A contact lens is a lightweight, aesthetic, or therapeutic correction product that is usually positioned directly on the eye’s cornea. For wearers, contact lenses have many advantages, including beauty and practicality.
Compared to eyeglasses, many individuals prefer to wear contact lenses because they have a wider field of vision, they do not steam up, and they are more appropriate for a variety of athletic activities.
Depending on the construction material, wear time, replacement schedule, and style, contact lenses differ from each other. Contact lenses are also referred to as medical devices in the United States, and they require a prescription from a licensed eye care practitioner.
Some lenses are categorized in terms of material, design, and even features. Below are the different types of contact lenses, each with its unique design and function.
Material
It is important to think about the material of the lens when deciding what sort of contacts are best for your everyday use. There are five types of lenses under this category, and the materials they are made from can differ depending on the type of lens.
Rigid Gas Permeable (RGP) contact lenses
Also known as Gas Permeable (GP), the Rigid Gas Permeable (RPG) contact lenses are the first plastic lenses that sat only on the cornea and were developed around 1940. PMMA (polymethyl methacrylate) was used to make this plastic.
Compared to other types of contact lenses, RGP seemed to be more comfortable because the lens was very small. This lens also did not allow oxygen to pass through, and as rigid permeable gas was intended to address this issue in the 1970s. This mirrored a PMMA lens design but was much healthier as it allowed transmission of oxygen and more tear flow.
Permeable contact lenses (RGPs) with rigid gas are more stable and resistant to deposit accumulation and usually offer a clearer, crisper vision. Since they last longer than soft contact lenses, they tend to be less costly over the life of the lens.
They are easier to manage and less prone to tearing. They are not convenient initially as soft contacts, however, and it may take a couple of weeks to get used to wearing RGPs, compared to a few days for soft contacts.
Soft contact lenses
Soft lenses are designed from gel-like, water-containing plastics called hydrogels. Features of these lenses include being lightweight and thin, as well as being form-fitting to the eyeball’s front surface.
In the 1970s, developers experimented with HEMA (hydroxyethyl methacrylate), a soft plastic substance. This substance absorbed water and was so it could overlay over the cornea.
HEMA lenses offered instant comfort because the plastic conformed to the shape of the eye, and it was very comfortable. HEMA also allows oxygen to pass through to the cornea.
These lenses were usually designed for a pair to last for about a year. The contact lens industry has, therefore, pushed forward at a high rate of speed.
Disposable contact lenses
Soft disposable lenses entered the market in the late 1980s and early 1990s, making contact lenses more affordable and comfortable for people to use.
Depending on the type of lens size, these lenses are intended to be worn for up to two weeks, one month, or one quarter of the year. Soon after, they launched daily disposable lenses. For one day only, daily disposable lenses are worn and then thrown away.
Hybrid Contact Lenses
The primary reason for the design of hybrid contact lenses was to combine two different types of contact lenses; the crisp vision consistency of GP contacts with the initial comfort and flexibility of silicone and soft lenses. There is a gas-permeable area in the middle of the lens that is highly rigid.
The edges of soft or silicone lens material surround the circular area. Despite the fact that this lens blends the best qualities of two different styles of contacts, in the United States, there is only a very small number of people wearing these.
This may be true because the lenses are difficult to fit, and when they need to be replaced, the soft and silicone lenses are often the most costly.
Silicone contact lenses
As we all know, hydrogel lenses are actually soft lenses, so with that, we can carefully deduce that the next stage of soft lenses is silicone hydrogel lenses. Throughout the lens, they have more pores, allowing for more oxygen to make its way to the cornea.
The focus in recent years has turned to a silicone-based plastic that allows even more oxygen to flow through the plastic to the cornea. In addition, manufacturers continue to work hard to create a plastic that is more “wettable” and does not dry out after hours of wear.
PMMA
PMMA, which stands for polymethyl methacrylate, is made of a plastic material that is rigid and clear. For a shatterproof glass window substitute, this same material is often used. It is commonly sold under the names of Perspex, Plexiglass, and Lucite trademarks.
While PMMA lenses offer the best quality of vision, they do not allow oxygen between the lens and the cornea, making it hard for the eye to adjust to them. These are now considered old-fashioned, or more generally referred to as rough contacts.
These have been replaced almost entirely by GP lenses and are only prescribed on the fewest occasions.
Design
Depending on the intended use, both types of contact lenses (silicone and standard hydrogel) come in different designs, and they include;
Cosmetic contact lenses
These include your coloured lenses, as well as your costume lenses. Although these may be made to help correct vision difficulties, their primary function is to dress up in costumes or theatrical use.
Multifocal contact lenses
These lenses consist of multiple power zones that either correct farsighted or near vision. This type of lens helps correct Presbyopia and, at times, will also correct astigmatism.
Toric contact lenses
These lenses combine their powers to correct astigmatism, as well as nearsightedness or farsightedness through opposing meridians of the lens.
Spherical contact lenses
These shaped lenses would have the same amount of visual correctness for either nearsightedness or farsightedness in the entire lens.
Additional Features
Some lenses are known to have additional features and functions which help them stand out from the rest.
Myopia Control Contact Lenses
Myopia Control Contact Lenses are known as lenses that are currently in the developmental stage. They are being introduced in young children to inhibit, but ideally completely avoid, the development of nearsightedness.
Coloured Contacts
Coloured lenses are not the usual types of contact lenses. When they are trying to change the natural colour of their skin, people use these. However, you can pick a colour that is totally different from your natural eye colour and give yourself a fresh new look if you want to be more adventurous.
Scleral contact lenses
Scleral lenses are becoming increasingly common. Since today’s production methods are assisted by computer design, it is possible to design scleral lenses so that they are extremely comfortable. Scleral lenses are primarily used by people with substantial quantities of astigmatism, severe dry eyes, and people with degeneration and corneal deformity.
Contact Lenses For Dry Eyes
Chronic dry eyes are a real thing, and specific types of contact lenses (mostly soft contacts) are now being made to help minimize the risks of contact-related dry eyes. These lenses appear to be very permeable to your eye and are pliable.
Prosthetic Contacts
Not all types of contact lenses are specifically made to improve eyesight. Prosthetic lenses have been created to support individuals who may have sustained an eye injury or disfigured their eyes in some way. These lenses are custom-made to fit the other eye of the individual to make it look the same.
Special Effects
Usually, special-effect lenses are used in stage performances or when people dress up in costumes. The aim is to make your eye’s form appear unnatural and not human. A vampire or a cat-eye lens will be typical examples.
UV-Inhibiting Contacts
Currently, there are some soft lenses developed to help prevent cataracts and other long-term damage from the eyes that can cause UVA rays. As contacts only cover a small portion of the eyeball, it is always a good idea to wear protective eyewear over your eyes when out in the heat.
Bifocal Lenses
Bifocal contact lenses are advanced soft contact lens that can fix these abnormalities, such as stigmatism or Presbyopia. If you have astigmatism, you can also stay bifocal and glasses-free until after age 40 using these lenses.
Custom Contacts
You might consider ordering custom lenses if you have tried all the contact options open to you but still have not found the right pair. They will need to measure and scan the shape of each individual eyeball to meet your vision needs in order to get custom lenses made.
