SEARCH · PubMed Health

Results for “Extended”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources

PubMed1993

The extended family and support for people with AIDS in a rural population in south west Uganda: a safety net with holes?

It is commonly assumed that the extended family in Africa provides a safety net for individuals in times of need. This paper examines this assumption using data on the care of people with AIDS in a rural population in South West Uganda. Over a six month period data were collected by counsellors on the care given to 30 (17 women, 13 men) AIDS patients by their families. In 27 of the 30 cases there was evidence of limited care. Various reasons were given for this by the carers, including lack of food and money for medications and the carer's other family responsibilities. For 17 clients who died during the study period, records of seven cases show that other relatives were asked to help with care but refused on the grounds of poverty or other commitments. However, in all but one of these cases extended families did provide assistance for the funeral. The findings suggest that there is a need to question the assumption that the extended family, in the culture under study, is able to provide adequate support for AIDS patients.

Acquired Immunodeficiency Syndrome↗

PubMed1988

Corneal endothelial polymegathism after the extended wear of rigid gas-permeable contact lenses.

To determine if there are any corneal endothelial cell size and shape changes in subjects wearing rigid gas-permeable contact lenses for cosmetic extended wear, six unadapted lens wearers were fitted using four different lens materials. Each subject wore one lens extended-wear and the other daily-wear for 3 months. Before lens wear and after 3 months, noncontact endothelial photographs were taken. Cell tracings were analyzed by a digitizing computer. This study showed significant endothelial polymegathism, an increase in maximum cell area to minimum cell area, and a significant decrease in percent frequency of hexagonal cells in the extended-wear eyes. There existed in these subjects a significant correlation between changes in cell size (polymegathism) and cell shape (pleomorphism).

Adult↗

PubMed2006

Pseudomonas aeruginosa-induced inflammation in the rat extended-wear contact lens model.

PURPOSE: To examine the early host response to Pseudomonas aeruginosa challenge in the extended contact lens-wearing rat model. METHODS: Lewis rats were fitted with extended-wear lotrafilcon A hydrogel lenses in the left eye, and the right eye served as the control. Bacterial challenge was initiated in the experimental eye by fitting a bacteria-soaked contact lens and by topical delivery of the bacteria. On first detection of corneal opacity, slitlamp examination, histopathologic examination, viable bacteria counts, enzyme-linked immunosorbent assay, myeloperoxidase, Langerhans cell detection, and multiprobe ribonuclease protection assays were used to evaluate the early corneal response. RESULTS: Analysis of bacterially challenged contact lens-wearing versus control rats showed Langerhans cells and polymorphonuclear neutrophils only in the experimentally challenged cornea. In addition, in the experimentally challenged cornea, ribonuclease protection and enzyme-linked immunosorbent analyses showed an upregulation of proinflammatory cytokines, including interleukins 1beta and 6, suggesting that with contact lens wear, these cytokines contribute to the early corneal response and, potentially, disease. CONCLUSIONS: The contact lens-wearing rat model allows a unique analysis of the early effects of bacterial challenge in extended-wear contact lenses in the absence of corneal scarring, used in most rodent models. The rat model should be valuable to delineate further the effects of contact lens wear, including the testing of additional contact lens-related complications.

Animals↗

PubMed2002

Confocal microscopic observations of stromal keratocytes during extended contact lens wear.

BACKGROUND: The aim of this study was to monitor changes in keratocyte density during extended contact lens wear and to explore the possible role of hypoxia and oedema in any changes observed. METHODS: Twenty-three neophyte myopic subjects wore a high Dk/t lens (PureVision) in one eye and a low Dk/t lens (Acuvue 2) in the other eye on an extended wear basis for six months. Slit-scanning confocal microscopy and ultrasonic pachometry were performed on both eyes at baseline (before lens wear), after three and six months of lens wear, and one week after cessation of lens wear (the 'post-cessation' visit). RESULTS: No differences were established between the two lenses or between the three study visits for anterior stromal keratocyte density (KD). Posterior stromal KD was similar for the two lenses throughout the study. However, there was an overall drop in posterior KD of 14 per cent in both eyes at the six-month visit, compared to the initial visit. Posterior KD at the six-month visit was no different from that at the post-cessation visit. Corneal thickness was similar for the two lenses at the initial and post-cessation visits, but was three per cent greater for the eye wearing the Acuvue 2 lens at the six-month visit. CONCLUSION: Extended contact lens wear causes a loss of keratocytes; this loss cannot be attributed to contact lens-induced hypoxia and/or oedema, or to an artifact of confocal microscopy relating to presence of residual oedema. It is postulated that lens-induced keratocyte loss may be related to the physical presence of contact lenses creating some mechanical effect.

