Naphazoline is a medication used to relieve redness, swelling, and itching of the eyes caused by allergies, irritation, or infection. However, during the manufacturing process, impurities may be introduced, which can affect the safety and efficacy of the drug. These impurities may include residual solvents, degradation products, and other contaminants that can potentially cause adverse effects. It is important to monitor and control the levels of these impurities to ensure the quality and safety of the final product.