A 2-second presaturation of the intense water contribution was also required. By using a recycling delay of 3. Corneas from control or treated groups were fixed with 3. The 4 different exposure conditions were randomized: Statistical comparisons were achieved using nonparametric tests. The spectra were apodized by using a 0. Baseline correction was also automatically realized. The final spectra were finally segmented in spectral bands of 0.
These bands were then statistically analyzed with SIMCA v12 Umetrics, Umea, Sweden ; a principal components analysis PCA was first performed to identify possible gathering data and unclassified aberrant criterions. This processing assumed that a given result to the sham or exposed groups was realistic. Observation of the periocular area and of the cornea did not show any inflammation, edema burns, or conjunctivitis in any case.
However, if no keratitis, corneal opacity, or traces of surgery were found, limited hazes were detected in two cases on exposed rabbits. Ophthalmoscope examination showed neither lens opacity nor eye floaters within the vitreous humor, meaning that there was no major cataract formation or vitreous degeneration. This examination was completed by light diffusion measurements of the lens, as shown in Figure 2. The standard deviation of each group shows an important dispersion of light scattering properties in the same group.
However, no significant difference was found between the four groups or between the exposed and sham-exposed groups after gathering the surgery and sham surgery groups, by using nonparametric tests Mann Whitney. Six months after surgery, the aspect of nonexposed operated corneas Figure 3 a has been restored, similar to control corneas Figure 3 b. One could only notice a fine colorful linear mark corresponding to the surgical scare and a slight thickening of the epithelium at the edge of the flap.
After six months of exposure, slight modifications of the epithelium were noticed. The epithelial aspect was less regular with limited proliferative areas Figure 3 c. The stroma and endothelium were not modified. When exposures were performed after surgery Figure 3 d , the proliferative areas were found to be more numerous, while the other tissues of the cornea, stroma, and endothelium appeared unmodified, as in the control groups.
The spectrum in Figure 4 is typical of the lipid extract of biological tissues, where different resonances can usually be easily attributed to different chemical groups [ 27 ].
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However, due to the poor signal-to-noise ratio and experimental time constraints, a statistical analysis could only be performed after having bucketed the spectra, as seen in the 13 C-NMR trace of Figure 4 a. Besides, some areas containing no meaningful resonance were discarded from analysis i. After area integration and normalization see methods , the 4 different classes were compared in pairs, as presented in Figure 4 b. The absence of any significant difference between groups and also great interindividual variability were drawn from the nonparametric analysis Kruskal Wallis and confirmed by the PLS-DA analysis, as observed in the correlation circle presented in Figure 4 c in the case of type 2 tests.
The histological analysis of cornea slices also failed to show any morphological difference at the tissue level. Despite several broad lipidic and macromolecular contributions especially around 1. However, due to the severe overlaps occurring in the 3. After a four-class analysis similar to that used in the previous section using paired KW tests, no significant difference was identified between the exposed versus sham classes, as shown in Figure 5 b.
Oxidative stress was assessed in the aqueous humor and in the plasma by measuring reserve in the overall remaining antioxidant capacity. The results are shown in Figure 6 and are expressed as the equivalent concentration of Trolox used to have the same antioxidant effect. Six months after surgery and following 5 months of chronic electromagnetic exposure, no significant difference was observed between groups either in the aqueous humor or in plasma. The PCA correlation circle shown in Figure 7 a was built using 8 main components.
Lipid Profiles of Lenses Extracts: The same experimental procedure was used as for cornea analysis.
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Here, however, the signal-to-noise ratio was sufficient to allow the identification of numerous peaks. Many of them identified by stars in Figure 8 a were related to cholesterol resonances.
For cholesterol contribution analysis, C5, C6, and C17 resonances were used located at , , and Here, also, no significant difference was found between groups taken separately by pairs or gathered in exposed versus sham groups. Figure 9 a shows the high-field part of the 1 H-NMR spectrum of aqueous humor obtained after lyophilization and resuspension in D 2 O. Such a spectrum looks very similar to those recorded for aqueous humors, whereas the magnitudes of the different metabolites were found to be in very different proportions.
