Mm In Light Research Articles

Comparative Analysis of Pupil Diameters in Light and Dark Conditions After Instillation of 0.15% Brimonidine Drops in Eyes With and Without Pseudoexfoliation Syndrome.

Objectives:This study aimed to compare pupil diameters in light and dark conditions after instillation of 0.15% brimonidine drops in eyes with and without pseudoexfoliation syndrome (PES).Methods:Forty eyes of 40 patients in whom 0.15% brimonidine drops were instilled to their right eyes between March 2019 and June 2019 were analyzed in this study. Study groups included 20 subjects without PES (group 1) and 20 patients with PES (group 2). Pupil diameters before and 30 and 90 min after brimonidine application were recorded and analyzed.Results:In group 1, the mean pupil diameters before brimonidine drop instillation were 4.8±1.2 mm and 5.8±1.2 mm in light and dark conditions, respectively, while those in group 2 were 4.4±1.2 mm and 4.9±1.3 mm, respectively. At 30 min after brimonidine drop instillation, the pupil diameters in light and dark conditions were 4.3±1.1 mm and 5.3±1.0 mm in group 1 and 4.1±1.1 mm and 4.5±1 mm in group 2, respectively. In group 1, the mean pupil diameters at 90 min were 4.2±1.1 mm and 5.1±1.1 mm in light and dark, respectively, and in group 2, they were 4.0±1.1 mm and 4.4±1.2 mm, respectively. In the dark, the pupil diameters before drop instillation were significantly smaller in group 2 than in group 1 (p≤0.05). A significant difference was found between the groups with respect to the measurements in the dark at 30 min (p≤0.05). When the differences at 30 and 90 min and the initial pupil diameters in light condition were compared between the groups, the change in the pupil diameter at 30 min was statistically significant (p≤0.05). At 90 min, differences in both light and dark measurements were statistically significant (p≤0.05).Conclusion:Brimonidine causes significant miosis in eyes with PES compared with eyes without PES. Brimonidine may have positive effects on spherical aberrations, glares, and halos. However, inadequate pupillary dilation may make it more difficult to perform cataract surgery and may further increase the complication rate.

Exceptions that Prove the Rules in Neuro-Ophthalmology

Exceptions that Prove the Rules in Neuro-Ophthalmology

Role of Surface Adsorbed Anionic Species in Antibacterial Activity of ZnO Quantum Dots Against <I>Escherichia coli</I>

We have studied the role of surface bound anionic species on zinc oxide (ZnO) quantum dots (QDs) for the antibacterial activity against Escherichia coli (E. coli) bacteria. The ZnO QDs with surface adsorbed anionic species of acetate ions and nitrate ions have been synthesized using wet chemical route. X-Ray diffraction studies reveal single-phase hexagonal wurtzite structure of as synthesized ZnO QDs. The particle size was found to be 3-5 nm for acetate adsorbed ZnO QDs and 4-7 nm for nitrate adsorbed ZnO QDs. Minimum inhibitory concentration (MIC) measurements and growth kinetics studies for E-coli show a marked difference in the antibacterial activity of ZnO QDs with both anionic species. The MIC for acetate adsorbed ZnO QDs was found to be 2.5 mM in light and 3 mM in dark. However, nitrate adsorbed ZnO QDs exhibits MIC about 6 mM in light and no significant bacterial growth inhibition was observed upto 30 mM under dark. The enhanced bacterial growth inhibition observed for acetate adsorbed ZnO QDs is attributed to the inherent ability of acetate ions to generate reactive oxygen species. The acetate adsorbed QDs having excellent antibacterial activities suggests its potential application for practical bactericidal realization.

A case of Pourfour du Petit syndrome following tumour surgery of the mandible

A 15-year-old male patient was referred to our eye clinic due to a sudden postoperative anisocoria after removal of a myxofibroma on the right side of the mandible on the...

Microscale investigations of microbial communities in coastal surficial sediments

AbstractThe upper millimeters of sediments are considered major locations of microbial colonization and activity. The goal of our study was to investigate variations of microbial communities in the uppermost sediment layers of the coastal Baltic Sea with emphasis on the complex interplay between microbiology and physico‐chemical sediment properties. We selected a high‐resolution methodological approach that combined the cryolanding sampling technique (spatial resolution of 250 μm) with microsensor‐, spectrophotometric and microscopic analyses. While the oxygen penetration depths in dark conditions ranged from 1.4 mm to 2.6 mm during the study period, this zone expanded by about 1 mm in light and could be divided into three micro‐horizons: (i) an upper zone with a high net O2 production, (ii) an intermediate zone with increased O2 consumption on account of light‐stimulated respiration and (iii) a lower zone with lower O2 consumption. Time‐series experiments revealed a rapid response of the benthic microbial community to altered light intensities. In May and July, the net O2 budget in the porewater of sediments was positive within 35 and 22 min after illumination, respectively, whereas in June O2 production exceeded O2 consumption after 112 min. The thickness of the O2 production and O2 consumption micro‐zones decreased from May to July coinciding with an increase in temperature. In May, sites of enhanced O2 consumption were closely associated with subsurface maxima of microbial numbers and enzymatic activities indicating a tight coupling between photoautotrophic and heterotrophic processes between 1‐ and 2‐mm depth. In June and July, the microbial abundance and enzymatic activity hardly varied with depth. Spatial and temporal microheterogeneity of microbial distribution and activity in O2 gradients was seen as a reflection of the complex interplay between microbiology and physico‐chemical sediment properties.

Bio-optical Characteristics and the Vertical Distribution of Photosynthetic Pigments and Photosynthesis in an Artificial Cyanobacterial Mat.

Zonations of photosynthesis and photopigments in artificial cyanobacterial mats were studied with (i) oxygen and pH microsensors, (ii) fiber-optic microprobes for field radiance, scalar irradiance, and PSII fluorescence, and (iii) a light microscope equipped with a spectrometer for spectral absorbance and fluorescence measurements. Our analysis revealed the presence of several distinct 1-2 mm thick cyanobacterial layers mixed with patches of anoxygenic photosynthetic bacteria. Strong attenuation of visible light confined the euphotic zone to the uppermost 3 mm of the mat, where oxygen levels of 3-4 times air saturation and a pH peak of up to pH 8.8 were observed under saturating irradiance (413 µmol photon m(-2) s(-1)). Oxygen penetration was 5 mm in light and decreased to 1 mm in darkness. Volumetric oxygen consumption in the photic and aphotic zones of illuminated mat was 5.5 and 2.9 times higher, respectively, than oxygen consumption in dark incubated mats. Scalar irradiance reached 100-150% of incident irradiance in the upper 0.5 mm of the mat due to intense scattering in the matrix of cells, exopolymers, and carbonate precipitates. In deeper mat layers scalar irradiance decreased nearly exponentially, and highest attenuation coefficients of 6-7 mm(-1) were found in cyanobacterial layers, where photosynthesis and photopigment fluorescence also peaked. Visible light was attenuated >100 times more strongly than near infrared light. Microscope spectrometry on thin sections of mats allowed detailed spectral absorbance and fluorescence measurements at defined positions relative to the mat surface. Besides strong spectral signals of cyanobacterial photopigments (Chl a and phycobiliproteins), the presence of both green and purple photosynthetic bacteria was evident from spectral signals of Bchl a and Bchl c. Microprofiles of photopigment absorbance correlated well with microdistributions of phototrophs determined in an accompanying study.