Adult↗

PubMed2002

The ocular response to extended wear of a high Dk silicone hydrogel contact lens.

PURPOSE: A four-month extended wear clinical trial was conducted to compare the ocular effects of a high Dk Balafilcon A silicone hydrogel lens and a low Dk HEMA 38.6 per cent H20 soft lens. METHOD: Twenty-four subjects who were adapted to daily wear of soft lenses wore a high Dk lens in one eye and a low Dk HEMA lens in the other eye for four months on an extended wear basis after one week of daily wear. Thirteen progress evaluations were conducted using standard clinical procedures. RESULTS: Eighteen subjects (75 per cent) completed the study. The high Dk lens induced significantly less bulbar and limbal injection and corneal vascularisation than the low Dk HEMA lens (p < 0.05). Epithelial microcysts were observed only in the eyes wearing the low Dk lens. A significant increase in myopia was found in the eyes wearing the low Dk HEMA lens (mean = 0.50 D, p < 0.01) compared to the insignificant myopic increase of 0.06 D in the eyes wearing the high Dk lens. Three subjects developed small infiltrates in the high Dk lens wearing eyes and significantly more post-lens debris was observed under the high Dk lens. Six subjects developed papillary conjunctivitis in the eye wearing silicone hydrogel lenses but only two of those were discontinued from the study. CONCLUSION: No hypoxia-related effects were observed with extended wear of the high Dk Balafilcon A silicone hydrogel lens.

Adult↗

PubMed2001

Practical experience with a high Dk lotrafilcon A fluorosilicone hydrogel extended wear contact lens in Spain.

PURPOSE: Several research studies on high Dk soft contact lens materials have been published, but little has been reported from practical clinical experience with these new materials. This study reports in-practice clinical experience with the lotrafilcon A fluorosilicone hydrogel material from a 6-month study in Spain. METHODS: Eighty-five patients were dispensed lotrafilcon A lenses (Focuse NIGHT & DAY [CIBA Vision Corporation]) for monthly replacement by 13 investigators from eight practices. The recommended wear schedule was daily wear for the first week and then up to 6-night extended wear through the first month and up to 30-night extended wear through 6 months. Follow-up visits were at 1 week, 1 month, 3 months, and 6 months. Clinical and patient subjective data were collected at each visit. RESULTS: Among patients who continued in the study at each visit, Snellen visual acuity (VA) of 20/25 or better was achieved by at least 96% of all eyes at all visits; lens surfaces assessments for front surface deposits, front surface wetting, and back surface debris averaged less than grade 1 (0-4 scale) for all lenses at all visits; biomicroscopy grades averaged well below grade 1 (0-4 scale) for all eyes at all visits; acceptable or optimal fit was assessed for 97% or more of all lenses at all visits. These patients rated the average overall comfort, vision, and handling above 9 (0-10 scale) at 6 months and 98% reported satisfaction with the lenses at 6 months. Eighty-two percent of patients dispensed completed the study. Seven patients were discontinued because of fit, and seven were discontinued because of positive biomicroscopy signs. CONCLUSIONS: The lotrafilcon A lens performed well clinically and it was accepted well by patients, with most practitioners recommending and most patients wearing it for up to 30 nights extended wear. Practitioners should be attentive to fit and discomfort complaints at dispensing and follow-up and may want to recommend lubricating or rewetting drops for those patients with dryness symptoms.

Adolescent↗

PubMed2002

Development of a new extended-wear contact lens model in the rat.

