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At least 271 records · Page 15Linked to original sources
PubMed2006

Cultured human ocular surface epithelium on therapeutic contact lenses.

BACKGROUND: This study was initiated after observation of some intriguing epithelial growth properties of contact lenses used as a bandage for patients after pterygium surgery. AIM: To determine the efficacy of culturing human ocular surface epithelial cells on therapeutic contact lenses in autologous serum with a view of using this system to transfer epithelial cells to patients with persistent corneal or limbal defects. METHODS: Excess graft tissue resected from patients undergoing pterygium surgery (n = 3) consisting of limbal epithelium was placed on siloxane-hydrogel contact lenses (lotrafilcon A and balafilcon A). Limbal explants were cultured in media with 10% autologous serum. Morphology, proliferative capacity and cytokeratin profile were determined by phase contrast, light and electron microscopy, and immunohistochemical analysis. RESULTS: Lotrafilcon A contact lenses sustained proliferation and migration from limbal tissue. Cells became confluent after 10-14 days and consisted of 2-3 layers with a corneal phenotype (CK3(+)/CK12(+)/CK19(-)) and a propensity to proliferate (p63(+)). Electron microscopy showed microvilli on the apical surface with adhesive projections, indicating that these cells were stable and likely to survive for a long term. Growth was not observed from limbal explants cultured on balafilcon A contact lenses. CONCLUSION: A method for culturing human ocular surface epithelium on contact lenses that may facilitate expansion and transfer of autologous limbal epithelial cells while avoiding the risks associated with transplanting allogeneic tissue has been developed. This technique may be potentially useful for the treatment of patients with limbal stem cell deficiency.

Bandages↗
PubMed2003

Infectious keratitis associated with daily disposable contact lenses.

PURPOSE: To report two cases of infectious keratitis associated with the use of daily disposable soft contact lenses. METHOD: Two case reports of individuals who developed infectious keratitis while wearing daily disposable soft contact lenses are presented. RESULTS: The first case is that of a 34-year-old woman who had been using daily disposable soft contact lenses for 18 months before she developed a corneal ulcer in her left eye. The cultures grew Pseudomonas aeruginosa, and she was treated successfully with fortified topical antibiotics. The second case describes a 30-year-old woman who had been using conventional soft contact lenses for 5 years before switching to daily disposable soft contact lenses 3 months before presentation. She was found to have a corneal ulcer in her left eye that grew Staphylococcus aureus on cultures, and she responded to topical antibiotic treatment. CONCLUSIONS: Although daily disposable soft contact lenses theoretically have a lower risk of infectious keratitis compared with other lens wear regimens, reports have shown that at least some risk remains. These lenses should be prescribed and used with great care to minimize contact lens-related infectious keratitis.

Adult↗
PubMed2002

Management of pellucid marginal corneal degeneration with rigid gas permeable contact lenses.

PURPOSE: To study the clinical performance of rigid gas permeable contact lenses (RGPCL) in patients with pellucid marginal corneal degeneration (PMCD). METHODS: This retrospective study consisted of 15 patients with clinical PMCD, confirmed by videokeratography (TMS-1, Computed Anatomy, Inc., New York, NY). Information collected from the medical records included patient demographic data, uncorrected visual acuity, refraction, best-corrected spectacle visual acuity, and topographic details, including kerotometry. Twenty-seven of 30 eyes were subjected to several contact lens trials using polymethylmethacrylate (PMMA) contact lenses, using a systematic and consistent approach. After successful contact lens trials, data regarding number of trials, trial time, final contact lens choice parameters, and best-corrected contact lens visual acuity were noted for each patient. During follow-up, visual acuity with RGPCLs, lens fit, and average wearing time were noted. RESULTS: Fifteen patients (30 eyes) with typically inferiorly located pellucid marginal corneal degeneration were included in this study. There were 12 men and 3 women, with a mean age of 39.73 years. Twenty-seven eyes of 15 patients were identified as subjects for multiple contact lens trials, and 24 (88.8%) eyes were successfully fitted with RGPCLs. Best-corrected visual acuity of 6/12 or better with spectacles was achieved in 14 (46.66%) eyes. The average astigmatism was -8.56D, and a majority of the patients with PMCD who were in the contact lens trial had an against-the-rule astigmatism (63.3%). The mean trial time for attempted eyes (i.e., patients with PMCD who successfully underwent the contact lens trials) was 77.7 minutes, and the number of trials required to finalize the choice of contact lenses ranged between 2 and 7. The median base curve for RGP lenses was 7.57, and median diameter was 10.00 mm. Best-corrected visual acuity of 6/12 or better with the final contact lens was achieved in 95.4% of the subjects. After an average follow-up of 22.91 months, one patient was lost to follow-up, and 2 eyes required discontinuation of the contact lenses. The average wearing time among the contact lens wearers at their last follow-up visits was 9.58 hours. Final visual acuity of 6/12 or better was observed in 77.3% of eyes at the end of 22.91 months. CONCLUSION: Large-diameter RGPCLs are better tolerated and lead to significant improvement in visual acuity in inferior PMCD.

