Photopic
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Fotopické ERG vyšetření jsme provedli podle mezinárodního standardu u 82 diabetiků. Zaznamenali jsme významnou redukci amplitud vlny b ve skupině 38 nemocných, kteří v době vyšetření neměli na očním pozadí ještě žádné patologické změny. Regresní analýza neprokázala u pacientů po laserové fotokoagulaci na rozdíl od kontrolní skupiny a diabetiků s prostou diabetickou retinopatií žádnou korelaci mezi věkem nemocných a velikostí retinálních odpovědí. Fotopické elektroretinogramy patří do elektrofyziologického diagnostického arzenálu u diabetu.
The authors made photopic ERG examinations according to the international standard in 82 diabetic patients. They recorded a significant reduction of ampli- tudes of the b wave in a group of 38 patients who at the time of the examination did not have yet any pathological changes on the fundus. Regressive analysis did not prove after laser photocoagulation in these patients, contrary to a control groupanddiabetic patients withsimple diabetic retinopathy, any correlation between the patients age and the extent of the retinal response. Photopic electroretinograms must be included in the electrophysiological dia- gnostic arsenal in diabetes.
In the present study, we asked whether contour interaction undergoes significant changes for different luminance levels in the central and peripheral visual field. This study included nine normal observers at two laboratories (five at Palacky University Olomouc, Czech Republic and four at the University of Houston, USA). Observers viewed a randomly selected Sloan letter surrounded by four equally spaced bars for several separations measured edge-to-edge in min arc. Stimuli were viewed foveally under photopic and mesopic luminances and between 5° and 12° peripherally for four different background luminances of the display monitors, corresponding to photopic, mesopic, scotopic, and dim scotopic levels. The extent of the contour interaction in the fovea is approximately 20 times smaller than in the periphery. Whereas the magnitude of foveal contour interaction markedly decreases with decreasing luminance, no consistent luminance-induced change occurs in peripheral contour interaction. The extent of contour interaction does not scale with the size of the target letter, either in the fovea or peripherally. The results support a neural origin of contour interaction consistent with the properties of center-surround antagonism.
- MeSH
- dospělí MeSH
- fovea centralis MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- noční vidění fyziologie MeSH
- rozpoznávání obrazu fyziologie MeSH
- senioři MeSH
- světelná stimulace MeSH
- vidění barevné fyziologie MeSH
- zraková pole MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
We have reported the gateway reflex, which describes specific neural activations that regulate immune cell gateways at specific blood vessels in the central nervous system (CNS). Four types of gateway reflexes exist, all of which induce alterations in endothelial cells at specific vessels of the blood-brain barrier followed by inflammation in the CNS in the presence of CNS-autoreactive T cells. Here we report a new gateway reflex that suppresses the development of retinal inflammation by using an autoreactive T cell-mediated ocular inflammation model. Exposure to photopic light down-regulated the adrenoceptor pathway to attenuate ocular inflammation by suppressing breaching of the blood-retina barrier. Mechanistic analysis showed that exposure to photopic light down-regulates the expression of α1A-adrenoceptor (α1AAR) due to high levels of norepinephrine and epinephrine, subsequently suppressing inflammation. Surgical ablation of the superior cervical ganglion (SCG) did not negate the protective effect of photopic light, suggesting the involvement of retinal noradrenergic neurons rather than sympathetic neurons from the SCG. Blockade of α1AAR signaling under mesopic light recapitulated the protective effect of photopic light. Thus, targeting regional adrenoceptor signaling might represent a novel therapeutic strategy for autoimmune diseases including those that affect organs separated by barriers such as the CNS and eyes.
