Causes of lens flexure may include?

The correct answer, which states that all of the options contribute to lens flexure, reflects the multifactorial nature of this phenomenon in contact lenses.

Lens flexure can occur due to various influences. The pressure exerted by the upper eyelid, for instance, can significantly impact a contact lens, especially in cases where the lens is soft or has specific geometries. When the upper lid moves, it can apply pressure to the lens, causing it to flex and potentially change its fit on the cornea.

High DK lens materials are also relevant because they are designed for increased oxygen permeability. While this can be beneficial for the health of the cornea, such materials can sometimes have a different behavior under pressure compared to lower DK materials, which may lead to flexure in certain situations.

Furthermore, the apical clearance lens design is another factor leading to lens flexure. This design allows for some space between the lens and the cornea, which can help with tear exchange but might also permit more flexure under certain conditions.

Thus, each of these elements—pressure from the upper lid, the characteristics of the lens material, and the design of the lens—can all contribute to the overall phenomenon of lens flexure, making the conclusion that all