Adolescent↗
PubMed1983

Comparison of results obtained with keratophakia, hypermetropic keratomileusis, intraocular lens implantation, and extended-wear contact lenses.

The limited experience with LRK precludes a valid comparison with IOLs and extended-wear contact lenses. Only observations, unsupported by valid statistical analysis, are possible. Some of these observations follow. Technically, LRK is very difficult. In their present form, the classic Barraquer procedures could never be used widely. However, if lenticle banks were to supply preground lenticles, the level of difficulty of LRK procedures would be comparable to IOL implantation. The magnitude of refractive correction possible with LRK compares favorably with that of contact lenses and IOLs. However, the accuracy of achieving a given correction is lower with LRK. Unlike contact lenses or IOLs, LRK induces both regular and irregular astigmatism. The latter accounts, in part, for the delayed visual result with LRK. The percentage of patients with 20/40 or better vision following LRK compares favorably with the percentages for contact lenses or IOLs, whereas the percentage of patients with 20/25 or better vision does not. This is true for at least 1 year following surgery. Compared to extended-wear contact lenses, IOLs and LRK typically require less commitment, fewer postoperative visits, and less expenditure by the patient, in terms of time and money, to achieve full-time correction. Although LRK is associated with a number of postoperative complications, none are known to be intraocular, and there have been no known reports of permanent severe visual loss. In contrast, the patient with an extended-wear contact lens or IOL is permanently at risk to develop sight-threatening complications. This is not the case with LRK, which has no known complications after the early postoperative period. Application of the IOL or extended-wear contact lens to the neonate or pediatric patient is associated with increased risk and difficulty. This may not be true with LRK, especially epikeratophakia. The major advantages of LRK appear to be permanent optical correction without the threat of intraocular or long-term complications and the ability to correct contact lens failures without the necessity of reentering the eye. Its major disadvantage is a slightly reduced visual acuity with delayed visual result. Extended-wear contact lenses, IOLs, and LRK are each unique enough that they should be adjuncts to one another. These corrective modalities should be applied judiciously by the patient-surgeon team to the best advantage of the given patient.

Aphakia, Postcataract↗
PubMedDate not supplied

Clinical evaluation of three bifocal contact lenses.

The ACC, Alges, and Tangent Streak bifocal contact lenses were fit in separate populations of presbyopic patients, some of whom had not previously worn contact lenses. Complete eye examinations were performed on fitting and at 6 and 12 months after fitting to determine how effectively the lenses corrected presbyopic symptoms. Patients were examined for subjective comfort, visual acuity, contrast sensitivity, and by slit lamp. Sixteen of the 24 ACC lens wearers (67%), 23 of 31 Alges lens wearers (74%), and 25 of 27 Tangent Streak lens wearers (93%) wore their lenses comfortably after 12 months. Nine of 18 failures (50%) were successfully refit in one of the other bifocal lenses. Most patients read 20/25 and J1 with contrast sensitivity in the normal range at distance and near. Twelve of 16 patients (75%) with no prior contact lens experience continued to wear the lenses at 12 months. We believe that bifocal contact lenses provide an acceptable alternative for the correction of presbyopia. Lens fitting requirements and patient selection are discussed.

Adult↗
PubMed2006

[Laser ray tracing to measure optical aberrations in eyes with contact lenses].

PURPOSE: To evaluate the impact of disposable soft contact lenses upon visual performance by comparing the optical aberrations of myopic eyes with and without the use of contact lenses. METHOD: The optical aberrations of a set of 18 eyes were measured by a laser ray tracing system, an objective measurement method, enabling comparison of the findings of the naked eye, the eye plus a test lens, and the eye plus a disposable contact lens. RESULTS: There was a large variability among subjects, but the general tendency was that test lenses did not modify aberrations, whereas contact lenses tended to increase the ocular aberrations for large pupils by an average of 40%. There was a lower increase for smaller pupils. CONCLUSION: This study predicts there will be no significant adverse effects on the quality of vision from the use of disposable contact lenses worn under daylight conditions, but a small decline in night vision.

Adult↗
PubMed1985

Fitting gas-permeable contact lenses after penetrating keratoplasty.

