How does increasing modulus affect the stiffness of a contact lens?

How does increasing modulus affect the stiffness of a contact lens?

• A. Stiffer
• B. Softer
• C. More flexible
• D. Less durable

Answer: (A)

Modulus, specifically Young's modulus, is a measure of how resistant a material is to elastic deformation under load. When modulus increases, the material resists bending and stretching more, so it becomes stiffer. In contact lenses, a higher modulus lens is less able to conform to the corneal surface and eyelid movements, and it feels more rigid during handling and wear. The bending stiffness of a lens increases with the modulus (and with thickness to the third power), so increasing modulus directly makes the lens stiffer.

Modulus, specifically Young's modulus, is a measure of how resistant a material is to elastic deformation under load. When modulus increases, the material resists bending and stretching more, so it becomes stiffer. In contact lenses, a higher modulus lens is less able to conform to the corneal surface and eyelid movements, and it feels more rigid during handling and wear. The bending stiffness of a lens increases with the modulus (and with thickness to the third power), so increasing modulus directly makes the lens stiffer.