High water content in contact lenses can lead to which of the following?

High water content in contact lenses is primarily associated with the balance of oxygen transmission and moisture retention. Lenses with high water content tend to allow more oxygen to pass through to the cornea, which is beneficial. However, they can also lead to fluctuations in vision due to changes in the lens shape and stability when they absorb moisture from the environment or tear film. This can create variable optical properties, causing transient changes in the clarity or focus of vision.

The correct choice reflects the reality that while higher hydration levels can provide certain benefits, they can also contribute to optical instability as hydration can affect the refractive index and surface characteristics of the lens. Fluctuations in vision associated with high water content lenses may also occur owing to dehydration during wear, which is particularly common in dry environments or extended wear scenarios.

Other options like anoxia and hypoxia refer to the deficiency of oxygen, typically linked with low oxygen permeability and lens materials rather than high water content. Ametropia pertains to issues related to refractive errors and is not directly influenced by the water content of the lenses.