Between Sept. 1, 1981, and Jan. 31, 1984, 74 eyes (70 patients) were fitted with gas-permeable Polycon contact lenses and monitored for at least six months (range, six to 33 months; mean, 14 months). The major indications for hard contact lens fitting were astigmatism and anisometropia. Astigmatism in this series ranged from 0 to 17.50 diopters (mean, 7.7 diopters). Most patients achieved visual acuities of 20/40 or better (67 of 74, 90%) with contact lenses. Contact lenses were discontinued in 18% (13 of 74), because of graft rejection in four cases and because of contact lens intolerance in nine cases. Our results demonstrated that gas-permeable hard lenses can be fitted successfully in most patients unable to achieve optimal vision with spectacle correction after penetrating keratoplasty.

Adolescent↗
PubMed2000

Evaluation of two new soft contact lenses for correction of presbyopia: the Focus Progressives multifocal and the Acuvue Bifocal.

The clinical performance of Focus Progressives multifocal contact lenses and Acuvue Bifocal contact lenses was evaluated in a group of 42 presbyopes, with equal numbers of individuals having low, medium, and high spectacle add requirements. Following visual performance assessment with an optimal sphero-cylinder spectacle refractive correction, each individual wore each of the two types of contact lenses in successive random order. Each type of lens was used in a daily-wear mode for a period of 7 to 12 days, with follow-up and/or refitting visits occurring after 2 to 5 days, and again after 4 to 7 days of attempted wear. Testing for all three forms of refractive correction encompassed Snellen acuities at distance and near, Bailey-Lovie acuities under high and/or low ambient illumination conditions at near, intermediate, and far viewing distances, stereoacuity, a timed visuomotor task (needle threading), apparent glare/flare, and the nearwork range of subjectively clear binocular vision. The contact lenses also were evaluated for handling, comfort, distance and near ghosting, subjective visual quality, acceptability for common tasks (e.g., using a phone directory), and personal preferences.As might be expected, distance and near acuity, stereoacuity, and visuomotor task performance were somewhat better with sphero-cylinder spectacle correction than with either of the two types of contact lenses. However, several performance differences between the multifocal and bifocal lenses were noted. The Focus Progressives lenses provided significantly better distance acuity under both high and low illumination conditions, and received significantly higher ratings for visual quality (overall and at distance), comfort, and handling. The Focus Progressives lenses were preferred 5:1 over the Acuvue Bifocal lenses. No differences existed between the lenses with respect to near visual acuities, the perceived quality of the near vision, the nearpoint binocular range, stereoacuity, or the acceptability of vision for common nearwork tasks. The results suggest that although both types of lenses afford presbyopes a viable alternative to spectacles, the Focus Progressives lens is superior in many ways to the Acuvue Bifocal lens.

Journal Article↗
PubMed2001

Rigid gas-permeable contact lenses are a safe and effective means of treating refractive abnormalities in the pediatric population.

PURPOSE: This study examined the safety, efficacy, and tolerance of rigid gas permeable (RGP) contact lenses in a pediatric population. The study also considered the economic impact of RGP contact lens wear in children. METHODS: Retrospectively, we reviewed 12 consecutive charts of children with multiple diagnoses of trauma (n = 5), high myopia (n = 1), surgical aphakia (n = 5), corneal scar (n = 4), and microophthalmia (n = 2) who were considered for RGP contact lenses. RESULTS: Fifteen eyes of 12 patients were originally fit with RGP contact lenses. Ten of 12 (83.3%) children were still wearing their RGP contact lenses after a mean follow-up of 17.8 months. Two of 12 patients (16.7%) stopped RGP use. Two of 10 (20%) patients wore their RGP contact lenses for extended wear. Eight of 10 (80%) patients were successful in daily insertion and removal of RGP contact lenses. There were no adverse events secondary to contact lens use in any patients. An average of 2.18 (range: 0.97-4.55) replacement lenses were needed per patient per 6 month interval. CONCLUSIONS: RGP contact lenses are a safe, effective, and tolerable means of treating refractive abnormalities in the pediatric population. With proper education, families can be successful with daily RGP insertion and removal. RGP contact lenses have the advantage of excellent oxygen transmissibility, low bacterial and protein adherence, and the potential to correct irregular astigmatism. Disadvantages include frequent lens replacement.

Aphakia, Postcataract↗
PubMed2001

Studies on the uptake and release of fluoroquinolones by disposable contact lenses.