PURPOSE: To develop a rat model to experimentally monitor the potential inflammatory effects of soft contact lens (CL) usage on the cornea during extended wear (EW). METHODS: Lewis rats were fitted with EW lotrafilcon A (CIBA Vision, Duluth, GA) hydrogel lenses (Dk/t 175 barrers/cm) in the left eye, the right eye serving as a control. After 12 days (n = 5 rats) and 30 days (n = 8 rats) of continuous extended wear, corneas were removed and total RNA was extracted from both CL-wearing and non-lens-wearing eyes. Multiprobe ribonuclease protection assays (RPA) were used to detect and compare cytokine and chemokine gene expression in corneas from both groups. RESULTS: Cytokine-chemokine mRNA expression levels were similar for interleukin (IL)-1alpha, IL-1 receptor antagonist (RA), IL- 18, transforming growth factor (TGF)-beta1, TGF-beta2, TGF-beta3, and macrophage migration inhibitory factor (MIF) levels in CL-wearing and non-lens-wearing corneas after 12 or 30 days of EW. CONCLUSION: This in vivo rat model for extended contact lens wear allows analysis and comparison of mRNA levels of cytokines and chemokines in the cornea with and without EW soft CL use. Remarkably, after 12 or 30 days of continuous CL wear, there was no significant up-regulation in lens wearing corneas for any of the cytokines-chemokines tested.

Animals↗

PubMed2002

Association of Pseudomonas aeruginosa and Serratia marcescens with extended-wear soft contact lenses in asymptomatic patients.

PURPOSE: To isolate and identify aerobic bacteria, particularly gram-negative species associated with the use of extended-wear (EW) soft contact lenses. METHODS: Extended-wear contact lenses were collected, using aseptic technique, from the eyes of individuals after 30 days of extended wear (5-7 day intermittent periods) and were examined for adhered aerobic bacteria. RESULT: Coagulase-negative staphylococci (CoNS) were isolated from 74% of the lenses. Serratia marcescens was found at an incidence of 10% and Pseudomonas aeruginosa at an incidence of 6%. CONCLUSION: The presence of species of bacteria, including P. aeruginosa and S. marcescens, that have been associated with daily wear soft contact lenses, solutions, and cases also appear to be associated with EW lenses.

Colony Count, Microbial↗

PubMed1992

A retrospective study of disposable extended wear lenses in 100 patients: year 2.

We present the results of the second year of follow-up of 100 patients wearing disposable contact lenses on an extended wear basis. Thirty-seven males and 63 females participated in the study (mean age: 41.1 years +/- 13.88 (mean +/- 1 standard deviation); and the mean patient follow-up time was 26 months +/- 4.9). A total of 13 patients were lost to follow-up. Seventeen patients discontinued extended wear yet continued to wear soft lenses on a daily wear basis--the reasons for this finding are discussed. A significant decrease in the number of events defined as complications (32 events) was noted when compared to the first year of follow-up (136 events). Seven corneal infiltrates occurred during the second year, compared to 6 such events during the first year of the study. Additional complications included: giant papillary conjunctivitis (6 cases), corneal staining (5 cases), and corneal abrasions (4 cases). Disposable extended wear soft contact lenses offer a reasonable means of vision correction in the properly selected patient. At the same time, caution should be exercised in the fitting and wear of these lenses.

Adolescent↗

PubMed1992

Extended contact lens wear enhances Pseudomonas aeruginosa adherence to human corneal epithelium.

Extended wear of soft contact lenses is associated with an increased risk of Pseudomonas aeruginosa infection of the cornea. To assess the role of bacterial adherence in the pathogenesis of these infections, superficial corneal epithelial cells and leukocytes from ten patients who use extended-wear soft lenses and ten control eyes were compared for their propensity to attach P. aeruginosa in vitro. Cells were washed from the cornea by saline irrigation, incubated with a 10-ml solution containing 10(7) colony-forming units/ml of bacteria at 35 degrees C for 30 min, collected on a filter, and prepared using a modified acridine orange staining method. Fluorescence microscopy showed bacterial adherence to corneal epithelial cells, leukocytes, and ocular mucus. The mean number of bacteria adhering to epithelial cells was 2.6 for control eyes and 6.6 for the lens-wearing eyes (P = 0.002). The percentage of epithelial cells attaching greater than or equal to four bacteria was higher for lens-wearing eyes than control eyes (57.4% versus 26.0%, P = 0.0005). There was no significant difference between contact lens-wearing eyes and control eyes in the number of leukocytes collected or in the number of bacteria attached to these cells. These results show that P. aeruginosa adherence to epithelial cells is enhanced in those who use extended-wear soft contact lenses, and this may contribute to the increased incidence of P. aeruginosa keratitis for this population.

