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

In a controlled clinical pilot study 48 aphakic eyes were fitted with HEMA soft lenses on the 3rd postoperative day. An optically satisfactory and wearable fit was obtained neither with the conventional hydrated Weicon 38, nor with the highly hydrophilic Weicon 72. The main reasons were centralizing and motility defects of the lenses, which might be eliminated by an improved lens design. A further 57 patients showed an increase in corneal thickness following cataract extraction. The early fitting of permanent soft aphakic lenses should be delayed until the 4th day postoperatively, by which time the oedema has reduced and the cornea has reached approximately its pre-operative thickness.
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PMID:[Postoperative fitting of soft contact lenses in aphakia. (A trial with Weicon 38 and Weicon 72) (author's transl)]. 62 75

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

An in vitro model to assess lens epithelial cell adhesion to a variety of intraocular lens materials was developed. Rabbit anterior lens capsules were isolated and cultured in serum-containing medium. Test surfaces included poly(methyl methacrylate), two new silicones (SLM-1/UV, SLM-2/UV), two hydrogels (HEMA, Lidofilcon A), and polytetrafluoroethylene (PTFE). Following the application and culturing of cells on the test surfaces, adherent cells were removed by trypsinization and counted at eight and 24 hours. The material surfaces were characterized by electron spectroscopy for chemical analysis and scanning electron microscopy. The captive bubble technique was also used to assess interfacial free energy. More cells adhered to PMMA than to the other materials tested (P less than .01). The two silicones, HEMA, and PTFE did not differ significantly from each other; Lidofilcon A had the lowest cell adhesion of all materials tested. Cell adhesion results were related to the interfacial free energy of each material. Materials of low (less than 5 ergs/cm2) or high (greater than 40 ergs/cm2) interfacial free energies had lower cell adhesion than materials of intermediate free energies (5 to 40 ergs/cm2) which exhibited the highest cell adhesion.
J Cataract Refract Surg 1991 Nov
PMID:Surface properties of intraocular lens materials and their influence on in vitro cell adhesion. 177 48

Over a two-year postoperative period, cells on hydrogel (poly HEMA) and poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) were observed by specular microscopy. First small, round cells and fibroblast-like cells and later epithelioid-like cells and foreign-body giant cells could be seen on both IOL types. In eyes with prolonged postoperative inflammation a greater number of cells was observed and the cells remained on the IOL surface for a longer period. We found fewer cell reactions on hydrogel IOLs during the postoperative period of our follow-up. Foreign-body giant cells were observed on only 9%. These cells were smaller than those on PMMA IOLs. This finding may suggest that poly HEMA demonstrates greater biocompatibility, with regard to this foreign-body cell reaction, than PMMA. However, we found more pigment dispersion (50%) on the surface of hydrogel IOLs. These pigment deposits induced no cell reactions and there was less phagocytosis of the pigment debris. In 7% of the cases, dust-like, white precipitates of uncertain origin were seen; in 5% amorphous debris was seen. Fine scratches caused by polishing during the manufacturing process were seen in some cases. The postoperative clinical signs for PMMA and hydrogel IOLs were similar.
J Cataract Refract Surg 1991 Nov
PMID:Cellular invasion on hydrogel and poly(methyl methacrylate) implants. An in vivo study. 159 42

The implantation of foldable intraocular lenses (IOL) takes advantages of the benefit of small incision cataract surgery provided by phacoemulsification. However, even experienced surgeons may find the new implantation techniques required initially difficult. Advantages of small incision techniques include maintaining stability of the globe during surgery, especially in the case of acute IOP elevation caused by choroidal effusion or expulsive hemorrhage, as well as improved postoperative healing. Small incision surgery minimizes induced astigmatism, to less than 1.0 dpt change. Therefore, the patients physical and visual rehabilitation can be accelerated. Soft IOL's composed of p-HEMA or Silicone materials have been investigated for the past ten years and appear to be well biocompatible. The p-HEMA lens most often implanted is the IO-GEL, manufactured by Alcon. 120 p-HEMA IOL's were implanted in our clinic over the past 2 years. Our experiences with this foldable IOL are reported.
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PMID:[Implantation of folding posterior chamber lenses]. 205 35

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

This study presents our experience with 34 HEMA disc intraocular lenses implanted in the capsular bag. Despite the small number of cases and the relatively short mean postoperative follow-up of nine months, the results show a low incidence of uveitis and capsular fibrosis and excellent biocompatibility. The following complications were observed: four luxations of the 8 mm lens and one of the 9 mm lens in the anterior chamber. A visual acuity of 20/20 to 20/40 was obtained in 32 patients (94%).
J Cataract Refract Surg 1990 Sep
PMID:Early results with the 8 mm and 9 mm HEMA disc intraocular lens. 223 72

A single piece hydrogel IOGEL (poly-HEMA) intraocular lens was implanted in 76 eyes. Patients obtained a visual acuity of 20/40 or better in 86.9% of cases and a best case visual acuity of 20/40 or better in 98.5% of cases. Patients were followed an average of 12 months (four to 19 months). Two lenses were exchanged with poly(methyl methacrylate) lenses because of decentration-induced glare. Cystoid macular edema occurred in two cases, resulting in visual acuity worse than 20/40 in one case. Results of the study at one year mean follow-up indicate the safety and efficacy of the IOGEL lens as an intraocular implant.
J Cataract Refract Surg 1990 Jan
PMID:Seventy-six consecutive cases of IOGEL intraocular lens implants. 229 74

The relations between the deformation and resulting resilience of lens haptics with various geometries and made of different materials were studied. While there are no fundamental differences between PMMA and PP haptics with identical geometries, the resilience of soft lenses made of poly-HEMA and silicone rubber subjected to the same deformation is significantly higher. On the basis of such measurements it is possible to estimate stress on the capsular bag during and after implantation. In light of recent publications concerning the prevention of secondary cataract, permanent circular tensioning of the lens capsule appears a desirable goal. This requirement is best satisfied with a material with permanently high elasticity, which tensions the equator of the capsular bag over 360 degrees.
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PMID:[Flexibility of intraocular lens haptics of various geometry and materials]. 239 99

Implantation of a hydrogel (IOGEL) intraocular lens in humans has been reported. The polyhydroxyethyl methacrylate (poly HEMA) matrix of this hydrogel is permeable to water soluble drugs and may adsorb agents used intracamerally during cataract extraction or topically during the postoperative period. This study compared the in vitro uptake and release of chloramphenicol, dexamethasone, epinephrine, pilocarpine, and bovine serum albumin by polymethylmethacrylate and hydrogel intraocular lenses with that of the intact crystalline lens of humans and rabbits. An in vivo study compared the uptake and release of chloramphenicol and dexamethasone by hydrogel lenses implanted in the anterior chamber of rabbit eyes with that of the rabbit's crystalline lens. The in vitro uptake and washout of epinephrine and pilocarpine by the hydrogel lens was comparable to the human lens. Uptake of chloramphenicol and dexamethasone by the hydrogel lens exceeded that of the human lens and, following a two-hour washout period, the dexamethasone content of the hydrogel lens remained significantly greater than the human lens. The uptake and washout of bovine serum albumin by the hydrogel lens was half that of the human lens. In vivo, the hydrogel lens efficiently eluted both chloramphenicol and dexamethasone. These studies show that a hydrogel lens will not act as a significant depot for drugs in the eye.
J Cataract Refract Surg 1989 Mar
PMID:Drug uptake and release by a hydrogel intraocular lens and the human crystalline lens. 272 18


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