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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intraocular lenses were implanted in 16 eyes of 13 patients with congenital cataract, and visual progress was plotted using a preferential-looking technique. Initial surgery was by lens aspiration with preservation of the posterior capsule, and subsequent posterior capsulotomy without anterior vitrectomy. Poly-HEMA posterior chamber lenses were used, usually as a primary procedure but in four cases as a secondary procedure after contact lens failure. No serious complications were encountered. Most eyes achieved a very significant visual improvement, and none were worse than preoperatively. Residual refractive error was highly unpredictable, but did not exceed 6 dioptres. The importance of rigorous occlusion therapy is stressed. With close follow-up, this procedure offers an effective and safe method for the correction of unilateral paediatric aphakia, and, in selected cases only, for bilateral aphakia.
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PMID:Results of intraocular lens implantation in paediatric aphakia. 128 13

Poly(methyl methacrylate) (PMMA) based intraocular lenses (IOLs) such as injection-molded PMMA and lathe-cut PMMA IOLs and soft IOLs such as silicone and poly(hydroxyethyl methacrylate)(polyHEMA) IOLs were tested for vulnerability to Nd:YAG laser photodisruption. The laser beam was focused on the posterior surface and inside of the IOLs in balanced salt solution. Cracks and central defects with radiating fractures were observed in PMMA IOLs; blistered lesions and localized pits were observed in silicone and polyHEMA IOLs, respectively. A molten edge surrounding the large hole, which was an indication of the thermal effect of the laser, was observed in the injection-molded PMMA while only a minute lesion was found in the polyHEMA IOL which contained 38% water. The size of the superficial damage of the IOL increased as the power of laser irradiation increased and PMMA IOLs showed greater damage than soft IOLs (P < .05).
J Cataract Refract Surg 1992 Nov
PMID:Effect of neodymium:YAG laser photodisruption on intraocular lenses in vitro. 143 66

Injection molded poly(methyl methacrylate) (IM-PMMA), lathe-cut PMMA (LC-PMMA), heparin surface modified PMMA (HSM-PMMA), silicone, and polyhydroxyethyl methacrylate (polyHEMA) intraocular lenses (IOLs) were incubated with platelets, granulocytes, mouse macrophage-like RAW 264.7 cells and mouse fibrosarcoma L929 cells to examine their compatibility. The number of cells attached to the IOL was counted after the central IOL area (0.04 mm2) was photographed with an inverted light microscope. Cell morphology was examined by scanning electron microscopy (SEM). More platelets and granulocytes were attached to the IM-PMMA and silicone IOLs than to the HSM-PMMA and polyHEMA IOLs (P less than .05). RAW 264.7 and L929 cells grew on PMMA-based and silicone IOLs, whereas HSM-PMMA and polyHEMA IOLs did not support an abundant growth of these cells. Granulocytes were incubated with the IOLs in the presence of Luminol and the generation of chemiluminescence was measured. Poly(methyl methacrylate)-based IOLs caused granulocytes to release significant amounts of oxygen radicals, while the polyHEMA IOL was almost inactive in stimulating granulocytes. Silicone and HSM-PMMA IOLs showed an intermediate level of stimulating activity. The light intensity reached a peak within 14 minutes with the IM-PMMA IOL, and in about 18 minutes with the other IOLs. Our results suggest that IOL hydrophilicity prevents attachment of cells and that a hydrophilic, soft surface can discourage granulocyte stimulation.
J Cataract Refract Surg 1992 May
PMID:Compatibility of intraocular lenses with blood and connective tissue cells measured by cellular deposition and inflammatory response in vitro. 159 30

Perioperative iatrogenic lesions due to physico chemical trauma may worsen a primary endotheliopathy or lead to a secondary endotheliopathy with subsequent decompensation and corneal opacification. The incisions in anterior segment surgery induce permanent vertical cellular disparity, considering the peripheral endothelium in an area that may correspond to its germinative zone. Cells are lost by corneal folding, e.g., during nuclear expression or sutureinduced distortion. Floating nuclear particles and a high perfusion volume, e.g., during phacoemulsification or vitrectomy in aphakic eyes, create diffuse cellular necrosis. The same thing happens with chemically or osmotically inadequate perfusion media or extraocular solutions applied to the open eye during surgical interventions, e.g., to maintain mydriasis. Large areas of cell erosion are encountered after direct contact with instruments and PMMA. This has been one of the reasons for the development of new IOL materials like Poly-Hema or silicone that are less traumatizing for the endothelium. Long-lasting endothelial lesions result from direct contact with IOL haptics or mobile iris- or angle-supported lenses. The effect of a short post-operative rise in IOP on the endothelium is not clear. For all lens styles and materials, it still remains unclear whether there is chronic subclinical inflammation due to the IOL plastic material itself or not. To protect the endothelium, e.g., during cataract surgery, several techniques have been developed: preoperative hypotony; nuclear expression respecting corneal topography; the use of small amounts of mostly physiological rinsing solutions warmed to body temperature; endocapsular irrigation-aspiration; posterior chamber phacoemulsification; posterior chamber IOL implantation with an anterior chamber deepened by air and/or viscoelastics; postoperative reduction of the IOP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Endothelial protection in surgical interventions and corneal donor tissue]. 208 3

