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
SIGNIFICANCE: Contour interaction describes an impairment of visual acuity produced by nearby flanking features, which exerts a significant impact in many clinical tests of visual acuity. Our results indicate that the magnitude of interaction depends either on the flanker contrast energy (i.e., the product of flanker contrast and width) or the flanker contrast alone, depending on the contrast energy of the flankers. PURPOSE: The discrimination of acuity targets is impaired by the presence of nearby flanking contours, a phenomenon known as contour interaction. METHODS: In this study, we measured percent correct identification for threshold size, high-contrast Sloan letters at the fovea and at 5° in the inferior visual field for different combinations of flanking-bar width, and Weber contrast corresponding to specific fixed values of contrast energy (width × contrast, in %-min arc). RESULTS: For flanking bars with low-contrast energy, contour interaction exhibited no systematic dependence on the flanking-bar width. However, when the flanking bars had higher contrast energy, narrower high-contrast bars produced significantly greater contour interaction than wider bars of lower contrast. CONCLUSIONS: The results are consistent with the interpretation that contour interaction depends primarily on the contrast energy of flanking contours when their contrast energy is low. As the contrast energy of the flanking contours increases, the magnitude of contour interaction depends on the flanker contrast. For high-contrast flanking contours, the magnitude of contour interaction saturates when the width of the flanking contours is approximately 20% of letter size.
- MeSH
- citlivost na kontrast fyziologie MeSH
- dospělí MeSH
- fovea centralis MeSH
- lidé středního věku MeSH
- lidé MeSH
- senioři MeSH
- vnímání tvaru fyziologie MeSH
- zraková ostrost fyziologie MeSH
- zraková pole fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
SIGNIFICANCE: The main aim of this study was to determine the intraocular pressure (IOP) response to maximal incremental running test during 30 minutes of recovery. Exhaustive exercise induced a highly individually variable IOP response, which was related to its initial value and the initial heart rate. PURPOSE: The purpose of the study was to analyzed the IOP response to a maximal incremental running test in healthy women during a 30-minute recovery period. Secondarily, the study attempted to determine if the IOP was dependent on its baseline, maximal oxygen uptake, initial heart rate, and autonomic nervous system regulation. METHODS: Twenty-four healthy women between the ages of 19 and 30 years were recruited for the study. Initial IOP (baseline), heart rate, and autonomic nervous system regulation were measured after 30 minutes of rest. Each subject then underwent an incremental running test on a treadmill to reach the maximal physical activity and to determine physical fitness based on maximal oxygen uptake. Intraocular pressure and autonomic nervous system activity were measured immediately after completion of the physical activity during a 30-minute recovery period in the supine position. RESULTS: The IOP variability increased markedly after the exercise up to 1.7-fold of the resting state. The IOP before and after exercise did not differ significantly; however, the lower baseline revealed a significant increase in comparison with the higher baseline. The time course of the IOP changes was significantly influenced by the initial heart rate. All other effects, interactions, and correlations were insignificant. CONCLUSIONS: The IOP response after maximal exercise was highly dependent on the individual. The IOP seems to be slightly increasing with a significant dependence on its resting baseline and initial heart rate.
- MeSH
- běh fyziologie MeSH
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- nitrooční tlak fyziologie MeSH
- obnova funkce MeSH
- spotřeba kyslíku fyziologie MeSH
- srdeční frekvence fyziologie MeSH
- tonometrie oční MeSH
- zátěžový test MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: The aim of the study was to evaluate intraocular pressure (IOP) before and after moderate exercise in normal healthy individuals with defined physical exertion. The second aim of this investigation was to determine the correlation between resting IOP (IOPr) and its change induced by exercise as well as the relationship between resting heart rate (HRr) and changes in IOP after exercise. METHODS: Forty-one healthy volunteers between the ages of 19 and 25 years were recruited for the study. First, the resting (reference) values IOPr and HRr were measured after 30 min of resting time. Volunteers consequently performed 30 min of exercise on a bicycle ergometer. Intraocular pressure was remeasured immediately after the end of exercise (the relevant IOP change was denoted as ΔIOP0) and subsequently repeated 5, 10, 20, and 30 min after exercise. RESULTS: A significant decrease in IOP compared with the resting value (post hoc Tukey honest significant difference test) was found immediately after exercise (p = 2 × 10) and 5 and 10 min after exercise (p = 2 × 10 and p = 3 × 10). Significant relationships were found between the change in IOP (ΔIOP0) and baseline IOP (IOPr) and between the baseline resting heart rate (HRr) and the change in IOP (ΔIOP0). CONCLUSIONS: There was a significant IOP-lowering effect, which was persistent for 10 min after 30 min of exercise. The IOP change was dependent on the initial IOP reading and initial HR.
