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To avoid risks of mucosal infection from contact lenses removal, a contact lens plunger is often used. Given various types of contact lens plungers available on the market, no study has yet been done on mechanical effects of the contact lens plunger on contact lens removal. Here, this study used finite element analysis to investigate the effects of plunger size and plunger position on the removal of soft and rigid gas permeable (RGP) contact lenses. First, we established finite element analysis models for the plunger, contact lens, cornea, and aqueous humor. The plunger is made of mostly silicone rubber, and the contact lenses are mainly made of soft and hard material. The part of the plunger used for removal was located either at the central or the edged position, with pulling 1 mm distance. The main parameters observation indicators of in this study were the reaction force at the fixed end of the cornea, aqueous humor, the von Mises stress of the plunger, the contact lenses, and the cornea. Results of this study showed that when a plunger of a larger diameter was used, the reaction force of the plunger was also larger, especially when applied to RGP lenses, which required a slightly larger force (∼0.27 N). Also, when removing a RGP lens from the edge, there was a greater stress at the edge of the contact lens (2.5799 MPa), and this caused a higher stress on both the cornea (0.0165 MPa) and the aqueous humor (0.00114 MPa). When using a plunger with a larger diameter to remove a RGP lens, although a larger force required, the relatively larger contact area likely reduced the stress on the cornea and aqueous humor, thereby reducing the risk of eye injury. In addition, when removing a RGP lens, the results of this study recommended it to be removed from the plunger edge, as that facilitated the removal of contact lens. [ABSTRACT FROM AUTHOR]

Objective: Iatrogenic vocal fold paralysis is an important issue in laryngology, yet there are few population-based studies regarding the epidemiology. This study used a nationwide population-based claims database (the National Health Insurance Research Database) to investigate the epidemiology of iatrogenic unilateral and bilateral vocal fold paralysis (UVFP/BVFP) among the general adult population in Taiwan. Method: This study analyzed patients (20-90 years old) who underwent thyroid, parathyroid, thoracic, cardiac, or anterior cervical spine operations with vocal fold paralysis among adults in Taiwan from January 1, 2007 to December 31, 2013. The codes for vocal fold paralysis were defined by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). Claims data in the Taiwan National Health Insurance Research Database were used. Results: The most commonly performed operations which were related to vocal fold paralysis in Taiwan were, in descending order of frequency, thyroid, cervical spine, cardiac, thoracic (esophagectomy), and parathyroid operations. The operations that put laryngeal nerves at risk (ONRs) most commonly associated with a diagnosis of UVFP were, in descending order of frequency, thoracic, thyroid, parathyroid, cardiac, and cervical spine. For both UVFP and BVFP, the most commonly associated age group was 51 to 60. For both UVFP and BVFP, the more commonly associated sex was women. Increased length of stay was associated with a higher incidence of UVFP and BVFP. Charlson medical co-morbidity index (CCI) was not associated with UVFP but BVFP was associated with higher Charlson medical co-morbidity scores. Conclusions: Thyroid operations, age 51 to 60, longer hospital stays are associated with vocal fold paralysis. Overall women are more surgically affected than men. This is the first population-based study of iatrogenic vocal fold paralysis. [ABSTRACT FROM AUTHOR]