Search results for "AOC"
showing 10 items of 504 documents
Synthesis of linear polyglycerols with tailored degree of methylation by copolymerization and the effect on thermorheological behavior
2017
Abstract We introduce a two-step strategy for the synthesis of linear polyglycerols (linPG-OHx/OMey) with an adjustable degree of methylation ( y = D M 100 ). Ethoxy ethyl glycidyl ether (EEGE) and glycidyl methyl ether (GME) were copolymerized via the “activated monomer” polymerization technique, using tetraoctylammonium bromide (NOct4Br) as an initiator and triisobutylaluminum (i-Bu3Al) as a catalyst under mild conditions. Subsequent acidic cleavage of the acetal protective groups generates linear polyglycerols with different degree of methylation (DM) by varying the GME comonomer content between 10 and 91%. Size exclusion chromatography (SEC) evidenced good control over molecular weight …
A Challenging Comonomer Pair: Copolymerization of Ethylene Oxide and Glycidyl Methyl Ether to Thermoresponsive Polyethers
2014
Motivated by the oxygen-rich and fully amorphous structure of poly(glycidyl methyl ether) (PGME), a series of thermoresponsive poly(glycidyl methyl ether-co-ethylene oxide) copolymers P(GME-co-EO) with molecular weights in the range of 3000–20 000 g mol–1 were synthesized by the activated monomer polymerization technique. Tetraoctylammonium bromide (NOct4Br) was employed as an initiator in combination with triisobutylaluminum (i-Bu3Al) as a catalyst under mild conditions. Polyethers with varying GME content between 31 and 100 mol % were obtained. Triad sequence analysis using 13C NMR spectroscopy proved that no pronounced block structure was obtained. Differential scanning calorimetry (DSC)…
Epicyanohydrin: Polymerization by Monomer Activation Gives Access to Nitrile-, Amino-, and Carboxyl-Functional Poly(ethylene glycol)
2015
Both homo- and copolymerization of the hitherto nonpolymerizable epoxide monomer epicyanohydrin (EPICH) with ethylene oxide (EO) have been studied, employing the monomer activation technique. Tetraoctylammonium bromide or tetrabutylammonium iodide was used as initiator combined with i-Bu3Al to activate the EPICH monomer. The EPICH content was varied from 4 to 16 mol %, yielding well-defined PEG-co-PEPICH copolymers with molecular weights Mn (SEC) ranging from 3700 to 8800 g mol–1. The nitrile groups of the resulting polyethers were further reduced or hydrolyzed to introduce amino, amide, or carboxyl groups at the polyether backbone, circumventing protecting group chemistry. Successful trans…
Transient reduction of the ocular perfusion pressure and the oscillatory potentials of the ERG
2005
Abstract Purpose. To evaluate the changes of the Oscillatory Potentials (OPs) of Electroretinogram (ERG) caused by short-term hypertension in human subjects, and their relationship with ocular perfusion pressure (OPP). Methods. Suction cup technique in 12 normal volunteers with OPs simultaneously recording. Results. Scotopic and photopic OPs were altered during OPP drop. Scotopic OPs showed more sensitiveness, with higher reduction (from 21% to 47%), when compared to the basal value, than in photopic recordings (from 14% to 34%). In both conditions, the relationship between OPP and OPs presented a steady amplitude before the trough after the +30 step, and rapid recovery after OPP normalisat…
Correlation of Crystallin Expression and RGC Susceptibility in Experimental Glaucoma Rats of Different Ages.
