The CLAO journal : official publication of the Contact Lens Association of Ophthalmologists, Inc最新文献

Purpose: This study evaluates lens care using the PuriLens System, an advanced way to clean and disinfect soft hydrophilic lenses using subsonic agitation and UV radiation, respectively.

Methods: A two-period crossover lens cleaning and safety investigation was conducted using 80 patients. Disinfecting efficacy was tested in accordance with standard FDA protocols. Lens compatibility was studied with Group I and Group IV lenses during the equivalent of a 6-month care regimen by measuring: lens power, base curve, wet diameter, refractive index, clarity, and tint. Safety was evaluated through slit-lamp findings, wearing time, comfort, and visual acuity.

Results: The mean wearing time of patients in the study was 13.79 hours. No slit lamp findings greater than grade 2 were noted. Visual acuity was 20/25 or better in 92.5% of examinations. None of the patients lost more than two lines of acuity. Lens surface evaluation showed no deposits (grade 0) to very slight deposits (grade 1) in 94.4% of examinations. Lenses cleaned with the PuriLens System were cleaner by a statistically significant margin (P=0.02) compared to lenses digitally cleaned with a leading multi-purpose solution (ReNu, Bausch & Lomb). Overall, neither the Group I nor Group IV lenses were affected after 180 cleaning cycles.

Conclusions: The PuriLens System provides automatic lens care compliance, superior antimicrobial efficacy, and eliminates the need for daily digital cleaning.

Purpose: To determine the influence of a daily wear rigid gas permeable (RGP) high DK lens (CIBA Vision Persecon92E, Dk=92 x 10(-11)) on corneal endothelial cell density (ECD).

Methods: A prospective longitudinal, follow-up study was conducted. Variations in corneal ECD during the first year were reported. For this purpose, the endothelium of 97 eyes of 57 unadapted subjects were compared by specular microscopy before and after 1 week (n= 74), 1 month (n=67), 3 months (n=51), and 1 year (n=23) of wearing contact lenses.

Results: There was a significant decrease in cell density vs age (r=-0.28, P=0.005). ECD significantly increased 1 week (3.6%) (P=0.001), 1 month (3.6%) (P=-0.003), and 3 months (4.5%) (P=0.003) after contact lens wear. One year after the lens fitting, a similar but not significant increase was found. While ECD increase was insignificant with initially high ECD subjects (>2700 cells/mm2), subjects with low ECD initially (<2700 cells/mm2) showed a significant increase in ECD in all time intervals.

Conclusions: In the 1 week RGP contact lens wearing period, the endotheliums with low ECD probably adapted to a new oxygen environment by cell migration or mitotic activity. The increased ECD was perhaps related to the daily wear schedule in which the oxygen partial pressure was sufficient.

Purpose: There has been increasing awareness of the need for more powerful contact lens disinfectants, ideally having low toxicity and allergenicity to ocular tissue. Opti-Free Express with ALDOX Multi-Purpose Disinfecting Solution (MPDS) was recently marketed as a new multi-purpose disinfecting solution for soft contact lenses. MPDS contains two antimicrobial agents, polyquaternium-1 and myristamidopropyl dimethylamine, to broaden the range of antimicrobial activity. The purpose of this study was to evaluate the antimicrobial activity of MPDS against microorganisms that have been reported as contact lens and lens case contaminants and causative agents of microbial keratitis.

Methods: MPDS was challenged with high numbers of gram-positive and gram-negative bacteria, yeast, mold, and Acanthamoeba. Several lots of product were challenged with at least three separate inocula of each isolate. After exposure to the disinfecting solution, a sample was removed from the product and plated for survivors by suitable recovery methods. The plates were incubated and the number of survivors was enumerated.

Results: The results showed that MPDS was bactericidal, fungicidal and amoebicidal against an extensive variety of environmental contaminants of lens care accessories and ocular pathogens. MPDS was capable of killing a broad spectrum of microorganisms. The log reduction exceeded the primary criteria for disinfecting products and produced a notable reduction of other clinical and environmental isolates as well.