The relationship between experimentally induced intraocular lens (IOL) haptic deformation and resulting elastic haptic counter-resisting forces measured by electronic dynamometry was examined for 34 different IOL haptics of varying material composition and geometrical designs. Poly(methyl methacrylate) (PMMA) and polypropylene loops of similar geometry did not fundamentally differ from one another, although lenses of differing geometry behaved differently. Unlike PMMA and polypropylene loops, soft haptics of poly-HEMA and silicone rubber demonstrated a larger elastic resistance force to the same degree of deformation. This was based upon design characteristics of the lenses and not upon intrinsic properties of the materials, which would have produced the opposite result. By comparative analysis of these dynamometer measurements and considerations of the lens design and elastic properties (including memory) of the component materials, we can calculate the stresses upon the zonular and capsular bag structures during and after IOL implantation.
J Cataract Refract Surg 1990 Sep
PMID:Measurement of elastic resisting forces of intraocular haptic loops of varying geometrical designs and material composition. 223 68

Various complications following intraocular lens (IOL) surgery result in explantation of the lenses. Haptic fibrosis may necessitate cutting the IOL haptics prior to removal. In this study we used the neodymium: YAG (Nd:YAG) laser to cut polypropylene and poly(methyl methacrylate) (PMMA) haptics in vitro and in rabbit eyes. In vitro we were able to cut 100% of both haptic types successfully (28 PMMA and 30 polypropylene haptics). In rabbit eyes we were able to cut 50% of the PMMA haptics and 43% of the polypropylene haptics. Poly(methyl methacrylate) haptics were easier to cut in vitro and in vivo than polypropylene haptics, requiring fewer shots for transection. Complications of Nd:YAG laser use frequently interfered with haptic transections in rabbit eyes. Haptic transection may be more easily accomplished in human eyes.
J Cataract Refract Surg 1989 Sep
PMID:Neodymium:YAG laser cutting of intraocular lens haptics in vitro and in vivo. 281 89

The green ocular lens autofluorescence was determined in 30 Poly Methyl Meth Acrylate (PMMA) contact lens wearing volunteers and compared to that of 21 healthy non-contact lens wearing controls to determine whether a contact lens, reducing UV-A intensity reaching the eye, might protect the ocular lens against cataract formation. Increased autofluorescence was considered an indicator of increased probability for cataract formation. A multiple regression procedure revealed a significant yearly increase of autofluorescence with age (p < 0.01) which did not differ significantly (p > 0.86) from that in the controls. The regression procedure also revealed a decrease of the autofluorescence as a function of contact lens wear, but this decrease was not significant (p = 0.3). The order of magnitude of the decrease (-25%) corresponded to that of the calculated decrease in UV-A intensity at the ocular lens (-39%). This study could not support the thesis that cataract formation can be prevented by wearing PMMA contact lenses.
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PMID:The blue-green autofluorescence of the human ocular lens after the wear of PMMA contact lenses. 801

Poly(methyl methacrylate)-based terpolymers bearing sulfonate and carboxylate groups have been synthesized by radical copolymerization leading to polymers with random distributions of ionic monomer units. Fibroblast cells were seeded on terpolymers of various molar compositions of ionic groups. Kinetics of the cell proliferation were examined and systematically compared to the nonfunctionalized control polymer, poly(methyl methacrylate). Modulation of cell proliferation was observed on 15% ionic monomer content copolymers of various compositions (R = COO(-)/(COO(-) + SO(3)(-)) and varies from 0 to 1). The inhibition percentage of cell proliferation calculated for each polymer by comparison to the cell proliferation on the control was plotted against R and gave a maximum value for R close to 0.55. Copolymers with ionic group contents higher or lower than 15% exhibit inhibition percentages fitting with those previously observed for the same R values, showing that the hydrophilic properties are not sufficient to explain the modulation effect of this material toward cells. Moreover, for each polymer tested, cells, even if inhibited in growth, were shown to be viable, indicating that the synthesized terpolymers exhibit cytostatic properties excluding any cytotoxic effect. Such polymers may be used for the fabrication of biocompatible intraocular lenses and prevent secondary cataract.
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PMID:Modulating fibroblast cell proliferation with functionalized poly(methyl methacrylate) based copolymers: chemical composition and monomer distribution effect. 1186 55

Poly(methyl methacrylate) refractive intracorneal ring segments (ICRS) can be removed for a refractive miscorrection or for early complications after implantation. We report the first case of a woman who experienced anterior stromal necrosis 5 years after an ICRS surgical procedure.
J Cataract Refract Surg 2003 Jun
PMID:Intrastromal corneal ring segments and corneal anterior stromal necrosis. 1284 96

The aim of the present work was to prepare microparticles containing vancomycin for intraocular injection. The primary objective was to guarantee continuous release and keep an intracameral drug concentration above the minimal inhibitory limit for at least 24h, needed in endophthalmitis prophylaxis after cataract surgery. Poly(lactide-co-glycolide) microparticles were prepared using the double emulsion (water-in-oil-in-water) solvent extraction/evaporation method. The influence of preparation parameters on the final microparticles properties was explored in an attempt to control particle sizes, stability, encapsulation rate and vancomycin release profile. Satisfying release profile and stability were obtained, independently of the process. Sizes and encapsulation rate were controlled using an experimental design. Final obtained properties demonstrated that the fabricated particles are suitable for the prophylactic intraocular use in cataract surgery. Further in vitro and in vivo experiments will be conducted to assess efficiency of the entrapped antibacterial and then validate its potential usefulness in prophylaxis.
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PMID:Preparation of vancomycin microparticles: importance of preparation parameters. 1687 47


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