Are Soft Silicone Hydrogel Contact Lenses More Compliant in a Warm, Hydrated Environment?

Towler, Joseph, Lin, Wen-Pin, Wu, Lo-Yu, Abass, Rowan, Wu, Richard, Fathy, Arwa, Alanazi, Rami, Davies, Jay and Abass, Ahmed ORCID: 0000-0002-8622-4632 (2025) Are Soft Silicone Hydrogel Contact Lenses More Compliant in a Warm, Hydrated Environment? PROCESSES, 13 (10). 3290-. ISSN 2227-9717, 2227-9717

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Abstract

Soft contact lenses are usually characterised at room temperature, yet they function on the eye at body temperature, where their mechanics and optical performance can change. This study investigated whether soft silicone hydrogel lenses become more compliant in a physiological environment. Two silicone hydrogel materials (Definitive 74 and Unisil) were tested at 24 °C and 35 °C using uniaxial tensile and compression methods, with Ogden hyperelastic models fitted and finite element analysis performed on a realistic eye model. Both materials became more compliant at 35 °C, with Definitive 74 showing a larger modulus decrease (0.40 to 0.32 MPa) than Unisil (0.73 to 0.70 MPa). Finite element simulations indicated that these temperature-driven changes in compliance significantly affected refractive power, especially when the lens base curve exceeded the corneal radius by more than 5%. These findings demonstrate that soft silicone hydrogel lenses are indeed more compliant in a warm, hydrated environment, highlighting the need for physiologically relevant testing to inform design, fitting strategies, comfort, and vision outcomes.

Item Type:	Article
Uncontrolled Keywords:	hydrogel, silicone hydrogel, contact lenses, mechanical properties, temperature, finite element analysis, element-specific model, Definitive, Unisil
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Engineering Faculty of Science & Engineering > School of Engineering > Materials, Design and Manufacturing Eng
Depositing User:	Symplectic Admin
Date Deposited:	15 Oct 2025 08:44
Last Modified:	23 May 2026 10:37
DOI:	10.3390/pr13103290
Open Access URL:	https://www.mdpi.com/2227-9717/13/10/3290
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3194843
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