How should contact lenses be stored when not in use?

Contact lenses should be stored in a suitable solution specifically designed for contact lens care, which is typically a multipurpose solution or saline designed for the storage of contact lenses. The correct answer highlights the importance of using saline solution for maintaining the lenses' hydration and preventing them from drying out. Saline solution helps to keep the lenses moist, which is crucial for their integrity and comfort during their next use, as dry lenses can become damaged and unwearable.

While water might seem like an obvious alternative to keep lenses moist, it's important to note that it doesn’t have the same antibacterial properties as contact lens solutions and can lead to contamination or other serious complications, such as infections. A dry case is not suitable for storage because contact lenses need to be kept moist to ensure they remain in good condition. Similarly, using a protein remover is not appropriate for long-term storage because it's specifically formulated for removing protein buildup and not meant for preserving lenses when they're not in use.