All of the Types of Contact Lenses Explained By WebEyeCare
Mar 10th 2023
Contact lenses are vision correction alternatives to glasses. They come in various materials, forms, colors, and wearing schedules. Millions of people wear contact lenses for vision correction or aesthetic reasons.
This article examines the types of contact lenses available and their meaning for your vision.
What Are Contact Lenses?
Contact lenses are thin curved lenses placed on the eyes to remedy a vision problem, protect an injured eye or for cosmetic purposes. Contact lenses have been around for decades, though they have recently become popular.
Contact lenses are medical devices, and the Food and Drug Administration (FDA) regulates their sale and use, including cosmetic contacts. Improper use of contact lenses can cause eye health complications and vision loss.
What Kind of Contacts Should I Get?
The kind of contact lens you should get depends on your specific needs and lifestyle. For example, if you have astigmatism, you will be best served by using toric contact lenses.
If you have a busy schedule and do not want the hassle of cleaning your contacts lenses every day, then daily disposables will be suitable for you.
People who desire comfort above all else will probably benefit more from using conventional soft contacts lenses. The best way to determine what kind of contacts you should get is by speaking with your eye doctor.
Contact Lens Material: What Are They Made Of?
The first contact lenses were made from hard glass materials. Today, contact lenses are made from soft plastic polymers.
Soft contacts are made from hydrogel and silicone hydrogel polymers, while hard contacts are made from polymethyl methacrylate (PMMA) or Plexiglas.
Hydrogel is one of the most common contact lens materials, and it is used in the manufacturing of a soft contact lens. It is a thin gel-like water-containing polymer.
Hydrogel is easy to use and rests on the eye comfortably. It is the perfect contact lens for dry and sensitive eyes due to its biocompatibility.
Silicone hydrogel combines hydrogel with silicone to let more oxygen enter the cornea, making them suited to long-term use. However, these materials tend to accumulate proteins and debris from tears.
Polymethyl Methacrylate (PMMA)
PMMA or Plexiglas is a stiff plastic used to manufacture a hard contact lens. It is biocompatible, provides clear vision and can be molded to fit the eye.
However, PMMA does not allow much oxygen to get into the eye, putting users at risk of “overwearing syndrome.” Thus, manufacturers are designing rigid gas permeable lenses to allow for breathability.
Soft Contact Lenses
Traditional soft contact lenses are made from soft plastics like hydrogel and silicone, which allows the eyes to receive more oxygen.
They are comfortable, easy to use, and correct several vision disorders, including myopia, hyperopia, astigmatism, blurred vision, and presbyopia. Some soft contacts come as daily disposables, while others can be worn for several days before disposal.
Silicone Hydrogel Contact Lenses
Silicone hydrogel contact lenses combine hydrogel and silicone to provide oxygen permeability up to five times that of standard hydrogel lenses, making them ideal for people with stronger prescriptions or those who suffer from dry eyes.
They are also easier to handle and can be worn for long periods, though they carry a higher risk of collecting protein deposits.
Gas Permeable Contact Lenses
Gas-Permeable (GP) or Rigid Gas Permeable (RGP) contact lenses are made from durable materials that allow oxygen to enter the eyes.
They are crafted using silicone-containing materials and are smaller in diameter than soft contact lenses, covering less of the cornea. RGP lenses are rigid, so there is little risk of tearing or ripping. They are easy to maintain and do not require frequent replacement.
Gas permeable contact lenses maintain their shape on the eye and provide sharper vision. However, they take time for the corneas to adapt to them and have a higher possibility of dislodging during physical activity due to their small size.
Hybrid Contact Lenses
Hybrid contacts lenses attempt to provide the comfort of soft contacts and sharp vision of GP lenses. They consist of a rigid gas permeable center and a skirt made from soft lens material. Hybrid lenses are ideal for individuals with strong astigmatism and those who use soft lenses but want clearer vision.
Learning to insert, remove, and care for hybrid lenses takes some education and may not be ideal for everyone. Fitting hybrid lenses often takes more time than other lenses and is usually costlier.
PMMA lenses are made from polymethyl acrylate (Plexiglas), a lightweight, shatter-proof glass alternative.
PMMA is transparent, inert, and biocompatible with the eye. It is malleable, allowing it to be shaped to correct refractive errors. However, PPMA is not widely used for contact lens manufacturing because users find it difficult to adjust to its rigidity.
