Aphakia--selection of patients for contact lenses, intraocular lenses or spectacles. Review of 1,000 cataract operations.
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Adult↗
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Bacterial adhesion to intraocular lenses.
Intraocular lenses removed because of recurrent episodes of intraocular inflammation showed bacteria adhering to the prosthesis. Infections localized to areas around intraocular lenses have been reported in the literature. Two such infections and an in vitro study of bacterial adherence to implant surfaces are reported. Adherent bacteria were found to be more numerous on the polypropylene haptic than on the polymethylmethacrylate optic in both in vitro and in vivo cases. We suggest that the intraocular lens becomes contaminated with commensal organisms of low virulence during insertion into the eye, and that these organisms are the source of the inflammatory episodes. Experiments show that lenses as supplied are sterile and that in vitro bacteria adhere preferentially to the haptic.
Bacterial Adhesion↗
Sodium hydroxide sterilzation of intraocular lenses.
Intraocular lenses of polymethylmethacrylate contaminated with various inocula of bacteria, spores, and fungi were sterilized by modifications of the Ridley method using sodium hydroxide. Positive cultures were obtained from iris-supported lenses contaminated with concentrations of approximately 1 x 10(6) organisms per milliliter after one hour in 10% NaOH. No positive cultures were obtained when lenses remained in 10% NaOH for three hours, a time corresponding to a 1 x 10(-6) probability of surviving organism. The NaOH method, when appropriately used, is an effective sterilization process for intraocular lenses.
Aspergillus niger↗
Interim FDA report on intraocular lenses.
Intraocular lenses have been regulated by the Food and Drug Administration since February 9, 1978. Data reported through August 9, 1979 reveal 177,503 lenses of four different classes have been implanted. The anterior chamber intraocular lens appears to have a higher incidence of certain postoperative complications compared with both control operations and implantation of lenses in the other three classes. The anterior chamber intraocular lens appears to be associated with a lower level of visual acuity compared with both control cases and the other three lens classes during the first six months following implantation. Some complications occurred less frequently following implantation of intraocular lenses than in control cases.
Humans↗
Corneal endothelial damage from previously implanted intraocular lenses.
Intraocular lenses which had been surgically removed from human eyes were compared to new uncoated IOLs with regard to damage caused by dynamic and static contact with fresh rabbit corneal endothelium. Previously implanted IOLs caused consistently less endothelial damage. Possible mechanisms and the implications of these findings for the corneal surgeon doing pseudophakic keratoplasty are discussed.
Aged↗
Neodymium:YAG laser damage of intraocular lenses.
Intraocular lenses (IOLs) suitable for implantation were analyzed for the presence of refractile particles. These were found in lathe-cut and injection-molded lenses from various manufacturers. A YAG laser was focused 2 mm beyond the IOLs in a special test chamber and fired through them. The IOLs were then analyzed for damage. A photographically documented study of six IOLs using Q-switched and mode-locked lasers showed optical breakdown occurring within the IOLs; this was not clearly related to refractile particles. Optical breakdown did not occur in two IOLs with a similar number of refractile particles. Damage was seen with the mode-locked but not with the Q-switched laser. The optical breakdown occurred more frequently at high power (5.0 mJ) than at low power (1.2 mJ).
Lasers↗
Comparison of complement activation by silicone intraocular lenses and polymethylmethacrylate intraocular lenses with polypropylene loops.
Silicone intraocular lenses are undergoing clinical investigation for use in the United States. We compared the ability of silicone intraocular lenses to activate the complement system in human sera with that of polymethylmethacrylate intraocular lenses with polypropylene loops using a radioimmunoassay that measures levels of activated complement fragments. Sera incubated with polymethylmethacrylate lenses with polypropylene loops had higher levels of C3a and C5a, but not C4a, than control sera incubated without intraocular lenses. On the other hand, there were no differences in levels of C3a, C4a, and C5a between sera incubated with silicone lenses and control sera. These results suggest that polymethylmethacrylate lenses with polypropylene loops activate the alternative pathway of complement, while silicone lenses do not.
Complement Activation↗
Update report on intraocular lenses.
