<s>[INST] Hello doctor,Are Halloween colored contact lenses safe? Do people who need prescribed contact lenses be using them? [/INST] Hello. Ophthalmologists do not recommend colored contact lenses. However, they may be used occasionally for not more than a few hours. The reason is that compared to regular glasses, most colored lenses have a lesser tendency to allow oxygen to pass through to the corneas, thus causing damage to the corneal cells. This problem does not depend on whether the user is a prescription lens user or not. It depends on the quality of the lens and a few biological variables of the person using them. I hope this helps you. </s>