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AIM: To evaluate the changes in fundus parameters in patients with Alzheimer's type dementia (ATD) using optical coherence tomography angiography (OCTA), to record flash electroretinograms (ERG) using the RETeval system and to explore changes in retinal function. METHODS: Twenty-nine patients with ATD and 26 age-matched normal subjects were enrolled. All subjects underwent OCTA scans to analyse the superficial retinal vessel parameters in the macular area, including the vessel length density, the vessel perfusion density and the area of foveal avascular zone (FAZ), as well as the choroidal thickness. The differences between the patients with ATD and the normal control group were compared and explored the relevant factors affecting vessel parameters. We also recorded the flash ERGs using the RETeval system and intended to explore changes in retinal function by analysing the ERG image amplitude in patients with ATD. RESULTS: The vessel parameters [Pvessel length density=0.005 and Pvessel perfusion density=0.006) and average choroid thickness (P

Background Bardet–Biedl syndrome (BBS) is a very rare autosomal recessive genetic disease with multiple manifestations including the ocular system. Aim This study presents different electrophysiological and clinical findings in three female patients with BBS. Patients and methods 3 female patients (9, 10 and 16 years old) with BBS were complaining of progressive visual loss. Full ophthalmological examination, optical coherence tomography (OCT) and various electrophysiological tests were performed to the 3 cases. Results The fundoscopic findings in all three patients did not show evidence of obvious characteristic signs of retinitis pigmentosa. They presented clinically with atypical form of pigmentary retinal dystrophy. Flash electroretinogram showed severe form of Rod-cone dystrophy in the 3 cases associated with macular dysfunction evident by reduced amplitude and increased implicit time of P1 wave of the multifocal electroretinogram in all rings. The pattern electroretinogram was with poor formed P50 wave. Pattern visual evoked potential showed prolonged latency and reduced amplitude of P100 wave in large and small checks. Conclusion Very reduced flash and multifocal electroretinogram is a Characteristic electrophysiological finding in BBS, which may precede the funduscopic changes, electrophysiological tests may help in the early diagnosis of such cases.

Aim: Psychosis can be preceded by a clinical high risk for psychosis (CHR) and visual anomalies are predictors of transition to psychosis. Visual retinal processing is altered in psychosis, but no study has explored the links between visual symptoms and retinal functions in CHR patients. We report here the case of NR, an antipsychotic‐naive young adult with CHR and severe visual symptoms in whom we explored the retinal function. Methods: A flash electroretinogram (fERG) and a pattern electroretinogram (pERG) protocol were conducted and we compared NR results to a group of patients with schizophrenia and a group of healthy controls. Results: Despites an overlap between the measures of NR and the two groups, visual analyses revealed that NR showed increased b‐wave implicit time (rod response) compared to the control group and NR's response was at an intermediate level between two subgroups of schizophrenia patients regarding presence or absence of visual hallucinations. Discussion: The relevance of retinal dysfunctions as a marker of vulnerability for psychosis is discussed. [ABSTRACT FROM AUTHOR]

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.e., OFF-to-ON ratio) in both cohorts. Results: As expected, the photopic ffERG (and ffOPs) responses in cCSNB were devoid of the first two of the three OPs (i.e., OP2 and OP3 and OP4) normally seen on the ascending limb of the b-wave. A similar finding was also noted in the mfERGs (and mfOPs) of ring 4. In contrast, the mfERGs (and mfOPs) of ring 1 included all three OPs. DWT analysis revealed that while in normal subjects, the OFF-to-ON ratio of mfERGs slightly increased from rings 1 to 4 (from 0.61 ± 0.03 to 0.78 ± 0.04; p < 0.05; median: from 0.62 to 0.79; p < 0.05), in cCSNB this ratio increased significantly more [from 0.73 ± 0.13 (ring 1) to 1.18 ± 0.17 (ring 4); p < 0.05; median: 0.78 to 1.22; p < 0.05], hence from a normal ON-dominated ratio (central ring) to an OFF-dominated ratio (peripheral ring). Conclusions: Our results show a clear discrepancy of ON and OFF mfOP components in cCSNB. Responses originating from the most central ring (i.e., ring 1) disclosed a near-normal electrophysiological contribution (as revealed with the presence of OP2, OP3 and OP4 as well as with the DWT OFF-to-ON ratio) of the retinal ON and OFF pathways in mfERG (and mfOPs) responses compared to responses from the more peripheral ring (and ffOP) which are devoid of the ON OPs (i.e., OP2 and OP3). [ABSTRACT FROM AUTHOR]

