Summarize this article in one sentence.
Many companies manufacture products specifically designed to prevent glasses from fogging. These are either a spray or gel and, when applied directly to your lens, will reduce fog by forming a barrier that protects against moisture condensing. Most products require you to spray both sides of the lens, let dry, and wipe clean with a soft, dry cloth. Some products suggest longer dry times, while others require the spray or gel be rinsed off prior to wiping. Check product packaging for specific instructions. These pre-treated cloths are convenient and easy to use. Simply wipe both sides of the lens using the pre-packaged wipe. These wipes are made for only one use, so just throw it away when you're finished. Check with your eye doctor about the availability and cost of applying a one-time coating to your lenses to permanently prevent fog. This option may be particularly useful when there are drastic and/or frequent temperature changes or if the fog creates a safety hazard. Be prepared to leave your glasses for a few days and spend between $50-$100.

Summary:
Purchase an anti-fog product to treat your glasses at home. Purchase anti-fog wipes for on-the-go protection. Invest in a professional anti-fog treatment for a longer lasting solution.