What is a common effect of wearing contact lenses too long?

Wearing contact lenses for too long can lead to corneal hypoxia, which is a condition resulting from insufficient oxygen reaching the cornea. Contact lenses sit directly on the surface of the eye, and while they are designed to allow some oxygen to pass through, extended wear can exceed the lens's oxygen permeability limits. This can result in the cornea becoming swollen due to fluid retention, ultimately leading to discomfort and potential long-term damage.

When the cornea is deprived of oxygen, it can also increase the risk of complications such as neovascularization, where new blood vessels grow into the cornea as a response to hypoxia. This condition emphasizes the importance of adhering to the manufacturer's recommended wear schedule and ensuring proper lens hygiene to maintain healthy eyes and optimal vision.

In contrast, the other choices do not represent a common effect of prolonged contact lens wear. Improved vision and comfortable wear are typically associated with the appropriate use of lenses, while reduction in tear film stability can be a factor, but it is not as direct a consequence of wearing lenses for too long as corneal hypoxia is.