Conclusions: Opti-Free Express MPDS contains antimicrobial agents that can kill an extensive spectrum of many different types of microorganisms that may contaminate contact lenses and solutions.

Purpose: To evaluate the therapeutic efficacy of disposable contact lenses in management of complications after keratoplasty.

Methods: Twenty-eight patients with various post keratoplasty complications were fit with disposable contact lenses (45% Vifilcon A and 55% water content). Indications for lens use included persistent epithelial defects, wound leak, graft edema, dry eye and protection of normal corneal epithelium.

Results: Success was obtained with the therapeutic use of disposable lenses in 20 of the 28 cases. The best results were seen in maintenance and restoration of healthy ocular surface and small wound leaks. Stromal graft edema with no epithelial involvement was the major area of therapeutic failure.

Conclusions: Disposable contact lenses are an attractive low cost option in the management of complications after keratoplasty. They are particularly useful in maintaining a healthy ocular surface, providing symptomatic relief and avoiding resurgery in patients with small wound leaks.

Purpose: Previous studies have shown that 1-hour closed-eye contact lens wear with a low-Dk lens causes a significant reduction in corneal pH and an increase in epithelial permeability. In the present study, we evaluated the effects of super-high-Dk/t soft lenses on corneal epithelial barrier function and stromal pH.

Methods: Corneal thickness was measured by optical pachometry, while epithelial permeability and stromal pH were measured by fluorophotometry. A paired-eye design was used in which one eye was randomly allocated to wear a high-oxygen-permeable soft lens (CIBAVision Focus/NIGHT & DAY (Dk/t= 175) while the other eye did not wear a lens.

Results: After 1-hour closed-eye lens wear, neither the difference in corneal swelling (P = 0.206) nor the permeability (P = 0.055) between both eyes was significantly different. The mean pH values under open-eye conditions were 7.66 vs. 7.57 for the treatment and control eyes, respectively (P = 0.082), dropping to 7.27 vs. 7.25 after 1-hour eye closure (P = 0.283).

Conclusions: Although our results are limited to a 1-hour observation period, they do provide evidence that high-Dk materials may eliminate corneal acidosis and reduced epithelial barrier function that accompany closed-eye contact lens wear with lower-Dk soft lens materials.

Purpose: To evaluate the usefulness of measuring corneal topography intraoperatively by Intraoperative PAR Corneal Topography System (IOPAR CTS) to predict the postoperative topographical changes in patients undergoing refractive surgery.

Methods: Topographical measurements of 9 eyes of 9 patients were taken by IOPAR CTS: 6 immediately after Intrastromal Corneal Ring Segments (ICRS) placement surgery and 3 immediately after Photorefractive Keratectomy (PRK) surgery. The topographical images taken by IOPAR CTS were analyzed to determine the quality of the image produced and the correlation of the keratometric data from the central 3 mm of cornea with measurements taken from an autokeratometer (Auto-Km) and the EyeSys Corneal Analysis System (CAS) for the same eyes taken three months following the procedure.

Results: At the 3-month postoperative exam, the correlation coefficients for flat (K1), steep (K2), and average keratometry (AK) readings produced by the Auto-Km and the EyeSys CAS were quite high. However, the correlation coefficients for K1, K2, AK, As or steep meridian axis (Ax) readings taken intraoperatively by IOPAR CTS were quite low when compared to the readings taken by either the Auto-Km or EyeSys CAS three months postoperatively.

Conclusion: We found IOPAR CTS, relatively difficult to perform in the operating room during refractive surgical procedures and not useful clinically in predicting the postoperative topographical changes induced by ICRS or PRK procedure. Further studies are required to establish the efficacy and reproducibility of the instrument.

Purpose: To present the diagnostic and therapeutic challenges of ophthalmia nodosa secondary to tarantula hairs.

