Central-to-peripheral corneal edema during wear of embedded-component contact lenses. Issue 1 (February 2022)

• Record Type: Journal Article
• Authors: Kim, Young Hyun; Lin, Meng C.; Radke, Clayton J.
• Is Part Of: Contact lens & anterior eye. Volume 45:Issue 1(2022)
• Publication Date: 2022-02
• Subjects: Contact lens -- Corneal edema -- Hypoxia -- Corneal metabolism -- Contact-lens embedment -- Oxygen -- Finite-element modeling -- Limbal metabolic support -- Smart contact lens -- Scleral lens -- Soft contact lens; Anterior segment (Eye) -- Periodicals; Contact lenses -- Periodicals; Segment antérieur (Œil) -- Périodiques; Lentilles de contact -- Périodiques; 617.752305
• DOI: 10.1016/j.clae.2021.101443
• Languages: English
• ISSNs: 1367-0484

Abstract

Abstract: Purpose: With active investigation underway for embedded-circuit contact lenses, safe oxygen supply of these novel lenses remains a question. Central-to-peripheral corneal edema for healthy eyes during wear of soft contact (SCL) and scleral lenses (SL) with embedding components is assessed. Methods: Various 2-dimensional (2D) designs of SL and SCL with embedded components are constructed on Comsol Multiphysics 5.5. Local corneal swelling associated with the designed lenses is determined by a recently developed 2D metabolic-swelling model. Settled central post-lens tear-film thicknesses (PoLTFs) are set at 400 μm and 3 μm for SL and SCL designs, respectively. Each lens design has an axisymmetric central and an axisymmetric peripheral embedment. Oxygen permeability ( Dk ) of the lens and the embedments ranges from 0 to 200 Barrer. Dimensions and location of the embedments are varied to assess optimal-design configurations to minimize central-to-peripheral corneal edema. Results: By adjusting oxygen Dk of the central embedment, the peripheral embedment, or the lens matrix polymer, corneal swelling is reduced by up to 2.5 %, 1.5 %, or 1.4 % of the baseline corneal thickness, respectively, while keeping all other parameters constant. A decrease in PoLTF thickness from 400 μm to 3 μm decreases corneal edema by up to 1.8 % of the baseline corneal thickness. Shifting the peripheral embedment farther out towards the periphery and towards the anterior lens surface reduces peak edema by up to 1.3 % and 0.6 % of the baseline corneal thickness, respectively. Conclusions: To minimize central-to-peripheral corneal edema, embedments should be placed anteriorly and far into the periphery to allow maximal limbal metabolic support and oxygen transport in the polar direction (i.e., the θ-direction in spherical coordinates). High-oxygen transmissibility for all components and thinner PoLTF thickness are recommended to minimize corneal edema. Depending on design specifications, less than 1 % swelling over the entire cornea is achievable even with oxygen-impermeable embedments.