Microbial Contamination of Contact Lens Storage Cases During Daily Wear Use.

PURPOSE: To evaluate contact lens (CL) storage case contamination when used with four different CL care solutions during daily wear of three different CL materials. METHODS: A parallel, prospective, bilateral, randomized clinical trial (n = 38) was conducted. Subjects were randomly assigned to use one of three CL materials (etafilcon A, senofilcon A, or galyfilcon A) on a daily wear basis. Subsequently, each subject randomly used one of four different CL care solutions (Biotrue, OPTI-FREE PureMoist, RevitaLens OcuTec, and CLEAR CARE) for 2 weeks, along with their respective storage cases. After every 2-week period, their storage cases were collected and the right and left wells of each storage case were randomized for two procedures: (1) microbial enumeration by swabbing the storage case surface and (2) evaluation of biofilm formation (multipurpose solution cases only) using a crystal violet staining assay. RESULTS: More than 80% of storage cases were contaminated when used in conjunction with the four CL care solutions, irrespective of the CL material worn. Storage cases maintained with CLEAR CARE (mean Log colony forming units (CFU)/well ± SD, 2.0 ± 1.0) revealed significantly (p < 0.001) greater levels of contamination, compared to those maintained with Biotrue (1.3 ± 0.8) and RevitaLens OcuTec (1.2 ± 0.8). Predominantly, storage cases were contaminated with Gram-positive bacteria (≥80%). There were significant differences (p = 0.013) for the levels of Gram-negative bacteria recovered from the storage cases maintained with different CL care solutions. Storage cases maintained with OPTI-FREE PureMoist (0.526 ± 0.629) showed significantly higher biofilm formation (p = 0.028) compared to those maintained with Biotrue (0.263 ± 0.197). CONCLUSIONS: Levels of contamination ranged from 0 to 6.4 Log CFU/storage case well, which varied significantly (p < 0.001) between different CL care solutions, and storage case contamination was not modulated by CL materials.

Clinical performance and Willingness To Pay for soft toric contact lenses in low and moderate astigmats.

PURPOSE: To determine clinical performance and the 'Willingness To Pay' for toric vs. spherical soft contact lenses in an astigmatic population. METHODS: In the clinical study, subjects with binocular low to moderate astigmatism (-0.75DC to -1.50DC) wore pairs of soft toric (Biofinity toric) and spherical (Biofinity) contact lenses in random sequence. Visual acuity (high and low contrast, monocular and binocular), subjective comfort and subjective vision were recorded. In the economics study, first subjects who had participated in the clinical study were presented with a series of randomised economic scenarios in order to determine their Willingness To Pay a premium (i.e. an increase) for toric lenses. Then, a similar set of scenarios were presented to a much larger group of online respondents and again, Willingness To Pay was established. RESULTS: For the four measures of visual acuity, the Biofinity toric lens out-performed the Biofinity spherical lens by 0.6 to 1.1 lines.. Subjective vision performance was statistically significantly better with the toric lens for the distance task only. Comfort scores were not significantly different. Similar findings for Willingness To Pay were established for the clinical subjects and for the online respondents. The Willingness To Pay premium (additional fee) for a monthly supply of toric lenses (over spherical lenses) was between £13 and £16, if a toric lens provides better vision and similar comfort, as shown in the clinical study. CONCLUSION: Consumers are willing to pay a monthly premium of around 50% to benefit from the typical experience of better vision and similar comfort for toric vs. spherical lenses. The level of additional cost for toric lenses compared to their spherical equivalents is less than this in the market, so eye care professionals should consider that toric lenses are delivering a greater clinical return than anticipated by wearers for the relatively small increase in price.

Using face masks with spectacles versus contact lenses.

PURPOSE: To test the hypothesis that various subjective ocular and task-related parameters associated with wearing a face mask would be better in neophyte contact lens (CL) wear compared to habitual spectacle (Sp) wear. METHODS: Thirty participants were randomised to continue in Sp (n = 15) or wear somofilcon A daily disposable CL (n = 15) ('group'). A surgical face mask (Type II R) was worn for at least one hour per day on four or more days per week. After two weeks, participants completed the Quality of Life Impact of Refractive Correction Questionnaire (QIRC), a two-part face mask usability questionnaire and graded ocular-related symptoms using 0-100 visual analogue scales. RESULTS: There was no difference between groups for overall QIRC score but some individual question scores reflected better quality of life in the CL: 'outdoor activities', 'keep fit' and 'able to do things' (all p < 0.05). Differences in favour of the CL were seen for the following in the face mask usability questionnaire: 'breathing', 'heat', 'comfort on ears', 'overall comfort', 'walking', 'driving', 'reading', 'computer use', 'exercising' and 'socialising' (all p < 0.05). Significant differences were also seen for the 0-100 VAS symptoms probing vision quality in favour of the CL: glare, distance and near vision, fogging, restricted field of view and peripheral blur. CONCLUSION: This work supports anecdotal reports that CL are a better vision correction option than Sp when used in conjunction with a face mask. Participants reported a range of benefits to the CL/face mask combination for vision-related symptoms, breathing and heat-related symptoms and a number of day-to-day activities including walking, driving and exercising. All of the benefits relating to the CL are likely to result in improved adherence to face mask use. Overall, the findings of this work suggest that where possible, CL should be the preferred vision correction option for people using face masks.

Comparative Evaluation of Three Abutment-Implant Interfaces on Stress Distribution in and Around Different Implant Systems: A Finite Element Analysis.

AIM: This study was conducted to compare and evaluate the effect of three abutment-implant connections on stress distribution around three different implants under similar material properties and loading condition using finite element analysis (FEA). MATERIALS AND METHODS: Three different types of implant-abutment connections were selected. The features of these connections are Sample A: Tri-channel internal connection (Nobel Biocare); Sample B: Internal conical-hex Morse Taper (ADIN); and Sample C: Internal octa-Morse taper method (Osstem). The following softwares - ANSYS Version: 14.5 for FEA; Meshing software: Hypermesh 11; and CATIA: to produce computerized models of implants and for mandibular modeling were used. The implants were scanned with a high-quality scanner. All the above data were used to produce computerized models by CATIA software. Within the implant system, finite element method modeling was performed by implementing bonded conditions on the abutment-implant interfaces implementing four different load conditions. The computerized model was transferred to ANSYS software. A statistical analysis was done to compare the groups. RESULTS: The samples were evaluated using three-dimensional FEA analysis. It was found that stress at 100 N, 100 N with 15° tilt, 300 N, and 300 N with 15° tilt was found to be highest in Sample A followed by Sample C and Sample B, and the difference was statistically insignificant. CONCLUSION: Within the limitations of the present study, the tri-channel internal connection showed maximum stresses and least by the internal conical-hex Morse Taper and internal octa-morse taper connection.