PURPOSE: To evaluate the ability of three types of disposable contact lenses to take up and release three kinds of fluoroquinolones in vitro. METHODS: We evaluated three FDA-approved disposable soft contact lenses (1-Day Acuvue, Medalist, and 14UV) for their ability to absorb and release three kinds of fluoroquinolones. Contact lenses were presoaked in fluoroquinolones for 1, 4, and 24 hours, and the uptake was determined by measuring the concentration of fluoroquinolones in the three types of disposable soft contact lenses by high pressure liquid chromatography (HPLC). After uptake, the lenses were placed in fresh saline baths, and release rates from the lenses were determined by measuring the concentration of fluoroquinolones in the saline baths by HPLC. RESULTS: The disposable soft contact lens with the highest uptake of fluoroquinolones was the 1-Day Acuvue. After presoaking, drug concentrations in the 1-Day Acuvue and Medalist were higher than their theoretical saturation concentrations (i.e., the concentration of the fluoroquinolone eye drops [0.3%]). The release rates from the 1-Day Acuvue and Medalist lenses were slower than for the 14 UV lens. CONCLUSIONS: These results indicate that among the lenses tested, the most practical drug delivery system is the 1-Day Acuvue disposable soft contact lens.

Anti-Infective Agents↗
PubMed1997

The effect of high and low Dk/L soft contact lenses on the glycocalyx layer of the corneal epithelium and on the membrane associated receptors for lectins.

PURPOSE: Bacterial adherence or binding to the target cell is a prerequisite for the initial stage of most infections and seems to be mediated by lectin-like ligands on the bacterial surface and specific receptors on the target cell membrane. The purpose of this study was to establish whether contact lens wear under closed eye conditions changes the glycocalyx layer, whether it exposes more lectin receptors than eye closure without a contact lens, and whether wear of low oxygen transmissibility (Dk/L) contact lenses exposes more receptors than high Dk/L contact lenses. METHODS: The eyes of six rabbits under general anesthesia were fit with either a high Dk/L soft contact lens (40 x 10(-9), boundary corrected) or a low Dk/L soft contact lens (2 x 10[-9]) or were left without a lens as controls. All eyes were kept closed by suturing for 24 hours. After removal of the contact lenses, all corneas were excised, put in glutaraldehydeforfixation, rinsed, incubated with plant-derived lectins (wheat-germ agglutinin [WGA]) conjugated with gold particles, and prepared for electron microscopy. Membrane associated gold particles were counted and the results were processed statistically. RESULTS: After 24 hours of lens wear under closed eye conditions, the glycocalyx layer showed physical changes in the form of thinning or compression and signs of biochemical changes reflected as an increase in number of WGA receptors. The average number of membrane associated gold particles per 750 micro length of corneal epithelium in control corneas was 1,287.5 +/- 92.5. Particles were significantly (P<0.001) more numerous after wear of high Dk/L contact lenses (3,230.0 +/- 294.5) and after wear of low Dk/L contact lenses (4,611.3 +/- 223.3). The figure after wear of low Dk/L contact lenses was significantly (P<0.01) higher than the figure after wear of high Dk/L contact lenses. CONCLUSION: Our results indicate that lens wear under closed eye conditions seems to change the corneal glycocalyx layer physically as well as biochemically. Significantly larger numbers of WGA receptors were exposed after contact lens wear than without a contact lens. Significantly more receptors were exposed after wear of low Dk/L contact lenses than after wear of high Dk/L contact lenses. These changes may be of importance in relation to the risk of bacterial keratitis.

Animals↗
PubMed2006

[Profile of medical students from the Universidade Estadual Paulista-UNESP--Botucatu, who wear contact lenses].

PURPOSE: To analyze the ametropy, way of acquisition, the care and complications related to contact lens wear among medical students from Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP). METHODS: Questionnaire applied to students from the 1st to the 6th year of the Medical school of the Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP), forming an analytical cross-sectional survey. RESULTS: 27.4% of the students use contact lenses, and among them 94.8% use soft contact lenses and 98% have negative degree. 46.9% discard their contact lens monthly. 63.9% have an average daily use of 14 hours, 14.1% acquire the contact lenses from optician stores or at pharmacies and 46.5% of the students clean their contact lenses when they put them on and take them off. Regarding complications, 51.0% reported ocular redness; 44.5%, blurred vision; and 42.6%, foreign body sensation, whereas only 4 students reported "keratitis". CONCLUSION: We concluded that the inadequate adaptation that occurs even in users knowledgeable about this issue such as medical students, has increased the risk of complications. This fact indicates that more attention must be paid to contact lens care in order to prevent permanent visual deficit.

Adaptation, Physiological↗
PubMed1993

The effectiveness of daily wear contact lenses for the correction of infantile aphakia.

