摘要:

Purpose.To achieve an optimal fit with reverse geometry Contex OK lenses and to determine a time course for and the stability of visual and corneal changes in achieving maximal refractive, corneal curvature, and corneal thickness changes after overnight wear of OK B and D series lenses.Methods.This investigation was conducted under an Food and Drug Administration IDE G000059. Both eyes of 10 subjects were fitted with the lenses, and uncorrected visual acuity, refractive correction, contrast sensitivity, corneal curvature, and corneal thickness were measured at baseline and at 1 day, 1week, 1 month, and 3 months after lenses were worn. Except for baseline, data were collected at four different times during the day, immediately following lens removal and 4, 8, and 12 hours after lens removal.Results.The results from eight subjects showed that uncorrected visual acuity, refractive correction, contrast sensitivity, and corneal curvature all changed significantly (P=0.01) overnight. By the end of 1 week, all corneal and visual changes had reached a maximal level and remained fairly stable during the day. These changes were sustained at 3 months. The epithelial thickness data from four subjects showed that the corneal epithelial thickness was reduced by approximately 19 &mgr;m after 3 months of lens wear.Conclusions.Successful fitting of OK B and D series lenses requires a thorough understanding of the lens–cornea relationship.Full effect of overnight orthokeratology is achieved by the end of 1 week. The visual and corneal changes remain stable for all waking hours of the day and allow patients to enjoy excellent device-free vision (20/20).