Acridine Orange↗

PubMed1992

Rigid gas-permeable extended wear: a comparative clinical study.

A 12-month clinical trial involving 88 subjects was undertaken to compare the clinical performance of rigid gas-permeable contact lens extended wear (EWRGP) with that of RGP daily wear (DWRGP) lenses and soft lens extended wear (SLEW) with medium water content lenses. Withdrawals from the EWRGP group tended to result from lens-related problems, whereas the SLEW withdrawals generally resulted from adverse effects on corneal physiology. Changes in spherical refractive error during the 1-year study were small (less than 1.00 D) and similar for both gas-permeable lens-wearing groups. Most of the SLEW group (58%) showed an increase in myopia and the mean increase was 0.38 D, which represented a significant difference from the EWRGP group. The EWRGP group showed a mean flattening in corneal curvature of 0.11 and 0.15 mm in the flattest and steepest corneal meridians, respectively. A positive correlation was noted between change in corneal curvature and baseline corneal astigmatism, which suggests corneal molding as a result of lid pressure as the most likely cause. The DWRGP and SLEW groups showed small, nonsignificant changes in corneal curvature. Most of the EWRGP subjects (69%) who completed the study showed increased corneal distortion. This compares with 30 and 17% with the DWRGP and SLEW groups, respectively. Likely corneal edema was a major contributory factor. For most of the slitlamp variables monitored, there were no significant differences between the groups. However, microcystic changes were detected in both EWRGP (35%) and SLEW subjects but not in the DWRGP group. Corneal staining was noted in all groups but was more prevalent among the EWRGP group. The findings of this study are discussed in relation to the clinical management of RGP extended wear.

Adolescent↗

PubMed1991

Protein accumulation on disposable extended wear lenses.

We investigated protein accumulation on disposable extended wear contact lenses. Fifteen volunteers were fit with one low water content, non-ionic lens (Bausch & Lomb's SeeQuence) randomly assigned to one eye and a high water content ionic lens (Vistakon's Acuvue) assigned to the fellow eye. During the first 7 weeks of extended wear the lenses were removed weekly for sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of protein deposition, and replacement lenses were inserted. Four subjects completed additional test sessions of 1 minute, 15 minutes, 24 hours, and 1 week extended wear. Lysozyme accumulation, as measured by SDS-PAGE, increased with wearing times up to one week on all Acuvue lenses, but after 24 hours wear lysozyme accumulation did not increase on the SeeQuence lens. Proteins falling into the reported molecular weight ranges of albumin, PMFA, IgG, IgA (sec), lactoferrin and subunits of protein G were evident on all gels at 1 minute of wear, but these protein groups did not have a detectable increase in deposition after 24 hours wear for either the SeeQuence or the Acuvue lenses. In most cases, the protein accumulation evident from SDS-PAGE analysis was not observable by biomicroscopy using standard clinical methods. A few patients reported preference for the initial comfort and vision achieved by the Acuvue lens, but no preference was found after adaptation.

Adult↗

PubMedDate not supplied

Corneal requirements for extended wear: an update.

The current status of extended wear is reviewed in terms of the ability of available rigid and soft contact lens materials to provide: oxygen to the cornea, lens movement, and resistance to deposit formation and corneal desiccation. Current hydrogel lenses seem unsuitable as a modality for extended wear due to limited oxygen transmissibility, except when the frequency of overnight wear is reduced. Rigid gas permeable lenses, while not without problems, show greater promise for extended wear at this time.

Contact Lenses, Extended-Wear↗

PubMed1987

Evaluation of endothelial integrity in extended wear.

The purpose of this investigation was two-fold: 1) to evaluate and compare the endothelium of hydrogel and rigid extended wear contact lens patients and 2) to evaluate a new technique for in-office endothelial photography. Endothelial photography was performed on seven patients who had worn low water content ultrathin soft lenses and seven patients who had worn rigid extended wear lenses for 1 year. In addition, seven non-lens wearers were used as a control group. Endothelial polymegathism and pleomorphic changes were evaluated via photographic observation using a new endothelial photography technique developed by G. Michael Murphy, O.D. The results showed that this was a viable method of endothelial photography for monitoring extended wear contact lens patients.

