Endoplasmic Reticulum Stress Delays Choroid Development in the HCAR1 Knockout Mouse.

The subretina, composed of the choroid and the retinal pigment epithelium (RPE), plays a critical role in proper vision. In addition to phagocytosis of photoreceptor debris, the RPE shuttles oxygen and nutrients to the neuroretina. For their own energy production, RPE cells mainly rely on lactate, a major by-product of glycolysis.

Comparing the RETeval portable ERG device with more traditional tabletop ERG systems in normal subjects and selected retinopathies.

Purpose: Our study aimed to determine if ISCEV standard-like ERGs recorded with the LKC RETeval portable ERG unit compared to those obtained using the more traditional tabletop unit.

Methods: ERGs recorded from normal subjects and patients affected with retinal ON and OFF pathway anomalies were compared. Analysis included peak time and amplitude measurements as well as time-frequency domain analysis with the discrete wavelet transform of waveforms obtained with the two systems.

Resting state electroretinography: An innovative approach to intrinsic retinal function monitoring.

The electroretinogram (ERG) represents the biopotential evoked by the retina in response to a light stimulus. The flash evoked ERG (fERG) is the ERG modality most frequently used clinically to diagnose and monitor retinal disorders. We hereby present a new method to record spontaneous retinal activity, without the use of a flash stimulus, that we named the resting-state ERG (rsERG).

AAV-mediated gene augmentation improves visual function in the PEX1-Gly844Asp mouse model for mild Zellweger spectrum disorder.

Patients with Zellweger spectrum disorder (ZSD) commonly present with vision loss due to mutations in genes required for peroxisome assembly and function. Here, we evaluate retinal gene augmentation therapy in a mouse model of mild ZSD bearing the murine equivalent (PEX1-p[Gly844Asp]) of the most common human mutation. Experimental adeno-associated virus 8.

Multi-Angular Electroretinography (maERG): Topographic Mapping of the Retinal Function Combining Real and Virtual Electrodes.

Goal: The full-field electroretinogram (ffERG) is an objective tool to assess global retinal function, though as it is currently done, it is unable to localize sources of retinal dysfunction or damage. To overcome this, we have developed a new way to record multiple spatial derivations of the ERG using the rotating capability of the eye, thus creating "virtual electrodes". We have termed this the multi-angular ERG (or maERG).

Organic visual loss measured by kinetic perimetry and retinal electrophysiology in children with functional amblyopia.

Purpose: To demonstrate an organic (retinal) amblyogenic defect in functional amblyopes not responding to treatment.

Methods: Twenty-four children (Mean age: 5.9 ± 1.

Functional alterations of retinal neurons and vascular involvement progress simultaneously in the Psammomys obesus model of diabetic retinopathy.

To investigate the progression of diabetic retinopathy (DR) in a new diurnal animal model, we monitored clinically the DR in Psammomys obesus (P. obesus) during 7 months using electroretinography (ERG) and imaging techniques. After the onset of DR, all ERG components decreased progressively.

Distinguishing Familial from Acquired Traits in the Retinal Blood Vessel Arborization.

Purpose: It has been suggested that retinal blood vessel arborization (RBVA) is unique to each individual. We examined this claim in a pedigree that included two pairs of monozygotic twins.

Methods: Fundus photographs were taken of subjects belonging to this pedigree to compare the pattern of their RBVA.

Ring analysis of multifocal oscillatory potentials (mfOPs) in cCSNB suggests near-normal ON-OFF pathways at the fovea only.

Purpose: To investigate the center-periphery distribution of ON and OFF retinal responses in complete congenital stationary night blindness (cCSNB).

Methods: Photopic full-field flash ERGs (photopic ffERGs) and OPs (photopic ffOPs) and slow m-sequence (to enhance OP prominence) mfERGs (and filtered mfOPs) evoked by a 37 hexagon stimulus array were recorded from normal subjects and cCSNB patients. Discrete wavelet transform (DWT) analysis of photopic ffERGs and mfERGs was also performed in order to assess the contribution of the ON and OFF retinal pathways (i.

mutant mice recapitulate neurological and ophthalmological abnormalities associated with 22q11 and CEDNIK syndrome.