- MeSH
- adrenalin metabolismus MeSH
- adrenergní látky metabolismus MeSH
- adrenergní receptory metabolismus MeSH
- alfa-1-adrenergní receptory metabolismus MeSH
- autoimunita genetika fyziologie MeSH
- autoimunitní nemoci imunologie MeSH
- centrální nervový systém metabolismus MeSH
- endoteliální buňky metabolismus MeSH
- ganglion cervicale superius metabolismus MeSH
- hematoencefalická bariéra metabolismus MeSH
- hematoretinální bariéra metabolismus MeSH
- myši inbrední BALB C MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- neurony metabolismus MeSH
- noradrenalin metabolismus MeSH
- retinitida patofyziologie MeSH
- světlo MeSH
- T-lymfocyty imunologie MeSH
- vidění barevné fyziologie MeSH
- zánět metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
SIGNIFICANCE: Both foveal and peripheral contour interactions are based on, as yet, unexplained neural mechanisms. Our results show that, unlike foveal contour interaction, peripheral contour interaction cannot be explained on the basis of the antagonistic structure of neural receptive fields. PURPOSE: Foveal contour interaction is markedly reduced for mesopic compared with photopic targets. This finding is consistent with an explanation based on the antagonistic structure of neural receptive fields. However, no reduction was found for low-luminance targets in the periphery, possibly because the luminances used previously remained substantially above peripheral scotopic detection thresholds. In this study, we compared foveal and peripheral contour interactions for long-wavelength photopic and mesopic targets, which would be expected to significantly elevate the peripheral retinal detection threshold. METHODS: Five normal observers viewed a randomly selected Sloan letter surrounded by four flanking bars at several edge-to-edge separations (min arc). Photopic and mesopic stimuli were viewed foveally and at 6° peripherally through a selective red filter that ensured that mesopic targets were within 1 log unit of detection threshold at both retinal locations. RESULTS: Whereas the magnitude of foveal contour interaction was substantially less at mesopic compared with photopic luminance (20 vs. 46% reduction of percent correct, on average), no significant difference was observed in peripheral contour interaction, which had average mesopic and photopic magnitudes of 38 and 40%. Moreover, confusion matrices representing photopic and mesopic contour interaction differed in the fovea but not in the periphery. The extent of contour interaction did not change with luminance at either retinal location. CONCLUSIONS: Our results indicate that, although the characteristics of foveal contour interaction can be accounted for by the antagonistic structure of neural receptive fields, the same mechanism is not compatible with the characteristics of peripheral contour interaction.
- MeSH
- dospělí MeSH
- fovea centralis fyziologie MeSH
- lidé MeSH
- senzorické prahy fyziologie MeSH
- světlo MeSH
- vidění barevné fyziologie MeSH
- vnímání tvaru fyziologie MeSH
- zraková pole fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
PURPOSE: The decrease in visual acuity under low luminance conditions is well known. Recent laboratory evidence showed that crowding under low luminance (mesopic) light levels is less robust than under photopic conditions. The present study examines whether such differences in crowding influence clinical measurements of mesopic visual acuity, including test-retest repeatability. METHODS: Twenty adult subjects with normal or corrected to normal visual acuity were recruited for the study. Monocular visual acuity was measured under photopic (228 cd/m2) and mesopic (0.164 cd/m2) luminance conditions using a letter chart, similar in principle to the ETDRS logMAR chart, presented on a computer monitor. Three rows of five letters, each row differing in size by 0.05 logMAR from largest to smallest were displayed at the center of the monitor. The level of crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50, 20, and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters, until three or more errors on the middle row were made. Each correctly identified letter contributed 0.01 to the recorded logMAR score. All measurements were repeated for each subject on two separate days. RESULTS: Visual acuity (logMAR) was significantly better under photopic than mesopic luminance conditions with a mean difference of 0.48 logMAR. Visual acuity also decreased with decreasing letter separation (i.e. increase in crowding). However, the decrease in visual acuity for the smallest letter separation was less under the mesopic luminance condition, even after accounting for the increased size of threshold acuity letters. Test-retest repeatability for mesopic and photopic conditions was not significantly different. CONCLUSIONS: Crowding under mesopic luminance conditions has less impact on visual acuity than under photopic luminance.
- MeSH
- citlivost na kontrast MeSH
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- referenční hodnoty MeSH
- světelná stimulace MeSH
- vidění barevné fyziologie MeSH
- vidění mezopické fyziologie MeSH
- zraková ostrost * MeSH
- zrakové testy metody MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
