A contact lens is a clear disk that focuses light into a focal point on the retina, the light-sensitive tissue at the back of the eye. It is used to correct many vision problems.

The most common lenses are soft disposable lenses that are replaced every two or four weeks and rigid gas permeable (PMMA) contacts that are worn for 5 to 10 years. All contact lenses are safe to wear when specific handling, care, and replacement procedures are followed.

Soft lenses

Soft lenses are made of plastics that encase water and allow oxygen to pass through the lens to the cornea. They are the most common type of contact lenses and many people find them comfortable, especially if they were previously wearing glasses.

Disposable soft lenses are worn for a day and then discarded, reducing the risk of complications from exposure to contact lens solutions. Two-week and monthly disposables are also available for those who prefer a longer wear schedule.

Daily disposable silicone hydrogel (siho) lenses have a high water content and are thin, which can increase comfort. Novel features like 'flat-pack' lens blister packs and inversion indicators have been developed for handling, but the putative benefits of these innovations have not been confirmed in clinical trials.

Hard lenses

Before the advent of rigid gas permeable (RGP) lenses, the contact lens industry used a variety of materials for hard lenses. These lenses were called “hard” because they did not allow much oxygen to reach your eyes. Today, most hard lenses are made of RGP material and can be more comfortable than their older counterparts.

Whether they are soft or hard, all contact lenses must be carefully cleaned to prevent buildup of protein and lipid debris that can cause eye irritation and other problems. Your optometrist will discuss the best cleaning methods for your needs and lifestyle.

Aside from the initial period of adaptation, hard contact lenses provide clear, crisp vision. They are a great choice for patients with irregular corneal shapes and those who need a higher prescription. However, they do require annual polishing at your eye appointment and daily at-home cleaning. This helps to prevent abrasions on the cornea, which can emphasize blurry vision.

Scleral lenses

Scleral lenses are wider and rigid than corneal contact lenses, and they cover the cornea and sclera (the outer layer of the eye). They are used to treat keratoconus, severe dry eye syndrome, and refractive errors. They provide excellent comfort and vision for many patients.

They can reduce dependency on artificial tears, and they help prevent glare from digital screens. They also have larger optic zones that stay in place all day, minimizing the effects of light reflections such as starbursts and halos around lights.

Since they protect the eye from dust, pollen, smoke, and pet dander, scleral lenses can ease allergy symptoms. They can also be used to treat other ocular surface conditions, including dry eyes. Patients who wear scleral lenses should be taught how to properly insert and remove them, and they should always follow their eye care professional’s specific instructions. This can be challenging for those who have worn regular contact lenses, so the process may take some time and supervised practice to master.

Follow-up appointments

A contact lens follow-up appointment is a chance for the eye care professional to check if the contacts are performing properly. This may include assessing how comfortable the lenses are after wearing them for longer periods of time, or evaluating whether there are any signs of irritated eyes or dry eye syndrome.

The doctor will also take additional measurements and tests to make sure the prescription is correct. Because a contact lens sits directly on the surface of your eye, it’s important that it fits correctly.

Your eye care professional can assess how your eyes respond to the contact lenses by observing the behavior of the tear film and corneal surface. Then, they can adjust the prescription as needed to ensure clear and comfortable vision. They can also teach you proper contact lens care and wear habits, which will help reduce the risk of complications such as eye infections. This is especially important for first-time contact lens wearers.