It is also not gas permeable, which can obstruct oxygen flow into the eye—manufacturers design PPMA contacts to be as small as possible to reduce the surface they cover.
They also shape PPMA lenses in a way that creates a space between the lens and cornea surface, making it easy for tears to get under the lens and supply the eyes with oxygen. However, this space also makes it easy for lenses to fall out.
Conventional Vs. Disposable Contacts
If you are new to wearing contacts, you may be wondering whether to choose regular or disposable contacts. Where you stay on the conventional vs. disposable contacts divide generally depends on your lifestyle and what you want from your contacts.
Traditional contact lenses have been around for a while and are popular among wearers. They require proper cleaning and handling. On the other hand, disposable contacts are designed to be worn and replaced with a fresh pair daily.
Disposable Contact Lenses
Disposable contact lenses are popular for their ease of use. Wearers use and replace these contacts with a fresh pair either each day, each week or two, or once a month. Disposable contacts may result in more waste generation from their frequent replacement than conventional lenses and may be more expensive in the long term.
Weekly, Biweekly, and Monthly Contact Lenses
Weekly contact lenses are to be used and thrown away after one week. They are more durable than daily disposable contacts, and some are approved for overnight wear. Weekly contact lenses are ideal for people who want convenience but do not like the idea of replacing their lens daily.
Biweekly contacts are designed for continuous use for up to two weeks. Weekly and biweekly contact lenses must be cleaned and stored at the end of each day.
Monthly contact lenses can be used for up to 30 days before being replaced with a new pair. You must clean and store them each day to prevent the buildup of eye deposits. Additionally, they are eco-friendlier than other types of lenses and usually more affordable.
Daily Contact Lenses
Daily contact lenses are contacts that must be removed each night before sleeping. Since there is no need to clean or store them, wearers use and replace these contacts with a fresh pair each day. as they are not approved for extended use. These lenses are great for people who do not want to bother about lens cleaning and storage.
Extended Wear Disposable Contacts
Extended wear disposable contacts are designed to be worn continuously for seven days and six nights. Nonetheless, newer silicone hydrogel contacts can be worn for up to 30 days straight.
Extended wear contact lenses are ideal for people with active or unpredictable schedules and those with severe refractive errors which need to see clearly at all times, including sleeping with contacts in so they can see when they wake up.
Extended wear contacts are made with gas permeable materials permitting oxygen flow into the eyes. This make-up makes them suitable for more prolonged use. However, they carry a higher risk of infection and can cause eye irritation or inflammation.
Conventional Contact Lenses
Conventional contact lenses are worn for several months up to a year. They require regular cleaning, disinfection, proper handling and are available as daily wear or extended use contacts.
Nevertheless, advances in disposable lens technology have seen a steady decline in their demand. On the flip side, they carry a high risk of infection due to deposit and protein formation resulting from extended use.
Types of Contacts Based on Condition
Some contact lenses are designed to correct specific vision problems. Here, we explore the types of contacts based on the eye conditions they correct.
Toric contact lenses are designed to correct astigmatism, a refractive error resulting from an irregular curvature of the cornea or lens.
The shape of the cornea in people with astigmatism means that the eyes refract light unevenly, leading to blurred, hazy vision and an inability to see fine details. Among other types of contact lenses for astigmatism, toric contact lenses provide refractive powers on the horizontal and vertical orientations to specifically correct astigmatism.
Toric lenses are designed with thin-thick zones, lens truncation, and ballasting to help them stay on the eyes. Every eye with astigmatism is unique, so a doctor must fit toric contacts due to their specific orientation.
Wrongly fitted toric lenses can affect visual acuity. Toric lenses come as daily contacts, extended wear and can also come as colored contacts.
Multifocal and Bifocal Contacts
Multifocal contacts have multiple prescriptions on a single lens. Bifocal contacts have two prescriptions, while the term “multifocal” describes any contact lens with more than two lens powers on one lens. Multifocal and bifocal lenses are prescribed to correct presbyopia, an age-related inability to focus on close objects. People with presbyopia struggle to read up close and may experience blurred vision.
Multifocal contacts have varying powers on a single lens that allow transition between the prescriptions for reading, distance, and intermediate correction, saving the wearer the need to alternate between reading glasses or single prescription contacts. Multifocal and bifocal contacts provide sharp, natural vision and have an easy adaptation period. Some may also be used to correct myopia, hyperopia, and astigmatism.
