Many people enjoy wearing contact lenses for cosmetic reasons, including changing eye color (plano lenses) or to increase the luster of natural eyes. These types of contacts require a prescription and need to be properly fitted by an eye care professional.

In the 1970s, gas-permeable rigid plastic materials were developed that allowed oxygen to pass through to the cornea. These new contact lenses are called Rigid Gas Permeable or RGP lenses.

Cornea

The cornea is the clear outer layer of the eye that refracts light and transmits information to the retina, which converts light into nerve impulses, giving you vision.

Contact lenses are small medical devices that sit on the cornea to correct refractive errors and maintain ocular health. They are made of plastic mixed with water that lets oxygen pass through to the cornea and the eye.

Older types of hard contact lenses (polymethyl methacrylate or PMMA) rest on the cornea and restrict passage of oxygen, causing many adverse clinical events. More comfortable, oxygen-permeable rigid lenses were introduced in the 1970s.

The most common problem associated with contact lens wear is irritation of the cornea, called keratitis. If not treated promptly, keratitis can lead to more serious problems such as corneal ulcers.

Lenses

Many people wear contact lenses for optical, therapeutic, preventive, operative and cosmetic reasons. Almost 90% of lens wearers agree that contact lenses have improved their quality of life.

Most contact lenses are soft and made of a material called polymethyl methacrylate (PMMA). Rigid gas permeable contact lenses or GPs are sturdier than soft contacts and offer clearer vision, especially for astigmatism. They also are more resistant to deposit build-up.

Soft lenses are categorized by their replacement schedule, with daily disposables worn throughout the day and then discarded before going to sleep; extended-wear lenses that may be worn while sleeping; and frequent replacement (biweekly or monthly) lenses. The shape of the lens is also important, with toric and bifocal contacts available to correct astigmatism and nearsightedness/farsightedness.

Insertion

The insertion of a contact lens may seem difficult at first but with practice you will find it easier and safer. It is important to always insert your contacts correctly as this will help ensure your eyes remain healthy and clear.

Before handling your lenses make sure your hands are clean. Wash them using an antibacterial soap and then dry them thoroughly with a lint-free towel or cloth.

Keeping your eyes open is essential as blinking can cause your eyelids to close, preventing you from placing the contact correctly on your cornea. It is also helpful to lubricate your eyes by adding rewetting drops.

Finally, double-check the contact lens is inserted correctly – it should form a ‘bowl’ shape on your cornea. If it doesn’t, it is inside out and will need to be removed and re-inserted.

Removal

Before trying to remove a lens, wash your hands thoroughly with soap and water. Then wipe them dry with a clean towel (ideally, one that has been washed and wrung out several times to prevent the spread of bacteria).

If you have trouble removing a hard contact lens, try lubricating it with rewetting drops, multipurpose solution, or sterile saline. Then try sliding the lens down onto your cornea and pinching it out with the thumb and index finger of your dominant hand.

Some people remove a rigid lens by stretching the eyelids and blinking, which breaks the capillary action that adheres the contact to the cornea. This can be painful and is not recommended for everyone. It also may scratch the cornea and cause visual impairment.

Cleaning

To keep contact lenses clean and healthy, they must be cleaned regularly with a contact lens solution. This removes debris and helps to prevent eye infections.

First, wash your hands well with an antibacterial soap and a clean, lint-free towel. This is important, as dirt and oil from your fingers can transfer to the lens or storage case.

Next, pour multipurpose contact lens cleaning solution over your lens. Rub each lens for about 20 seconds (the exact amount of time varies by solution). Then, rinse your lenses and your case as directed on the label.

Hydrogen peroxide-based contact lens solutions are preservative-free and disinfect the lens quickly. However, they must be neutralized with saline to make sure the solution is no longer hydrogen peroxide and will not irritate the eye.