Synaptosomal-associated protein 29 () encodes a member of the SNARE family of proteins implicated in numerous intracellular protein trafficking pathways. maps to the 22q11.2 region and is deleted in 90% of patients with 22q11.

A longitudinal study of retinopathy in the PEX1-Gly844Asp mouse model for mild Zellweger Spectrum Disorder.

Zellweger Spectrum Disorder (ZSD) is an autosomal recessive disease caused by mutations in any one of 13 PEX genes whose protein products are required for peroxisome assembly. Retinopathy leading to blindness is one of the major untreatable handicaps faced by patients with ZSD but is not well characterized, and the requirement for peroxisomes in retinal health is unknown. To address this, we examined the progression of retinopathy from 2 to 32 weeks of age in our murine model for the common human PEX1-p.

Evidences Suggesting that Distinct Immunological and Cellular Responses to Light Damage Distinguishes Juvenile and Adult Rat Retinas.

To unravel the mechanisms behind the higher resistance to light damage of juvenile (JR) versus adult (AR) rats, Sprague Dawley rats were exposed to a bright luminous environment of 10, 000 lux. The light-induced retinopathy (LIR) was assessed with histology, electroretinography and immunohistochemistry (IHC). In JR, 2 days of exposure induced the typical LIR, while >3 days added little LIR.

ISCEV extended protocol for the stimulus-response series for light-adapted full-field ERG.

The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum protocol for clinical testing but encourages additional ERG testing when appropriate. This ISCEV extended protocol describes methods to record and evaluate a light-adapted (LA) ERG stimulus-response series with increasing flash strengths. The LA ERG stimulus-response series (also referred to as the luminance-response or intensity-response series in the published literature) can characterise generalised cone system function more comprehensively than the ISCEV standard LA ERGs alone.

The effects of bandpass filtering on the oscillatory potentials of the electroretinogram.

Purpose: In order to study the OPs, the ERG signal must be filtered to eliminate the low-frequency waves known as the a- and b-waves. Unfortunately, the ISCEV ERG standard does not give clear guidelines on how to proceed apart from indicating that frequencies below 75 Hz should be filtered out when recording scotopic OPs, while no suggestions are offered for the photopic OPs. The purpose of this study was thus to characterize more extensively the effects of various digital filters on the photopic OP waveforms in order to suggest the most appropriate filtering method to record them.

Revealing a retinal facilitatory effect with the multifocal ERG.

Purpose: We have previously shown that the amplitude of the mfERG response obtained to a single (large) hexagon is significantly smaller than that obtained when summating all the mfERG responses evoked to an array of 7-61 hexagons covering the same retinal area. The purpose of this study was to confirm our initial findings in normal subjects of different ages and in selected patients.

Methods: Binocular mfERGs (1, 7, 19, 37 and 61 hexagon arrays; Espion V6.

Evaluating the neuroprotective effect of 17β-estradiol in rodent models of oxidative retinopathies.

Purpose: To determine the neuroprotective effect of estrogen on the structure and function of the retina exposed to an oxidative stress.

Methods: Male Sprague-Dawley rat pups were exposed to either hyperoxia (OE: from P8 to P14) or bright light (LE: from P14 to P28) with or without 17 β-estradiol (βE) treatment. Retinal structure (histology) and function (ERG) were assessed at selected time points.

Electroretinographic evidence suggesting that the type 2 diabetic retinopathy of the sand rat Psammomys obesus is comparable to that of humans.

Purpose: Type 2 diabetic retinopathy is the main cause of acquired blindness in adults. The aim of this work was to examine the retinal function of the sand rat Psammomys obesus as an animal model of diet-induced type 2 diabetes when subjected to a hypercaloric regimen.