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.This review article examines recent studies pertaining to contact lens–associated corneal infiltrates (CLACI) that occur in the absence of culture-proven microbial infection.Methods.The literature was reviewed in regard to the clinical appearance, incidence and risk, etiology, pathophysiology, differential diagnosis, and management of CLACI. Recent insights are presented in the context of future directions for prevention of CLACI.Results.Contact lens–associated corneal infiltrates may manifest in various forms that require careful observational skills to ensure proper diagnosis. Although the reported incidence of CLACI varies widely, even a low percentage of contact lens wearers would constitute a substantial number of affected individuals. Any one or a combination of multiple mechanical, hypoxic, or toxic stimuli associated with contact lens use can induce proinflammatory responses that lead to infiltration of inflammatory cells into the cornea. A number of candidate cytokines, chemokines, adhesion molecules, and so forth have been identified. In addition to differentiation from microbial keratitis, CLACI also should be differentiated from ocular disorders not associated with contact lenses but involving corneal infiltrates and from contact lens–associated disorders that may resemble infiltrates. Management of CLACI can range from simple monitoring of the patient to the use of pharmacologic intervention.Conclusions.The small percentage of affected lens wearers translates into a notable number of individuals who, although not experiencing a vision-threatening event, are inconvenienced by the development of infiltrates. Design of preventive measures for CLACI should focus on the elimination of various mechanical, hypoxic, and toxic stimuli that can induce infiltrates and on the approaches for molecular intervention of the inflammatory cascade initiated by the stimuli.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.The choice of intraocular lens (IOL) implanted by cataract surgeons has significant implications for the effectiveness of the operation and the subsequent need for capsulotomy.Methods.Comparison of pertinent peer-reviewed literature published from 1996 through 2001 obtained from a MEDLINE literature search on biocompatibility indicators and IOLs. This review pertains to routine, uncomplicated cataract surgery, and thus, the findings may not be relative to complicated surgeries. Currently available IOLs were not included in this review if no published data on the IOL were available. However, representative lenses from all the major biomaterial classes were included.Results.Overall results of a comparison of published accounts of posterior capsular opacification, Nd:YAG capsulotomies, anterior capsular opacification, aqueous flare, cellular reaction, capsular adhesion, and capsular stability show a polyacrylic elastomer to be the most highly biointegrated IOLs by the human eye.Conclusions.Most evidence published in peer-reviewed journals suggests a clear IOL choice for cataract surgeons. In the field of implantable medical devices, one device in a category does not usually provide consistently superior performance of its intended function. The ability of the biomaterial to maintain a clear optical axis not only by suppressing the proliferation of lens epithelial cells, and thus inhibiting posterior capsular opacification formation and obviating the need for an Nd:YAG capsulotomy, but also by adhering to and stabilizing the capsular bag is, to date, unmatched by any other IOL available.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To identify perceptions related to the wear and care and of contact lenses and self-evaluation of the knowledge regarding their cleaning and disinfection.Methods.A survey was conducted by interviewing contact lens wearers among health care workers at a university hospital.Results.Two hundred one contact lens wearers were interviewed. The average age was 23.5 years; 69.2% were female and 71.1% were college students. Approximately 55% did not consider themselves good wearers and declared as the main reason the inadequate maintenance of the contact lenses and their cases. Regarding contact lens care, 79.1% of respondents admitted not performing it correctly.Conclusion.Although the interviewees were health care workers, their self-evaluation regarding contact lens care showed unsatisfactory knowledge and practices related to the use and care of contact lenses.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To present a nomogram for spherical rigid gas-permeable (RGP) contact lens fitting in patients with pellucid marginal corneal degeneration (PMCD).Methods.Retrospective review of the medical records of 24 patients diagnosed with PMCD who underwent an RGP contact lens trial at the Bausch & Lomb contact lens center between April 1995 and March 2002 at L.V. Prasad Eye Institute in Hyderabad, India. Data collected included age and sex of patients, duration of presenting symptoms, associated ocular conditions, presenting visual acuity, and degree of astigmatism. For the purpose of analysis, the astigmatism was classified into four groups: group 1, less than 5.00 diopters (D); group 2, 5.00 to 10.00D; group 3, 10.00 to 15.00D; and group 4, 15.00 to 20.00D. The final lens parameters, the patient’s comfort level, and the duration of follow-up were analyzed.Results.Forty eyes of 24 patients were fitted with RGP contact lenses during the study period. Sixteen were male patients and eight were female patients. The age of the patients ranged from 13 to 59 years, with a mean of 35.5 years. Twenty-two (91.7%) patients had typical inferior PMCD, whereas the other two (8.3%) had superior PMCD. The mean corneal curvature was 7.1 mm (range, 5.9–7.8 mm) in group 1, 6.9 mm (range, 6.6–7.9 mm) in group 2, 7.5 mm (range, 6.5–7.8 mm) in group 3, and 7.9 mm (range, 6.8–7.8 mm) in group 4. The mean base curve of the final fitting lens was 6.3 mm (range, 5.7–7.8 mm) in group 1, 6.8 mm (range, 5.9–7.8 mm) in group 2, 7.5 mm (range, 6–8.2 mm) in group 3, and 7.2 mm (range, 6.6–7.8 mm) in group 4. The mean lens diameter of the final fitting lens was 8.7 mm (range, 8.6–10.6 mm) in group 1, 9.5 mm (range, 8.8–10.5 mm) in group 2, 10.2 mm (range, 8.8–11.5 mm) in group 3, and 10.4 mm (range, 8.8–11.3 mm) in group 4. The common fluorescein patterns were central touch with midcentral peripheral pooling in 14 (35%) and dumbbell pattern in seven (17.%). The final visual acuity range with an RGP lens in the four astigmatism groups was 20/40 to 20/20 in group 1, 20/30 to 20/20 in group 2, 20/40 to 20/20 in group 3, and 20/200 to 20/50 in group 4. Twenty-one patients were comfortable with an RGP lens, and the mean duration of follow-up was 13 months. Three patients discontinued lens wear. In one patient, the lens was not stable, and the other two experienced discomfort with their lenses.Conclusions.Spherical rigid gas-permeable lenses are a good option for patients even with advanced PMCD. In patients with astigmatism of less than 10D, a lens with a base curve of 6.0 to 7.0 mm and a diameter of 8.0 to 9.5 mm seems to be a good initial lens for trial, and for patients with astigmatism of more than 10D, a lens with a base curve of 7.0 to 7.5 mm and a diameter of 10.0 to 10.5 mm seems to be a good initial lens.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To benchmark the performance of new-generation silicone hydrogel contact lenses in terms of their in vivo hydration characteristics and to highlight the possible clinical ramifications of any changes observed.Methods.Thirteen subjects (four men and nine women with a mean age of 24.8 ± 5.0 years) wore a silicone hydrogel lens (PureVision, Bausch & Lomb, Rochester, NY) in one eye and a conventional hydrogel lens (ACUVUE 2, Johnson & Johnson Vision Care, Jacksonville, FL) in the other eye for 4 weeks on an extended-wear basis. A gravimetric method was used to determine lens water content and dehydration during the intended lifespan of the lenses.Results.For the PureVision lens, the water content was 38.3% ± 0.9%, 35.2% ± 1.1%, and 35.3% ± 1.7% at baseline and after 2 and 4 weeks of wear, respectively (F=28.4,P<0.0001). For the ACUVUE 2 lens, the water content was 58.1% ± 0.6% and 52.1% ± 1.3% at baseline and after 2 weeks of wear, respectively. Thus, after 2 weeks of wear, absolute dehydration was 2.8% ± 1.8% and 6.0% ± 1.3% for the PureVision and ACUVUE 2 lenses, respectively (t=6.8,P<0.0001). The mass of deposition was calculated to be 568 ± 457 &mgr;g for the PureVision lens and 1,660 ± 499 &mgr;g for the ACUVUE 2 lens (t=5.1,P=0.0003).Conclusions.The ACUVUE 2 lens underwent a greater degree of lens dehydration, causing a reduction in oxygen permeability (3.6 barrer), and deposition after 2 weeks of extended wear. The loss of water from the PureVision lens was paradoxically associated with a 6.0-barrer increase in oxygen permeability after 4 weeks of extended wear.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.Disinfecting agents found in current multipurpose solutions (MPS) may produce low-grade ocular surface insults. This study investigates the potential for carboxymethylcellulose (CMC) to chemically complex residual disinfectants in situ.Methods.The chemical availability of the MPS disinfectant polyhexamethylene biguanide (PHMB) was examined using a spectrophotometric assay. PHMB bioactivity was assessed by survival of bacteria in the presence of MPS with varying amounts of added CMC.Results.Chemical availability of PHMB in water or MPS was reduced within 10 minutes of adding CMC. With the addition of CMC to MPS, survival rates for bacteria improved substantially, depending on the bacterial species, concentration, and exposure time.Conclusions.Carboxymethylcellulose rapidly binds PHMB and reduces its chemical availability and bioactivity. These results suggest a potential cytoprotective effect of CMC on the ocular surface when used before lens insertion.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.Should successful monovision contact lens wearers be refitted with bifocal lenses?Methods.Fifty current monovision lens wearers were fitted with ACUVUE Bifocal contact lenses (Johnson & Johnson Vision Care, Jacksonville, FL). Visual function and subjective vision ratings were assessed with habitual monovision lenses at the first visit and then were repeated at the end of 6 months while wearing bifocal lenses. Lens preference was determined at the end of the 6-month study, and the subjects were called 1 year later to repeat the lens preference questionnaire.Results.Forty (80%) subjects completed the 6-month study; nine discontinued for visual reasons. At the end of 6 months of wear, 68% preferred bifocal lenses and 25% preferred monovision. Of the subjects who were contacted a year later, 53% were still wearing bifocal lenses. High-contrast visual acuity and letter contrast sensitivity at distance was the same for monovision and bifocal lenses, but low-contrast acuity was better with monovision. Intermediate low- and high-contrast acuity and 3-meter and near stereoscopic acuity were better with bifocal lenses. Near high- and low-contrast acuity were better with monovision. All subjective ratings, except near vision in poor lighting, were significantly greater with bifocal lenses.Conclusions.It is possible to refit successful monovision lens wearers with simultaneous vision bifocal lenses, and these lenses should be considered as an alternative method for the correction of presbyopia. In addition, subjective responses to bifocal lenses may not be reflective of visual function measurements.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