- MeSH
- cvičení fyziologie MeSH
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- nitrooční tlak fyziologie MeSH
- obnova funkce fyziologie MeSH
- srdeční frekvence fyziologie MeSH
- tonometrie oční MeSH
- zátěžový test MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: To demonstrate the use of in vivo corneal confocal microscopy to reveal the reason for persistent disturbance of vision after a corneal abrasion. CASE REPORT: A 49-year-old man presented with a decrease in visual acuity and monocular diplopia after a traumatic corneal abrasion. Anterior segment optical coherence tomography was not beneficial. In vivo corneal confocal microscopy showed abnormal folding in the basal epithelial layer of the cornea. Based on these findings, a therapeutic abrasion of the affected epithelium was performed. Visual acuity returned to 1.0 after therapeutic abrasion, and overall findings on the eye were within physiological limits. Control corneal confocal microscopic examination confirmed reparation of the structure of epithelial cell layers. CONCLUSIONS: The in vivo corneal confocal microscopy can reveal corneal pathologic abnormality even in cases where other methods are not beneficial. Alongside other modern methods, it may become an important tool to help locate pathologic abnormality accurately and choose the proper therapeutic strategy.
- MeSH
- debridement MeSH
- hojení ran fyziologie MeSH
- konfokální mikroskopie * MeSH
- lidé středního věku MeSH
- lidé MeSH
- optická koherentní tomografie MeSH
- poranění oka diagnóza etiologie patofyziologie chirurgie MeSH
- poruchy zraku diagnóza etiologie patofyziologie MeSH
- rohovkový epitel zranění patologie MeSH
- tupá poranění diagnóza etiologie patofyziologie chirurgie MeSH
- zraková ostrost fyziologie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
PURPOSE: To demonstrate and analyze the fifth-order theory of oblique astigmatism of a thin spherical spectacle lens and make a comparison with the third-order theory and exact ray tracing. METHODS: Fifth-order equations were derived and used for analysis of oblique astigmatism of a spherical spectacle lens to calculate analytically the shape of the lens with corrected oblique astigmatism for large angles of field of view. These results were compared with those of finite ray tracing and the third-order aberration theory. RESULTS: Formulas for the calculation of oblique astigmatism of a thin spherical spectacle lens were derived. These formulas analytically express oblique astigmatism of the third and fifth order. The theory presented generalizes the third-order description of astigmatism of the spherical spectacle lens and derived equations enable calculation of the shape of the spectacle lens with corrected astigmatism even for a large field of view. The fifth-order solution is compared with the third-order theory and the exact solution found by ray tracing. Differences between the third- and fifth-order theory are <0.05 D for spherical lenses, which is negligible clinically. CONCLUSIONS: The presented fifth-order equations, which are a generalization of the third-order formulas for the description of oblique astigmatism, can be used for the analytical expression of the fifth-order astigmatism of the spherical lens. They can simply be applied for the initial design of lenses with corrected astigmatism for large angles of view, something not possible using the third-order theory. We conclude that astigmatism of the fifth order has little effect on the image quality of the spectacle lens, and the third-order theory is satisfactory for practical calculations in optometry.
- MeSH
- astigmatismus patofyziologie terapie MeSH
- brýle normy MeSH
- design vybavení MeSH
- lidé MeSH
- optometrie metody MeSH
- refrakce oka fyziologie MeSH
- teoretické modely MeSH
- zraková pole fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
