Contact lenses are available in a variety of forms to meet different purposes. It’s important to use contact lens according to the directions provided by your eye care professional. Contact lenses must be worn safely and responsibly, or serious eye injury may occur.

In your prescription, you will see a power/sphere number followed by a plus or minus sign and a base curve and cylinder (CYL). These numbers convey the shape of the lens needed to correct your refractive error.

Lenses are used to correct vision

A contact lens is a thin disc of plastic or glass that sits directly on the eye to correct vision. It is shaped to fit the curve of the cornea. Different lenses are used to correct different vision problems, like nearsightedness, farsightedness and astigmatism. They are also available in many different strengths or diopters, as indicated by a prescription from an eye care provider.

Soft contacts are the most popular type of lens. They can be worn for extended periods of time and are more comfortable than hard contacts. However, they are more likely to absorb particles, chemicals and bacteria than rigid or gas-permeable lenses. This can cause corneal hypoxia, which if not corrected, can permanently decrease vision.

Rigid gas permeable (RGP) contact lenses are stiffer than soft lenses, but they hold their shape well and let oxygen pass through to the cornea. They are often used to treat astigmatism and other corneal irregularities. Rigid contacts are also less prone to collecting irritating deposits than soft lenses, but they can take longer to get used to and may be more uncomfortable at first.

They are made of plastic

Many people are familiar with contact lenses, which sit comfortably on the surface of your eye to correct your vision. They can be worn for a few hours at a time or longer, depending on the type of lens and your doctor’s recommendations. They are also available in a variety of colors to enhance your natural look or even change it completely, for example, from brown to blue. There are even special-effect lenses that allow you to look like a cat, vampire, or other alter-ego.

Early contact lenses were affixed with wax or made of thick blown glass, which was very uncomfortable and required weeks to adjust to. Later, polymers were developed that allowed oxygen to pass through the cornea and conjunctiva. These are now known as rigid gas permeable (RGP) lenses.

Today, most contact lenses are made from hydrogel plastics that incorporate water into their design for added hydration. These materials are also very soft and comfortable. In addition, they don’t have the protein-binding properties of previous generations of hard lenses.

They are made of metal

Contact lenses are used for many reasons, including cosmetic and therapeutic. They are made from a variety of materials and are available in different shapes and colors. Contact lens wearers must follow the prescribed wear schedule for optimal eye health and safety. Some of these schedules may include daily disposables, biweekly, or monthly replacement.

When handling contacts, it is important to use clean hands. Touching the lenses with dirty hands can transfer lint, dirt, and other debris to the lens. In addition, using towels or tissues can transfer lipids from the skin to the lens surface, which can lead to irritation.

Research has also shown that small physical pollutants, such as fungi spores and plant pollen, adhere to contact lens surfaces in high concentrations. Multipurpose solutions and rubbing with fingers do not significantly remove these contaminants. However, a new cleaning technique uses a soft and porous polymer to physically peel these pollutants from the lens surface.

They are made of glass

A contact lens is a thin disc of glass or plastic that sits directly on the eye to correct vision. It can be either soft or hard, and is shaped to conform to the cornea. It can also be used for cosmetic purposes. Many contacts require a prescription and must be ordered from an ophthalmologist, optometrist or licensed optician.

Rigid gas permeable (RGP) contact lenses are made of a more durable material than soft lenses. They are less prone to deposit build-up and typically provide clearer, crisper vision. However, they may take weeks to become comfortable, compared to several days for soft lenses.

Soft contact lenses are made from a special type of plastic mixed with water, which allows oxygen to pass through the lens to the cornea. They are more comfortable and have less risk of infection than PMMA lenses, which were popular before the introduction of hydrogels in the early 1970s. They can be worn daily or extended wear and must be removed, cleaned, and stored on a schedule prescribed by the eye doctor.