Intraocular lenses have been regulated by the Bureau of Devices of the Food and Drug Administration since February 9, 1978. One year ago, data were reported through August 9, 1979, at which time more than 177,000 lenses of four different classes had been implanted. In the meantime, appeals and legal action by the Public Citizens Health Research Group of Washington, DC, have resulted in a re-examination of the intraocular lens issue and the FDA study of the lenses, which has resulted in a delay in any premarket approval, and prohibits the public release of the results of the study to date. This sequence of interesting interactions between physicians, manufacturers, the Food and Drug Administration, and a "consumer" group is outlined.
Consumer Organizations↗
A new matrix formulation of spectacle magnification using pupil magnification. II and III: High myopia corrected with contact lenses and intraocular lenses.
In this paper we use the matrix method to calculate spectacle magnification (SM) and relative spectacle magnification (RSM) using pupil magnification for myopic eyes corrected with contact lenses (CLs), and intraocular lenses (IOLs). For myopic eyes corrected with contact lenses, the calculation is very similar to the one done for myopic eyes corrected with ophthalmic lenses (OLs) since both OLs and CLs are external correcting systems. For myopic eyes corrected with intraocular lenses, the calculation is different from the ones carried out for myopic eyes with external correcting systems. In this paper we show the differences that exist between the matrix calculations for these two correcting systems, external and internal. The magnifications are calculated for specific myopic eyes corrected with CLs and IOLs. By comparing the results obtained with three correction types, namely, OLs, CLs and IOLs, we will be able to choose the best correction system for each case.
Contact Lenses↗
Ultraviolet-absorbing spectacle lenses, contact lenses, and intraocular lenses.
Optical materials that are available to the practitioner for protection of the eye against hazardous exposure to ultraviolet radiation (UVR) are discussed. Principles of protection, procedures for calculating safe ocular exposure duration, and transmittance curves of commonly prescribed spectacle lenses, contact lenses, and intraocular lenses are discussed. Suggestions are made to assist the practitioner in providing adequate protection for the patient.
Animals↗
Use of high-density vitreous substitutes in the removal of posteriorly dislocated lenses or intraocular lenses.
We successfully used high-density vitreous substitutes to remove four dislocated crystalline lenses and three dislocated intraocular lenses (IOLs) from the vitreous cavity. Fluorosilicone oil (300 cs) was used to remove the four lenses and one of the IOLs. Perfluorophenanthrene (Vitreon) was used to remove the other two dislocated IOLs. The dislocated lenses or IOLs were floated by the high-density vitreous substitutes and removed safely without damaging the retina; there were no intraoperative complications. Postoperative residual fluorosilicone oil droplets were found in one case.
Adult↗
The effect of heparin-coated intraocular lenses on intraocular pressure following combined trabeculectomy and cataract surgery.
PURPOSE: To review the effects on intraocular pressure control of the use of standard and heparin-coated intraocular lenses (IOLs) following combined cataract and glaucoma surgery after a minimum period of 2 years. METHODS: Case note review of all patients with glaucoma who required cataract extraction combined with trabeculectomy and who were randomized to either of the two IOL types. The number of ocular hypotensive medications and the intraocular pressures were recorded pre-operatively and at 3, 6, 18 and 24 months following surgery. RESULTS: The two groups (9 receiving standard IOLs and 10 heparin-coated IOLs) were comparable for age, sex and follow-up, as were the pre-operative intraocular pressures and number of treatments. Post-operatively, all patients achieved an intraocular pressure < 21 mmHg at the final visit, with only one patient in each group requiring topical medication, but the standard lens group had a higher intraocular pressure at 2 years (p<0.05). The magnitude of the fall from the pre-operative values was greater in the heparin-coated lens group at 2 years after surgery (p<0.02). The presence of a visible drainage bleb occurred equally frequently in the two groups. CONCLUSIONS: Use of a heparin-coated IOL does not adversely affect the intraocular pressure control following combined cataract and drainage surgery. The greater fall in intraocular pressure at 2 years in those receiving a heparin-coated IOL may have occurred by chance.
Aged↗
[Materials for intraocular lenses. II. Silicone intraocular lenses].
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Animals↗
Surgical management of dislocated intraocular lenses.