Methods: We present a case of a 28-year-old male with a one-week history of skin rash followed by ocular irritation, and blurring of vision after handling a Chilean rose tarantula. A Medline-guided literature search was performed to review the current and historical knowledge of ophthalmia nodosa. The clinical presentation and therapeutic options in ophthalmia nodosa were reviewed.

Results: Ophthalmia nodosa is a granulomatous, nodular reaction to vegetable or insect hairs including tarantula hairs. Tarantula hairs can cause inflammation in all levels of the eye, from conjunctiva to retina. Therapy includes surgical removal of offending hairs and medical management of inflammation.

Conclusions: Although tarantulas are considered harmless pets, ophthalmia nodosa is a potential danger when handling a tarantula. Furthermore the management of exposure to tarantula hairs can be difficult.

Purpose: The world of computerized videokeratoscopy is continually evolving. Computerized videokeratoscope contact lens programs boast the capability to accurately design final rigid gas permeable (RGP) lens parameters and simulate contact lens fluorescein patterns. We evaluated the EyeSys System 2000 Pro-Fit software (v. 4.0) and Humphrey Atlas MasterVue Contact Lens Module (v. A6) for efficiency and accuracy in fitting RGP contact lenses on normal subjects.

Methods: Balanced manifest refractions, slit lamp examinations, and computerized topographical analysis with RGP module lens fitting were performed and compared for all eyes. Lens parameters were chosen after an optimal simulated fluorescein pattern was achieved by either accepting the initially recommended default lens or a modification. Final lens parameters were based on clinical performance.

Results: With the Humphrey Atlas software, which uses a default topographic tear clearance fitting protocol set by the manufacturer, 24/50 (48%) eyes required modifications to the default fitting parameters based on the simulated fluorescein patterns. Nine of 50 eyes (18%) required further modifications once the RGP lens was dispensed. The EyeSys Pro-Fit software, which allows a custom tear clearance fitting protocol set by the user as default, required modifications to 20/35 eyes (57.1%) from default fittings provided by the system. Six of 35 eyes (17.1%) required subsequent modifications once the RGP lens was dispensed. Comparison of the EyeSys to Humphrey modules revealed no significant difference in efficiency (P=0.51), defined as any changes required to the default parameters; however, the user made more modifications to the EyeSys module from the default setting. There was no significant difference in final success rates between EyeSys (82.9%) and Humphrey (82%) systems (P=1.00).

Conclusion: Although both topography guided contact lens modules offered accuracy in RGP fitting, a user programmed default (EyeSys) protocol did not improve efficiency in RGP lens parameter selection compared to a manufacturer programmed default module (Humphrey). The need for a knowledgeable contact lens fitter remains to guide the systems in achieving the optimal fit.

Purpose: To determine if hydrogel lens water content decreases over wearing periods of up to four weeks; that is, demonstrate an 'ageing' effect.

Methods: Six subjects (4 males, 2 females; age range: 34.8 +/- 11.0 years) wore each of the following lenses for one month: Acuvue, Frequency 38, Gentle Touch and Proclear. Pre-insertion and post-removal lens water content was measured daily by the subjects using an Atago CL-1 Soft Contact Lens Refractometer for a 28 day period. Post-insertion and pre-removal comfort was recorded over the same period.

Results: A significant lens ageing effect was noted whereby the pre-insertion lens water content decreased significantly over the 28 day cycle for all lenses (P < 0.05). The pattern for daily dehydration remained consistent for the 28 day period for the Acuvue lens and the Gentle Touch lens but decreased for the Frequency 38 lens and the Proclear lens. Comfort decreased significantly by the end of the day for three of the four lens types investigated.

Conclusions: It is apparent that the extent of lens dehydration changes over time, and that this pattern of change is different for different lens types. The associated loss of oxygen performance with dehydration is demonstrated. These data will assist practitioners in understanding the clinical effects of soft lens dehydration over time.