OBJECTIVE: To evaluate the effectiveness and safety of daily wear contact lenses in the treatment of infantile aphakia. DESIGN: A study of prognosis using a cohort followed up for a mean of 58 months. SETTING: All operations, contact lens care, and follow-up were conducted at a university referral center. PATIENTS: Of 111 children undergoing surgery for cataract between 1980 and 1990, 51 (68 eyes) met the criteria of age younger than 2 years at the time of surgery and of cataract of nontraumatic origin. Patients were evaluated for visual acuity, complications, number of contact lenses worn per year, and changes in contact lens refractive power per month. A subgroup of 28 eyes of patients undergoing surgery before age 7 months and followed up for at least 24 months was studied. INTERVENTION: Following cataract surgery, all patients were fitted with daily wear contact lenses. MAIN OUTCOME MEASURE: Final visual acuity and complications were studied. The distribution of mean contact lens power for each month of age was determined. RESULTS: During the follow-up period, no serious complications were encountered. The visual acuity outcome was better following bilateral cataract surgery than unilateral surgery (P < .001 using chi 2 analysis) and was comparable with that achieved with extended wear contact lenses. CONCLUSION: Daily wear contact lenses were found to be safe and effective in the treatment of infantile surgical aphakia. The daily care was easily learned by the parents.

Aphakia, Postcataract↗
PubMed1993

The role of contact lenses, trauma, and Langerhans cells in a Chinese hamster model of Acanthamoeba keratitis.

PURPOSE: To determine the role of contact lenses, corneal trauma, and Langerhans cells in the development of keratitis caused by Acanthamoeba organisms in Chinese hamsters. METHODS: Various methods were used to induce corneal infections in Chinese hamsters, including application of parasite-laden contact lenses. The role of corneal epithelial defects in promoting parasite binding was examined in vitro in a microscopic binding assay. The role of corneal abrasion in the development of Acanthamoeba keratitis was also examined in Chinese hamsters exposed to parasite-laden contact lenses. Other experiments evaluated the effect of infiltrating Langerhans cells on the incidence and severity of Acanthamoeba keratitis. RESULTS: Corneal epithelial defects promoted extensive parasite binding to abraded corneas compared to intact, nonabraded counterparts. Corneal abrasion was absolutely necessary for the induction of Acanthamoeba keratitis in hamsters infected with contaminated contact lenses. Infection was never detected unless the corneas were abraded before exposure to parasite-laden contact lenses. The presence of Langerhans cells in corneas prevented the development of Acanthamoeba keratitis. CONCLUSIONS: The highest incidence of Acanthamoeba keratitis occurs in corneas expressing epithelial defects and exposed to parasite-laden contact lenses. The presence of Langerhans cells in corneas exposed to parasite-laden contact lenses prevents the development of Acanthamoeba keratitis.

Acanthamoeba↗
PubMed2001

Effects of microwave irradiation on the parameters of hydrogel contact lenses.

Ten brands of hydrogel contact lenses were selected from five of the six British Approved Name lens classification groups to test in vitro the effects of repeated heat disinfection by means of microwave irradiation. Each lens type was tested over a number of cycles corresponding to its scheduled number of wearing days. The total diameter and back vertex power of all 80 test and 12 control lenses were measured at the end of their relevant cycling period. The back optic zone radius, center thickness, and water content were measured for 40 test and 8 control lenses. No clinically significant change was found in any of the 10 brands tested. Statistically significant changes were found in the back optic zone radius of the Frequency 55 group and water content of the Precision UV group. Some discoloration was noted in Ciba Visitint lenses.

Contact Lenses, Hydrophilic↗
PubMed1999

[Therapeutic contact lenses in infant corneal ulcerations].

PURPOSE: We present our own results of treatment in corneal ulcerations with therapeutic contact lenses in 4 infants aged between 3 days to 5 weeks. MATERIAL AND METHODS: Four patients (5 eyes) with deep corneal ulcerations of various origin were treated with soft contact lenses at the Clinic of Pediatric Ophthalmology in Katowice. All eyes received one type of the therapeutic lens. Contact lenses were worn between 8 and 21 days. After application of contact lenses pharmacological therapy was used individually for each patient, according to the result of microbiological tests. RESULTS: All patients were successfully cured. A scar of cornea was observed only in one infant because the contact lens had been used too late. Four infants had no corneal haze after the treatment. CONCLUSION: The best results were obtained using the contact lenses early, during the first days of treatment. Contact lenses caused decreasing of pain and reduced application of medicines. They were a good protection for injured cornea.

Contact Lenses↗