Intraocular lens (IOL) malpositions range from simple IOL decentration to luxation into the posterior segment. Many surgical techniques and approaches have been devised to treat visually significant IOL dislocation. In this series, 78 eyes with IOL dislocation were managed by anterior segment and vitreous surgeons with a variety of surgical techniques using a limbal, pars plana, or combined limbal-pars plana approach. Most of the dislocated lenses were posterior chamber IOLs. In 39 of 78 eyes (50%), final visual acuity was 20/50 or better. Neither surgical approach nor management technique appeared to be related to outcome. The timing of surgery did not appear to affect visual outcome but was not examined in a randomized fashion. Guidelines for determining optimal management are presented.
Adult↗
Extended-wear contact lenses and intraocular lenses for aphakic correction.
We evaluated extended-wear soft contact lens use in 128 aphakic eyes of 113 patients, 44 of whom had been unable to wear conventional contact lenses; 116 eyes (91%) have been successfully fitted and have worn the extended-wear lenses without significant complication. Eleven patients were unable to wear the lens or had to be discontinued for transient lens-related problems. In 103 eyes successfully fitted the lens is removed for cleaning less often than monthly. Ninety six of the 116 eyes fitted have visual acuity as good as, or better than, with aphakic correcting spectacles. The results obtained with the extended-wear soft contact lens are similar to those obtained with intraocular lenses, except for the recent high incidence of inflammation seen after intraocular lens insertion when using ethylene-oxide-sterilized lenses.
Adolescent↗
Preexisting primary glaucoma and intraocular lenses.
Intraocular lens implantation into cataractous eyes that also suffer from primary glaucoma is a rewarding procedure. The need for an IOL in these eyes is even stronger than in otherwise healthy cataractous eyes. With prepupillary IOLs there was a strong reason first to control surgically intraocular pressure prior to cataract surgery with IOL implantation. The advent of retropupillary IOLs has dramatically changed this attitude. Extracapsular cataract extraction (ECCE) and the use of an all-in-the-bag retropupillary IOL is the method of choice. Postoperative medical treatment remains possible as does surgical treatment for the glaucoma. The procedure is suitable for open-angle glaucoma as well as for narrow-angle glaucoma.
Cataract↗
A review of intraocular lenses.
Intraocular lens implants are being used in ever increasing numbers for the correction of aphakia. For that reason optometrists should familiarize themselves with the types of implants used and the advantages and disadvantages of each. This article will review the types of implants the optometrist is likely to see. The changing trends in implant surgery will be considered along with explanations for the changes. Several studies of patients with implants are reviewed. Finally, a format for evaluating implant patients is presented.
Cataract Extraction↗
Comparative analysis of human serum albumin adsorption and complement activation for intraocular lenses.
Intraocular liquid, in contrast to blood, has no cellular components; therefore, proteins (human serum albumin [HSA], and [alpha, beta, gamma] globulins) are the major components that determine patients' response to the intraocular lens (IOL) surface. In addition to the amount of adsorbed proteins, the possibility of its conformational changes, including conformational changes of globulins C1 and C3 that respond for the activation of the complements system by the classical and alternative pathways, cannot be excluded. The interaction between IOLs and protein components of intraocular liquid directly influences the ocular exudative reaction in the early postoperational period, the intensity of cellular and pigmental scurf on the surface of the IOLs, and the state of endothelial cells of the cornea in the distant postoperational period. Our goal was to compare the interaction of commercial IOLs made from polymethylmethacrylate, silicone, poly-2-hydroxyethyl methacrylate (p-HEMA), and copolymer p-HEMA with collagen with HSA and the complement system. The total internal reflection fluorescence (TIRF) method and hemolytic assay were used for this task, respectively. It has been demonstrated that the probability of biocompatibility of commercially produced IOLs on the stage of protein adsorption can be evaluated using the kinetic of HSA-fluorescein isothiocyanate adsorption onto the IOL surface by the TIRF METHOD: In the case of IOLs from p-HEMA, a negative correlation was shown between the degree of irreversible adsorption of HSA and the minimum relative rate constant of the surface-induced complement activation. We did not find any correlation between hydrophilicity/hydrophobicity of lenses and their adsorptional properties including complement activation. From suggested adsorptional criteria in vitro for biocompatible surfaces, the hydrogel lens from p-HEMA has a lower probability of biocompatibility in comparison with other IOLs.
Adsorption↗