کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
810886 1469123 2013 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mechanical performance of hydrogel contact lenses with a range of power under parallel plate compression and central load
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی پزشکی
پیش نمایش صفحه اول مقاله
Mechanical performance of hydrogel contact lenses with a range of power under parallel plate compression and central load
چکیده انگلیسی


• Hydrogel contact lenses of a range of optical power are characterized by parallel plate and central load compression.
• A numerical model is used to extract material parameters.
• Lens power/thickness profile significantly influences the apparent stiffness that in turn affects the degree of comfort.

When a contact lens is compressed between two parallel plates (PPC) or under a central load (CLC), the constitutive relation depends not only on the mechanical properties such as elastic modulus, E, of the hydrogel materials, but also the lens power, d, or thickness variation, h(ϕ0), along the meridional direction ϕ0. Hyperopic lenses (d>0) are thicker at the apex along the optical axis and thin out gradually along the meridian, while myopic lenses (d<0) are thinnest at the apex. Mechanical deformation is quantified by the inter-relationship between applied force, F, vertical displacement of the external load, w0, contact or dimple radius, a, and the deformed profile, w(r). Force responses show that lenses with positive d are apparently stiffer in the initial loading but become more compliant as load increases. Conversely, lenses with negative d are more deformable initially and becomes gradually more resistant to loading. This is consistent with the theoretical shell model using the same E. The mechanical behavior has significant impacts in defining the degree of comfort of contact lenses as well as the lens adhesion to the corneal epithelium.

Figure optionsDownload high-quality image (109 K)Download as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of the Mechanical Behavior of Biomedical Materials - Volume 22, June 2013, Pages 59–64
نویسندگان
, , , ,