The same analysis performed on these spectra evidenced no significant differences see for instance the histograms in Figure 9 b , while PLS-DA allowed no clear distinction between the different classes. The aim of this work was to investigate whether chronic electromagnetic field exposure of the eyes after keratotomy would influence healing or at least induce metabolic or structural modifications in the eyes.
Such an interrogation was supported by several professional situations, such as those for radar technicians and engineers in airports or navy personnel aboard warships. The question here was to determine whether radar exposure under chronic conditions at occupational power levels could lead to deleterious effects regarding cornea healing or metabolic perturbations in the different building blocks of the eyes.
The different experiments performed on the different parts of the eyes, cornea observations, analyses, and histology failed to find any significant effect. This was in strong agreement with papers underlining that significantly more intense power is requested to obtain cornea lesions [ 28 , 29 ]. The question was clearly less intuitive about the liquid media of the eyes, in the aqueous and vitreous humors, since only recent metabolic studies have been performed on these media, mainly using NMR methods, generally under well-identified deleterious situations such as diabetes [ 30 ], or UV exposure [ 17 ].
In such cases, soluble metabolite and lipidic analyses similarly showed no difference under radiofrequency exposure. The question was more subject to controversy in the case of lenses.
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On the one hand, there is no doubt today that microwave radiation via thermal effects may lead to cataracts. Hence, the international guidelines for exposure limits to microwave radiations were directly related to protection against thermal effects [ 9 ]. Former results with rabbits have shown [ 31 ] that the threshold intensity radiation for cataract formation under microwave exposure was about minutes at 2. Conversely, more recent works [ 11 ] have reported cataract induction when using longer exposure durations 8 days at lower power levels 0. In the work by Dovrat et al.
These results appeared very different from a local temperature increase, where bubbles are also created but appear more homogeneous and far from sutures. If no clear mechanism was identified, the author suggested that such effects could result from microscopic friction at the interface between two bundles of lens fibers causing a local temperature increase. One would notice that the SAR estimation was only extracted from the ratio of source power to eye weight 1.
Our study showed no difference between the sham groups and the exposed population and also no difference with time within one of these groups. Due to some limitations, extrapolation of that work to the human eye should be carefully considered.
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The main limitation could be addressed on the surgical operation itself. The experimental constraints do not allow the realization of photoablation in our model. However, ablation of the stromal bed could add great stress caused by the laser energy absorption. Moreover, the rabbit eye presents some differences to the human eye, such as corneal endothelium with replicative capacity, unlike in the human cornea.
All of those considerations lead to the potential underestimation of possible effects of human electromagnetic exposure. This paper dealt with the consequences of chronic electromagnetic exposures at occupational levels on the eyes after keratotomy. From the extensive study of all compartments of the eye using various approaches, including anatomy, histology, and NMR lipidic and metabolic analysis, as well as light diffusion, no dramatic deleterious effect was identified on eye healing or eye structure under these conditions.
This, for instance, would be based on variations of the power of exposure and duty cycles at very low levels or conversely at levels close to thermal effects. This work, involving numerous animals and long experimental periods, is currently in progress. The authors declare that there is no conflict of interests regarding the publication of this paper. Indexed in Science Citation Index Expanded. Subscribe to Table of Contents Alerts. Table of Contents Alerts. Abstract LASIK eye surgery has become a very common practice for myopic people, especially those in the military.
Introduction LASIK surgery is routinely used to correct refraction abnormalities, such as myopia, hypermetropia, or astigmatism, without wearing glasses or contact lenses [ 1 ]. Materials and Methods 2. Animal Experiments All procedures were in accordance with the standards for animal care established by the Army Biomedical Research Institute IRBA and were approved by the IRBA ethics committee for animal experimentations decree 19 October , edited by the French government.
Position A represents the light path through a normal lens, while position B represents the light path through a lens with diffraction abnormalities. The letter in formula column refers to the label of the peak of interest. Significance was determined using the Mann-Whitney U test. Buckets are represented by black boxes and identified, as used in statistical analyses a. Histogram representation of Kruskal-Wallis tests, using four classes: PLS-DA correlation circle for type two tests: Write a customer review. Amazon Giveaway allows you to run promotional giveaways in order to create buzz, reward your audience, and attract new followers and customers.
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