Spherical Contact Lenses
Contact lenses are shaped differently to address specific vision errors. Spherical contact lenses are designed to replicate the shape of the eye.
They possess the same optical power throughout the lens and are used to correct myopia, hyperopia, and presbyopia. Due to their even shape, spherical contacts cannot correct astigmatism or vision errors that arise from the eye’s curvature.
Custom Contact Lenses
Some people find that no contact lens can meet their vision needs due to an irregularly-shaped cornea, strong astigmatism, or general discomfort from wearing regular contacts.
Custom contact lenses are tailor-made to meet specific individual needs of clearer vision and comfort.
Scleral lenses are specialized lenses made from gas-permeable materials and designed to treat eye-related conditions like keratoconus, dry eye, post-surgical complications and help people who have trouble using contact lenses due to an altered cornea. Since they do not touch the eye, scleral lenses rest on the sclera (the white part of the eye) and are technically not contact lenses.
The space between the back of the scleral lens and the corneal surface contains sterile saline fluid that hydrates the eye, fills in corneal irregularities, and provides a perfectly rounded eye surface leading to clear vision.
Myopia Control Contact Lenses
Myopia control contact lenses are a new type of single-use contact lenses that slow the progression of myopia (shortsightedness) in children. Some children develop myopia and see it progress as they grow older.
Myopia is the most frequent cause of corrective visual impairment worldwide, and these specialized contact lenses correct and slow down the progression of near-sightedness in children.
Monovision Contact Lenses
Monovision contact lenses are worn on one eye to correct for near vision and on the other to correct for far vision. These lenses address the difficulty in changing focus between far and close objects in patients with presbyopia.
Monovision lenses work by tricking the brain into thinking that the lens is part of the eye. Monovision contact lenses have an adjustment period, as the brain needs time to get used to the new lenses. The lens for far vision is typically placed on the dominant eye.
Other Contact Lens Options
Contacts for Dry Eyes
Having dry eyes can make using contact lenses a bit inconvenient. Dry eyes cause pain, burning, or a gritty sensation like an object in your eyes. However, there are several contact lens options for people with dry eyes.
Colored lenses allow wearers to change their eye color for cosmetic purposes or for vision correction. All contact lenses are medical devices, and you still need a prescription for colored contact lenses.
Special effect lenses are soft opaque contacts lenses used for costume and novelty uses. They cover the eye color, and their center lies over the pupil to allow you to see clearly.
Like other contact lenses, special effects lenses are medical devices and require a prescription.
Prosthetic lenses mask flaws and improve the appearance of an eye or cornea damaged or disfigured by congenital abnormalities, disease, or traumatic injury.
They provide wearers with therapeutic, psychological, and cosmetic benefits.
UV-inhibiting lenses shield the eyes from harmful ultraviolet rays from the sun. They are coated with a transparent, photochromic chemical that reflects UV light away from the eyes.
The Importance of Contact Lens Care
Contact lenses are medical devices that require proper care and maintenance. Daily disposable contacts are generally the safest contacts and require minimal care. However, if you use conventional contacts, you must adopt strict contact lens care practices.
Caring for your contacts extends its lifespan and protects your eyes from harmful infections. Ensure you follow the manufacturer’s guidelines on cleaning, wearing, removing, handling, and storing contact lenses.
Understanding Your Contact Prescription
Your contact lens prescription holds specific information regarding the type and use of contacts you need. A contact prescription contains numbers and abbreviations that look foreign to a new user.
However, it is quite helpful to learn how to read your contact lens prescription before shopping for contacts, especially if you are buying online. The details of your prescription ensure that you get contacts that are comfortable, safe, and provide the sharpest vision.
Are Contacts Better Than Glasses?
There is no right or wrong answer to the “are contact better than glasses” question.
Whether you opt for contacts or glasses is a matter of needs, preference, and lifestyle. You do not even have to choose between the two; some people alternate between using contacts and glasses depending on their current situation.
Contact lenses conform to the eyes and provide a more natural feel than glasses for most people. They do not significantly alter your look and can be used for sports and other physical activities. However, they require special handling and maintenance, which can be tedious for many people, and generally speaking contacts cost more.
Glasses are easy to use, come in different styles, and offer some form of protective eyewear against debris, wind, and dust. However, glasses can distort vision, especially for people with strong prescriptions, they fog up in cold weather, and some do not like the feel on their face. Ultimately, the contacts vs. glasses decision comes down to the individual and what is best for them.