One way to improve vision is to wear glasses. However, glasses can hamper one's ability to participate in different activities. Many people also consider glasses to be less attractive. Contact lenses are a more attractive option. They are placed over the cornea and are thus in "contact" with the eye. These lenses are made of plastic or other synthetic materials.

Leonardo da Vinci is believed to have been the first to sketch some ideas for contact lenses, way back in 1508. The first wearable lens was created by a German glassblower, F. E. Muller, in 1887.

You need the advice of an ophthalmologist, optometrist or optician to choose the right contact lenses, and a valid prescription to own and use contacts. This is a must even if you do not need vision correction. According to the FDA, contact lenses are medical devices, as these are put in the eye. One pair of lenses need not fit all, as eyes differ in shape and react differently to the lenses.

Contact lenses are mainly of two types"soft and hard. Soft contacts are also known as disposable contact lenses. These lenses are mostly soft plastic and water. Hard lenses, also known as Rigid Gas Permeable lenses, or RGPs, are made of silicone.

It is easier to wear and get used to soft lenses. However, soft lenses allow less oxygen to pass through. Hard contact lenses let more oxygen through and are preferred by those who cannot adjust to soft lenses. It is easier to clean hard contacts, but getting used to these low-water lenses is a different matter altogether. Many find RGPs comfortable for daily wear once they adjust to the lenses.

Contact lenses, both soft and hard, are classified by their density and duration of wear. Contacts that you can keep on when you go to sleep are known as extended wear, while others are called daily wear. Advanced lenses that can be worn continuously for a month or more before disposal are now available.

Many contact lenses are also capable of blocking harmful ultraviolet light.