2018
Glaucoma is one of the leading causes of blindness worldwide with age being an important risk factor. However, the pathogenesis remains poorly understood. Aim of this study was to focus on age-dependent molecular changes in an experimental animal model of glaucoma.Intraocular pressure was elevated in Sprague-Dawley rats aged 3, 14, and 47 weeks for a period of 7 weeks by episcleral vein cauterization. Ganglion cell loss was monitored by an immunohistochemical staining of the Brain-specific homeobox/POU (Pit-1, Oct-2, Unc-86) domain protein 3A positive cells in retinal flat-mounts and spectral-domain optical coherence tomography measuring the retinal nerve fiber layer thickness. Molecular pr…
Biomarkers for glaucoma: from the lab to the clinic
2017
Glaucoma, a leading cause of irreversible blindness worldwide, is often not diagnosed until many years after disease onset. Early and objective diagnostic measures are yet missing. Besides the main risk factor, an elevated intraocular pressure (IOP), age, sex, and ethnicity are known to affect disease progression and severity. Furthermore, oxidative stress, elevated glutamate concentrations, and an autoimmune component are considered possible risk factors. We could identify several potential proteomic biomarkers in glaucoma and examine distinct changes in the glaucomatous human retina proteome. Using an experimental autoimmune glaucoma animal (EAG) model we could demonstrate an IOP-independ…
Phake Intraokularlinsen
2004
Phakic intraocular lenses (PIOLs), which are located closer to the eye's nodal points than the anterior corneal surface, can provide superior optical quality for higher corrections because of retention of normal prolate corneal asphericity and larger effective optical zones. Improvements in the material and design of phakic intraocular lenses and their insertion devices combined with advances in the understanding of the anatomical and physiological interactions of the PIOLs with intraocular structures, have increased safety and efficacy. Safety of these implants over the long term remains a concern, but in several situations PIOLs are the refractive correction of choice. The purpose of this…
Trifocal toric intraocular lenses in eyes with low amount of corneal astigmatism.
2020
Aim To evaluate the refractive and visual outcomes following cataract surgery and implantation of a trifocal toric intraocular lens (IOL) in eyes with low degrees of corneal astigmatism. Methods Twenty-six eyes of 22 patients who underwent implantation a trifocal toric IOL (FineVision PODFT, PhysIOL s.a., Liege, Belgium) were enrolled. Phacoemulsification with femtosecond laser, capsular tension ring insertion and intraoperative aberrometry were performed in all cases. All IOLs used showed a cylinder power of 1.00 D. Main outcome measures were refractive error and corrected-distance visual acuity (CDVA) and uncorrected-distance visual acuity (UDVA) values. Eyes were evaluated at 4mo post-su…
Contrast sensitivity after refractive lens exchange with diffractive multifocal intraocular lens implantation in hyperopic eyes
2008
Contrast Test chart at distance and near under 3 luminance levels (85.0 cd/m 2 , 5.0 cd/m 2 , and 2.5 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR IOL implantation in 30 hyperopic eyes with presbyopia and low astigmatism (%1.0 diopter). Results after surgery were compared with those before surgery. RESULTS: Six months postoperatively, the mean residual spherical equivalent refractive error was 0.21 diopter G 0.19 (SD). The best corrected distance and near visual acuities were comparable to those before surgery. For distance vision, the safety index was 1.02 and the efficacy index was 0.91. For near vision, the values were 1.04 and 1.02, respectively. There were no statistical…
Outcome of Bleb Revision With Autologous Conjunctival Graft Alone or Combined With Donor Scleral Graft for Late-onset Bleb Leakage With Hypotony Afte…
2020
Prcis Treatment of leakage with ocular hypotony after trabeculectomy with mitomycin C (MMC) can be safely achieved through conjunctival patch alone or combined with donor scleral graft in cases of melted underlying sclera. Purpose To report outcomes of 2 surgical approaches for treating ocular hypotony in eyes with blebs with late-onset leakage after standard trabeculectomy with MMC. Methods Thirty consecutive cases with bleb leakage and hypotony underwent bleb revision surgery between 2009 and 2014 by the same surgeon (J.W.) at the Department of Ophthalmology of the Mainz University Medical Center, Germany. In 18 patients, an autologous conjunctival patch graft was applied. In 12 patients,…