Conjunctival Diseases↗

PubMed1987

Bilateral simultaneous Pseudomonas keratitis with myopic extended-wear contact lenses.

Bacterial keratitis is reported more frequently in the literature with the use of extended-wear contact lenses. This report describes a case of bilateral simultaneous pseudomonas keratitis in an elderly patient wearing extended-wear contact lenses for correction of myopia. The lenses were not properly disinfected prior to the development of the corneal ulcers. When bacterial keratitis is suspected with the use of extended-wear contact lenses, prompt diagnosis and treatment are necessary. Appropriate microbiologic testing of the contact lenses, lens cases, and lens solutions should also be undertaken.

Aged↗

PubMed1985

Effects of long-term extended contact lens wear on the human cornea.

The effects of long-term extended wear of soft contact lenses on the human cornea were determined by examining 27 patients who had worn a high water content hydrogel contact lens in 1 eye only for an average of 62 +/- 29 months (mean +/- SD). The other eye, which was either emmetropic or amblyopic, acted as a control. The lens-wearing eye showed a 14.8% reduction in epithelial oxygen uptake (P less than 0.001), a 5.6% reduction in epithelial thickness (P less than 0.05), a 2.3% reduction in stromal thickness (P less than 0.05), the induction of epithelial microcysts, and a 22.0% increase in endothelial polymegathism (P less than 0.001). Endothelial cell density was unaffected by extended lens wear. No interocular differences in any of these physiological characteristics were found in a matched control group of anisometropic and amblyopic subjects who did not wear contact lenses. The patients ceased lens wear for up to one month and recovery of corneal function was monitored during this period. Epithelial oxygen uptake and thickness recovered within 33 days of lens removal. The number of microcysts increased over the first 7 days, but decreased thereafter; some microcysts were still present 33 days after lens removal. Recovery from stromal thinning had not occurred after 33 days following lens removal. There was a slight reduction in polymegathism in some patients, but overall this was not statistically significant. These findings establish (1) that the extended wear of hydrogel lenses induces significant changes in all layers of the cornea; (2) that lens wear suppresses aerobic epithelial metabolism, which may compromise the epithelial barrier to infection; and (3) that changes to the stroma and endothelium are long-lasting. Lens-induced effects on corneal physiology can be minimized by fitting lenses that have greater oxygen transmissibility (are thinner), are more mobile, more frequently removed, and more regularly replaced.

Adolescent↗

PubMed1984

Experience with the Sauflon 70 (Lidofilcon A) soft contact lenses for extended wear in myopia.

Sixty-four myopic patients were studied who wear the Sauflon 70 (Lidofilcon A) lens on an extended wear basis. The study showed that this lens is safe and effective for extended wear. It is a durable lens and can be sterilized by heat as well as chemical means, but seems to develop calcium deposits at the same ratio as other extended-wear lenses used for the correction of myopia.

Adolescent↗

PubMed1984

Critical oxygen levels to avoid corneal edema for daily and extended wear contact lenses.

The relationship between corneal edema and hydrogel lens oxygen transmissibility was examined for both daily and extended contact lens wear by measuring the corneal swelling response induced by a variety of contact lenses over a 36-hr wearing period. The relationships derived enable average edema levels that occur with daily and extended wear in a population of normal young adults to be predicted to within +/- 1.0%. The critical lens oxygen transmissibilities required to avoid edema, for the group as a whole, for daily and extended contact lens wear were obtained from the derived curves. It was found under daily wear conditions that lenses having an oxygen transmissibility of at least 24.1 +/- 2.7 X 10(-9) (cm X ml O2)/(sec X ml X mmHg), an Equivalent Oxygen Percentage (EOP) of 9.9%, did not induce corneal edema. This level of oxygen transmissibility can be achieved (1) in standard, low water content, poly-HEMA lenses by using an average lens thickness of 33 microns or less, or (2) in a higher water content material, such as Duragel 75, by using an average thickness of 166 microns or less. The critical hydrogel lens oxygen transmissibility needed to limit overnight corneal edema to 4% (the level experienced without a contact lens in place) was found to be 87.0 +/- 3.3 X 10(-9) (cm X ml O2)/(sec X ml X mmHg)--an EOP of 17.9%. This ideal level of oxygen transmissibility cannot, at present, be provided with hydrogel materials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