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The electroretinogram has revealed photoreceptor, bipolar cell, and, in one prior study, retinal ganglion cell (RGC) dysfunction in schizophrenia. The structural abnormalities of the RGC are well documented in schizophrenia and such abnormalities have been associated with visual hallucinations (VH) in neurological disorders. The goals of this study were: 1) to examine the functional responses of photoreceptors and RGC in schizophrenia patients in comparison with healthy controls; and 2) to compare the extent of retinal dysfunction in schizophrenia patients with or without VH. We recorded the flash electroretinogram in scotopic and photopic conditions, and the pattern electroretinogram, in schizophrenia patients (n = 29) and healthy controls (n = 29). Schizophrenia patients were divided in two groups: schizophrenia patients with VH (VH group, n = 12) and schizophrenia patients with auditory hallucinations or no hallucinations (AHNH group, n = 17). Our results replicate previous findings regarding photoreceptor dysfunction in schizophrenia. PERG results showed a significant increase of the P50 implicit time in schizophrenia patients compared with controls (t(55) = 2.1, p < .05, d = 0.55) and a significant increase of the N95 implicit time in schizophrenia patients compared with controls (t(55) = 4.2; p < .001, d = 0.66). We found an increased rod b-wave implicit time (dark-adapted 0.01 ERG) in the VH group compared to the AHNH group and to the control group, which was associated with lifetime VH score. Our results demonstrate a slowing of RGC signaling in schizophrenia patients, which could affect the quality of visual information reaching the visual cortex. The implications of the data for understanding VH in schizophrenia are discussed. [ABSTRACT FROM AUTHOR]

Background Bardet-Biedl syndrome (BBS) is a very rare autosomal recessive genetic disease with multiple manifestations including the ocular system. Aim This study presents different electrophysiological and clinical findings in three female patients with BBS. Patients and methods 3 female patients (9, 10 and 16 years old) with BBS were complaining of progressive visual loss. Full ophthalmological examination, optical coherence tomography (OCT) and various electrophysiological tests were performed to the 3 cases. Results The fundoscopic findings in all three patients did not show evidence of obvious characteristic signs of retinitis pigmentosa. They presented clinically with atypical form of pigmentary retinal dystrophy. Flash electroretinogram showed severe form of Rod-cone dystrophy in the 3 cases associated with macular dysfunction evident by reduced amplitude and increased implicit time of P1 wave of the multifocal electroretinogram in all rings. The pattern electroretinogram was with poor formed P50 wave. Pattern visual evoked potential showed prolonged latency and reduced amplitude of P100 wave in large and small checks. Conclusion Very reduced flash and multifocal electroretinogram is a Characteristic electrophysiological finding in BBS, which may precede the funduscopic changes, electrophysiological tests may help in the early diagnosis of such cases. [ABSTRACT FROM AUTHOR]