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 grewPseudomonas 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 grewStaphylococcus aureuson 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.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To present a case of bilateral methicillin-resistantStaphylococcus aureus(MRSA) keratitis after photorefractive keratectomy (PRK).Methods.Retrospective chart review.Results.A 26-year-old female internal medicine resident underwent an uneventful bilateral PRK. After the procedure, the patient was fit with a bandage contact lens and was prescribed tobramycin 0.3%, fluorometholone 0.1%, and diclofenac sodium 0.1% four times per day. Postoperatively, corneal ulcers were noted in each eye, and the patient was referred for a consultation. Gram stain showed gram-positive cocci. The patient immediately started using vancomycin, 35 mg/mL every half hour, and ofloxacin 0.3% every hour around the clock. Forty-eight hours later, corneal and lid cultures were positive for MRSA. Three months after the infection, there was approximately 40% corneal thinning in the right eye and 10% thinning in the area of the corneal ulceration of the left eye. The patient is awaiting corneal transplantation of the right eye.Conclusions.To our knowledge, this represents the first reported case of bilateral MRSA keratitis after PRK. Methicillin-resistantS. aureusis a potentially serious infectious agent after PRK and may be associated with exposure to a hospital setting. For patients who have had extensive exposure to a hospital environment and are undergoing ocular surgery, we recommend prophylaxis against MRSA. To treat a possible MRSA keratitis, we suggest starting a fourth-generation topical fluoroquinolone every 30 minutes, alternating it with vancomycin 50 mg/mL every 30 minutes, and discontinuing steroid use. A high degree of suspicion coupled with rapid and appropriate treatment may result in improved visual recovery.

ISSN:1542-2321    

出版商:OVID    

年代:2003

数据来源: OVID