex and origin. Main Outcome Measures: Paediatric reference values by age and spherical equivalent were produced, and the specific agreement between paediatric and adult to percentile 5 was ganglion cell complex reference values below or equal estimated. Results: The multivariate analysis confirmed a positive association between spherical equivalent and macular ganglion cell-inner plexiform layer thickness, and between age and macular retinal nerve fibre layer (five out of six regression coefficients P values were (cid:1) 0.03). Specific agreement was 25% for ganglion cell-inner plexiform layer thickness and > 80% for macular retinal nerve fibre layer. Adult-based software identified low ganglion cell values in one in seven children compared to paediatric reference values (0.8% vs 5.5%, P = 0.031). Conclusions and Relevance: The availability of optical coherence tomography ganglion cell complex reference values for paediatric age and spherical equivalent groups can be used to improve detection of children with low cell layer thickness.
关键词： macular ganglion cell-inner plexiform layer,childhood,optical coherence tomography,children reference database,retinal ganglion cells,macular retinal nerve fibre layer,ganglion cell complex
更新于2025-09-10 09:29:36
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Functional Loss of the Inner Retina in Childhood Optic Gliomas Detected by Photopic Negative Response
摘要： To determine whether the Ganzfeld ERG photopic negative response (PhNR), an assay of inner retinal activity, is altered in childhood optic glioma (OPG). Seventeen pediatric patients with a diagnosis of OPG, established on neuro-ophthalmologic and brain/orbit magnetic resonance imaging (MRI) criteria, were enrolled. The examination protocol included determination of visual acuity (VA), fundus examination, retinal nerve fiber layer (RNFL) measurement with spectral-domain optical coherence tomography (SD-OCT) and photopic ERG. Fifteen normal children served as control group. Ten of the 17 OPG patients were retested 1 to 3 months after the first examination. Photopic ERGs were recorded after 10 minutes of light adaptation in response to a Ganzfeld flash presented on a steady light–adapting background. Amplitude and peak-time of b-wave and PhNR were measured. Compared with normal values, PhNR amplitude was significantly reduced (P < 0.0001) in the OPG group. Peak-time of PhNR as well as b-wave amplitude and peak-time were similar in both patients and controls. Losses of PhNR were found in patients with involvement of either anterior or retro-chiasmatic optic pathways. Linear regression analysis showed significant positive correlation between RNFL thickness and PhNR amplitude (r2 ? 0.34, P ? 0.008). Mean percentage test–retest difference for PhNR amplitude and peak-time was 12% and 6%, respectively. These findings indicate that flash ERG PhNR can detect a loss of inner retinal function in childhood OPGs supporting the use of this technique, as an adjunct to standard psychophysical and electrophysiological tests, to monitor visual function in OPG.
关键词： photopic negative response,optical coherence tomography,ganglion cells,optic pathways glioma,neurofibromatosis
更新于2025-09-10 09:29:36
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Parameters of ocular fundus on spectral-domain optical coherence tomography for glaucoma diagnosis
摘要： In this review, we summarize the progression of several parameters assessed by spectral-domain optical coherence tomography (SD-OCT) in recent years for the detection of glaucoma. Monitoring the progression of defects in the retinal nerve fiber layer (RNFL) thickness is essential. Imaging and analysis of retinal ganglion cells (RGCs) and inner plexiform layer (IPL), respectively, have been of great importance. Optic nerve head (ONH) topography obtained from 3D SD-OCT images is another crucial step. Other important assessments involve locating the Bruch’s membrane opening (BMO), estimating the optic disc size and rim area, and measuring the lamina cribrosa displacement. Still other parameters found in the past three years for glaucoma diagnosis comprise central retinal artery resistive index, optic disc perfusion in optical coherence tomography angiography (OCTA) study, peripapillary choroidal thickness, and choroidal area in SD-OCT. Recently, several more ocular fundus parameters have been found, and compared with the earlier parameters to judge the accuracy of diagnosis. While a few of these parameters have been widely used in clinical practice, a fair number are still in the experimental stage.