Retinitis pigmentosa (RP) is a pathological condition leading to progressive visual decline resulting from continual loss of photoreceptor cells and outer nuclear layers of the retina. The aim of the present study was to explore whether melanopsin was able to restore retinal function and inhibit its degeneration by acting in a similar manner to channel rhodopsins. Royal College of Surgeons rats, which were used as an animal model of inherited retinal degeneration, were subjected to sub-retinal injection with melanopsin overexpression vector (AV-OPN4-GFP). Immunohistochemical and western blot analyses were used to detect the distribution and protein expression of melanopsin in the retina, revealing that melanopsin was gradually reduced with increasing age of the rats, which was due to loss of dendritic axons of intrinsically photosensitive retinal ganglion cells. Animals injected into both eyes were subjected to a behavioral open-field test, revealing that melanopsin overexpression reduced the loss of light sensitivity of the rats. In a flash electroretinography experiment, the b-wave and response to light flash stimuli at three and five weeks following injection with AV-OPN4-GFP were higher compared to those in eyes injected with AV-GFP (P<0.05). In conclusion, the present study showed that during retinal degeneration, the expression of melanopsin was significantly decreased, while vector-mediated overexpression of melanopsin delayed the loss of visual function in rats. [ABSTRACT FROM AUTHOR]

Abstract Purpose The goal of our study was the evaluation of a practical method for the recording of flash electroretinograms (ERGs) in sedated, standing horses with the DTL™ microfiber electrode. Methods The horses were sedated intravenously with detomidine hydrochloride (0.015 mg/kg). The pupil was dilated and the auriculopalpebral nerve was blocked. The ERGs were recorded with the active electrode on the cornea (DTL™), the reference electrode near the lateral canthus, and the ground electrode over the occipital bone. The light intensities of the white strobe light were 0.03 cd·s/m2 (scotopic) and 3 cd·s/m2 (scotopic and photopic). Photopic and scotopic single flash and flicker responses to Ganzfeld stimulation were recorded. During the 20-min dark adaptation period the retina was stimulated every 5 min with the 0.03 cd·s/m2 single flash. Results The median b-wave amplitudes and implicit times were 38 µV and 33 ms (photopic cone-dominated response), 43 µV and 63 ms (5-min dark adaptation), 72 µV and 89 ms (10 min), 147 µV and 103 ms (15 min), 188 µV and 109 ms (20 min, 0.03 cd·s/m2 , rod response), and 186 µV and 77 ms (20 min, 3 cd·s/m2 , maximal combined rod-cone response). A steady increase in amplitude and implicit time was noted during dark adaptation. No oscillatory potentials could be isolated. Conclusions The use of detomidine hydrochloride sedation and the DTL™ microfiber electrode allowed the recording of good quality ERGs. This protocol should permit the detection of functional problems in the retina without the risk involved with general anesthesia. [ABSTRACT FROM AUTHOR]

Evaluates the inner plexiform layer of the retina by examining the oscillatory potentials (OP) of the flash electroretinogram (fERG) in older people. Assessment of fERG and OP on scotopic conditions; Pattern of visual impairments; Effect of normal aging on OP through electroretinographic recordings.

Electrophysiological tests (electroretinogram, oscillatory potentials, visual evoked potentials, in the basal condition and after photostress) reveal an abnormal function of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess whether electrophysiological abnormalities in visual function exist in newly-diagnosed diabetic patients free of any fluorangiographic signs of retinopathy. Ten control subjects (age 28.7±2.44 years) and ten IDDM patients (age 25.2±6.78 years; disease duration 5.3±3.5 months) in stable metabolic control (HbA7.5±1.1%) were evaluated. Flash-electroretinograms and oscillatory potentials were similar in both groups. Visual evoked potentials (VEP) recorded under basal conditions showed that P100 latency was significantly increased in the diabetic patients compared to control subjects ( p < 0.01), while N75-P100 amplitude was similar in both groups. The recovery time of VEP after photo-stress was equivalent in diabetic patients and control subjects. The impaired basal VEPs suggest an early involvement of the nervous conduction in the optic nerve. However, the preserved flash-electroretino-gram and the normal recovery time after photostress indicate that a short disease duration does not induce physiopathological changes in the outer retinal layers or in the macular function. [ABSTRACT FROM AUTHOR]