Sebastian Marx

A novel in-vitro method for assessing contact lens surface dewetting: Non-invasive keratograph dry-up time (NIK-DUT)

PURPOSE This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting. METHODS Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE® PureMoist® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event. RESULTS Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r=8.5mm, e=0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions. CONCLUSIONS NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses.

88 Improvement of optical business with contact lens supported spectacle dispensing in Germany

Purpose: To explore the contribution of the International Association of Contact Lens Educators (IACLE) towards the status of CL education in Asia. Method: In the early nineties contact lens (CL) education was not standardized in Asia. IACLE’s projects include providing a comprehensive IACLE CL Curriculum (ICLC), the biannual IACLE Accreditation Exam, educational meetings and “train-the-trainer” programmes, as well as student trial exams. Results from these initiatives were analysed for a ten year period with results of an IACLE membership survey. Results: IACLE has established 118 Resource Centers in Asia, all of which make use of the IACLE curriculum (ICLC). IACLE reaches 8728 students and the student trial exam has a steadily increasing pass rate of students in China by 12%, in India by 32% and in Korea by 20%. The pass rate of educators participating in the accreditation exam has increased by 8%. The number of CL patients seen before graduation by a student have increased to: India 70 (SCL: 41, RGP: 29), China 16 (SCL: 10, RGP: 6) and Korea 39 (SCL: 21, RGP: 18). Students at the schools surveyed can detect most of the CL complications presented: India (68%), China (60%) and Korea (53%). Conclusions: IACLE has played an important role in standardizing and improving CL education across not well regulated Asian countries. Establishing a very strong educational base is essential in ensuring that future practitioners confidently fit and manage their contact lens patients.

16 Thickness of spherical and toric SCLs measured in vitro by Scheimpflug's principal for determination of the Dk transmissibility values

Purpose: The importance of meeting presbyopic patient’s needs grows with the aging population. Satisfaction with the overall contact lens wearing experience can be impacted by material characteristics and optical design. The purpose of this study was to evaluate satisfaction of adapted omafilcon A (Proclear) Multifocal (PM) wearers and balafilcon A (PureVision) Multi-Focal (PVMF) wearers. Method: 150 PVMF and 107 PM wearers who had been wearing their respective lenses for at least three months completed an on-line survey conducted by an independent market research firm. Experiential factors most impactful to multifocal wearers in driving them to speak to their practitioners about switching brands were assessed. Specific lens performance attributes experienced by the wearers were also queried. Results: The top five influencers of switching brands were comfortable throughout the day, clarity of mid-range, near, and far-distance vision, and ease of transition between near and far-distance. PVMF wearers were more satisfied with their complete lens wearing experience, PVMF 91% vs. PM 82% (p<0.05). Composite ratings for vision and comfort also favored PVMF over PM, 81% vs. 68% and 91% vs. 79%, respectively (p<0.05%). Conclusions: While satisfaction with comfort is higher than with vision quality, vision-related attributes are the most common reason patients would ask about switching brands. Most multifocal wearers were satisfied with their lenses; however, PVMF wearers were more satisfied with their complete multifocal experience when compared to PM wearers. With vision and comfort favoring PVMF, differences in material and optical design characteristics likely contributed to greater satisfactionwith the multifocal experience.