关键词： optic nerve head,retinal nerve fiber layer,lamina cribrosa,optical coherence tomography,macular thickness,ganglion cells,glaucoma progression
更新于2025-09-09 09:28:46
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The Post-Illumination Pupil Response (PIPR)
摘要： The post-illumination pupil response (PIPR) has been quantified using four metrics, but the spectral sensitivity of only one is known; here we determine the other three. To optimize the human PIPR measurement, we determine the protocol producing the largest PIPR, the duration of the PIPR, and the metric(s) with the lowest coefficient of variation. METHODS. The consensual pupil light reflex (PLR) was measured with a Maxwellian view pupillometer. Experiment 1: Spectral sensitivity of four PIPR metrics (plateau, 6 seconds, area under curve early and late recovery) was determined from a criterion PIPR to a 1-second pulse and fitted with vitamin A1 nomogram (kmax ? 482 nm). Experiment 2: The PLR was measured as a function of three stimulus durations (1 second, 10 seconds, 30 seconds), five irradiances spanning low to high melanopsin excitation levels (retinal irradiance: 9.8–14.8 log quanta.cm(cid:2)2.s(cid:2)1), and two wavelengths, one with high (465 nm) and one with low (637 nm) melanopsin excitation. Intra- and interindividual coefficients of variation (CV) were calculated. RESULTS. The melanopsin (opn4) photopigment nomogram adequately describes the spectral sensitivity of all four PIPR metrics. The PIPR amplitude was largest with 1-second short-wavelength pulses (?12.8 log quanta.cm(cid:2)2.s(cid:2)1). The plateau and 6-second PIPR showed the least intra- and interindividual CV ((cid:3)0.2). The maximum duration of the sustained PIPR was 83.0 6 48.0 seconds (mean 6 SD) for 1-second pulses and 180.1 6 106.2 seconds for 30-second pulses (465 nm; 14.8 log quanta.cm(cid:2)2.s(cid:2)1). CONCLUSIONS. All current PIPR metrics provide a direct measure of the intrinsic melanopsin photoresponse. To measure progressive changes in melanopsin function in disease, we recommend that the PIPR be measured using short-duration pulses (e.g., (cid:3)1 second) with high melanopsin excitation and analyzed with plateau and/or 6-second metrics. Our PIPR interstimulus intervals between duration data provide a baseline for the selection of consecutive pupil testing sequences.
关键词： pupil light reflex,intrinsically photosensitive retinal ganglion cells (ipRGCs),melanopsin,post-illumination pupil response
更新于2025-09-09 09:28:46
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Melanopsin-Mediated Post-Illumination Pupil Response in Early Age-Related Macular Degeneration
摘要： PURPOSE. To determine whether melanopsin-expressing intrinsically photosensitive retinal ganglion cell (ipRGC) inputs to the pupil light re?ex (PLR) are affected in early age-related macular degeneration (AMD). METHODS. The PLR was measured in 40 participants (20 early AMD and 20 age-matched controls) using a custom-built Maxwellian view pupillometer. Sinusoidal stimuli (0.5 Hz, 11.9 seconds duration, 35.68 diameter) were presented to the study eye and the consensual pupil response was measured to lights with high melanopsin excitation (464 nm [blue]) and with low melanopsin excitation (638 nm [red]) that biased activation to the outer retina. Two melanopsin PLR metrics were quanti?ed: the phase amplitude percentage (PAP) during the sinusoidal stimulus presentation and the post-illumination pupil response (PIPR). The PLR during stimulus presentation was analyzed using latency to constriction, the transient pupil response and maximum pupil constriction metrics. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curves. RESULTS. The blue PIPR was signi?cantly less sustained in the early AMD group (P < 0.001). The red PIPR was not signi?cantly different between groups (P > 0.05). The PAP and blue stimulus constriction amplitude were signi?cantly lower in the early AMD group (P < 0.05). There was no signi?cant difference between groups in the latency or transient amplitude for both stimuli (P > 0.05). ROC analysis showed excellent diagnostic accuracy for the blue PIPR metrics (area under the curve > 0.9). CONCLUSIONS. This is the initial report that the melanopsin-controlled PIPR is dysfunctional in early AMD. The noninvasive, objective measurement of the ipRGC controlled PIPR has excellent diagnostic accuracy for early AMD.
关键词： illumination pupil response,pupil light re?ex,intrinsically photosensitive retinal ganglion cells,post-illumination pupil response,ipRGCs,melanopsin
更新于2025-09-09 09:28:46
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Pattern Recognition Analysis of Age-Related Retinal Ganglion Cell Signatures in the Human Eye
摘要： PURPOSE. To characterize macular ganglion cell layer (GCL) changes with age and provide a framework to assess changes in ocular disease. This study used data clustering to analyze macular GCL patterns from optical coherence tomography (OCT) in a large cohort of subjects without ocular disease. METHODS. Single eyes of 201 patients evaluated at the Centre for Eye Health (Sydney, Australia) were retrospectively enrolled (age range, 20–85); 8 3 8 grid locations obtained from Spectralis OCT macular scans were analyzed with unsupervised classi?cation into statistically separable classes sharing common GCL thickness and change with age. The resulting classes and gridwise data were ?tted with linear and segmented linear regression curves. Additionally, normalized data were analyzed to determine regression as a percentage. Accuracy of each model was examined through comparison of predicted 50-year-old equivalent macular GCL thickness for the entire cohort to a true 50-year-old reference cohort. RESULTS. Pattern recognition clustered GCL thickness across the macula into ?ve to eight spatially concentric classes. F-test demonstrated segmented linear regression to be the most appropriate model for macular GCL change. The pattern recognition–derived and normalized model revealed less difference between the predicted macular GCL thickness and the reference cohort (average 6 SD 0.19 6 0.92 and (cid:2)0.30 6 0.61 lm) than a gridwise model (average 6 SD 0.62 6 1.43 lm). CONCLUSIONS. Pattern recognition successfully identi?ed statistically separable macular areas that undergo a segmented linear reduction with age. This regression model better predicted macular GCL thickness. The various unique spatial patterns revealed by pattern recognition combined with core GCL thickness data provide a framework to analyze GCL loss in ocular disease.
关键词： pattern recognition,aging,optical coherence tomography,ganglion cells,image analysis (clinical)
更新于2025-09-09 09:28:46