Materials And Methods: Hyperglycemia was induced in Psammomys obesus by high caloric diet (4 kcal/g).

Recording and Analysis of the Human Clinical Electroretinogram.

The electroretinogram (ERG) represents the biopotential that is produced by the retina in response to a light stimulus. To date, it remains the best diagnostic tool to objectively evaluate the functional integrity of the normal or diseased retina. In the following pages we briefly review the necessary requirements in order to record and analyze the conventional clinical ERG.

The DTL ERG electrode comes in different shapes and sizes: Are they all good?

Purpose: Although the DTL fiber electrode has been in use in the ERG field for more than four decades, its composition was never clearly defined. We compared five different types of conductive (DTL type) yarn (differing in terms of mass, number of filaments, and crimping degree) in order to determine whether we could identify one that would be better suited for the recording of ERGs.

Methods: Photopic flash ERGs were recorded from five subjects using the following DTL electrodes: 27/7, 22/1, 11/1, 11/1*2, and 22/1*2.

Light-Induced Retinopathy: Young Age Protects more than Ocular Pigmentation.

Purpose: The purpose of this study was to compare the efficacy that ocular melanin confers in protecting the retina of juvenile and adult rats exposed to a bright luminous environment.

Methods: Juvenile (JLE) and adult (ALE) Long-Evans pigmented rats were thus exposed to a bright cyclic light (10,000lux; white light) from postnatal day 14-28 or for 6 consecutive days, respectively. Flash electroretinograms (ERG) and retinal histology were performed at different predetermined ages, post-light exposure.

Assessing the Contribution of the Oscillatory Potentials to the Genesis of the Photopic ERG with the Discrete Wavelet Transform.

The electroretinogram (ERG) is composed of slow (i.e., a-, b-waves) and fast (i.

Quantifying the ON and OFF Contributions to the Flash ERG with the Discrete Wavelet Transform.

Purpose: Discrete wavelet transform (DWT) analyses suggest that the 20- and 40-Hz components of the short-flash photopic electroretinogram (ERG) are closely related to the ON and OFF pathways, respectively. With the DWT, we examined how the ERG ON and OFF components are modulated by the stimulus intensity and/or duration.

Methods: Discrete wavelet transform descriptors (20, 40 Hz and 40:20-Hz ratio) were extracted from ERGs evoked to 25 combinations of flash durations (150-5 ms) and strengths (0.

Choroidal Involution Is Associated with a Progressive Degeneration of the Outer Retinal Function in a Model of Retinopathy of Prematurity: Early Role for IL-1β.

Retinopathy of prematurity (ROP), the most common cause of blindness in premature infants, has long been associated with inner retinal alterations. However, recent studies reveal outer retinal dysfunctions in patients formerly afflicted with ROP. We have recently demonstrated that choroidal involution occurs early in retinopathy.

Sildenafil Improves Functional and Structural Outcome of Retinal Injury Following Term Neonatal Hypoxia-Ischemia.

Purpose: The purpose of this study was to investigate the effects of sildenafil on retinal injury following neonatal hypoxia-ischemia (HI) at term-equivalent age in rat pups.

Methods: Hypoxia-ischemia was induced in male Long-Evans rat pups at postnatal day 10 (P10) by a left common carotid ligation followed by a 2-hour exposure to 8% oxygen. Sham-operated rats served as the control group.

Strain Differences in Light-Induced Retinopathy.

The purpose of this study was to better understand the role of ocular pigmentation and genetics in light-induced retinal damage. Adult pigmented [Long Evans (LE) and Brown Norway (BN)] and albino [Sprague Dawley (SD) and Lewis (LW)] rats were exposed to a bright cyclic light for 6 consecutive days and where compared with juvenile animals exposed to the same bright light environment from postnatal age 14 to 28. Flash ERGs and retinal histology were performed at predetermined days (D) post-light exposure.