Contact lenses are a great alternative or complement to glasses for those who require corrective eyewear. They come in a variety of forms, made of different materials, and designed for different patterns of wear. Our specialists can help choose the best type for your eyes, furnish you with the correct prescription, and provide expert instruction for proper care and use of your contacts. Read below to learn more about the types of available contact lenses now!
Gas Permeable Contacts:
Gas permeable contact lenses, commonly referred to as RGP or GP lenses, are more rigid contacts made to incorporate silicone that allows them to be more flexible and for oxygen to pass through the lens and to the eye. Although soft contact lenses are more popular, gas permeable contacts offer an array of advantages.
While there are many advantages to wearing gas permeable lenses, there are some disadvantages you may want to consider before deciding which lenses are right for you.
Multifocal and Bifocal Contact Lenses:
Bifocal contact lenses have two powers, one for seeing clearly far and for you seeing clearly close. Multifocal is a more general term for lenses with more than one power. They are designed to aid vision at all distances for individuals who have presbyopia. They are available in both soft and rigid lenses. There are two types of multifocal contact lenses, simultaneous vision lenses and alternating vision lenses.
Simultaneous vision lenses are the most popular type of multifocal contact lenses, and are typically soft lenses. With these lenses, there are certain regions for far, near, and intermediate power. After adjusting, your eyes will learn the power you need and ignore the other lens powers depending on what you are looking at. There are two different designs offered for simultaneous vision lenses. Those being the aspheric design which is multiple viewing powers blended across the surface of the lens with a distance or near power in the center, and the concentric ring design which are bifocal lenses with distance or near power in the center and alternating rings of power around it.
Alternating vision lenses are gas permeable lenses and are designed like bifocal glasses. The bottom part of the lens is for near power while the top has distance power. They move more freely on the eye, and are held in place by how they interact with your eyelids. When looking straight ahead, the lenses will position so you look through the distance part of the lens. When you look down for reading, writing, and the like, your eyelid will hold the lens in place allowing you to look through the near part of the lens. Bifocal contact lenses function very similarly.
Monofocal lenses are also an option. With single vision contact lenses, you will wear a contact for distance vision in one eye and a contact for near vision in the other. These take longer to adjust to, but some find these a better option for their presbyopia.
Contact Lens Material:
Contact lenses are made out of a variety of materials:
Soft lenses are made out of water-containing plastic that covers the entire cornea and makes them easy to adapt to. The most common contact worn today are special soft lenses called silicone hydrogel lenses that allow more oxygen to the eye than traditional soft lenses.
Gas permeable lenses are smaller lenses that are rigid and made of water-less silicone containing compounds that allows more oxygen to reach the eye. They are harder to adapt to than soft lenses, but provide sharper vision.
Hybrid lenses have a GP zone that is surrounded by soft lens material. These allow for the sharper vision of the GP lens but the comfort of soft lenses.
Hard lenses are similar to GP lenses, but are made of plastic that is not permeable to oxygen. They are rarely used today, as most individuals prefer GP lenses.
Contact Lens Wearing Time
There are two types of contacts depending on the recommended wearing time. Daily wear contacts are removed nightly, while evening wear contacts can be worn overnight. Certain brands of extended wear contacts can be worn for 30 consecutive nights, making them commonly referred to as continuous wear contacts.
Contacts should be replaced frequently to prevent build up and contamination that can lead to eye infections.
Soft lenses have several different replacement options:
Daily disposable contacts should be discarded after a single day of wear.
Disposable contacts that are used for daily wear should be discarded after two weeks, and disposable contacts that are for overnight wear should be discarded after one week.
Continuous wear contacts that are for 30 day wear should be discarded monthly.
Planned replacement contacts should be discarded at intervals of one to three months.
Gas permeable lenses are more resistant to contamination and buildup and do not need to be discarded as often as soft lenses. They typically last a year or longer before needing replacement.
Contact Lens Design
There are several types of contact lens designs used to correct various vision problems:
Spherical contact lenses are the most common design. Spherical soft lenses correct farsightedness and nearsightedness. Spherical GP lenses can correct astigmatism, farsightedness, and nearsightedness.
Toric contact lenses, both soft and GP, correct astigmatism.
Bifocal and multifocal contact lenses, both soft and GP, contain different zones for far and near vision to correct presbyopia
Orthokeratology are specialty GP contact lenses that are designed to reshape the cornea during sleep while temporarily correcting myopia and other refractive errors for clear vision without glasses or contacts during the day.
Custom GP contact lenses are also available for individuals with certain conditions, such as dry eye, that make wearing conventional contact lenses difficult.
There are also a variety of other contact lens features including colored lenses, special-effect lenses, and prosthetic lenses. Our doctors will discuss which contact lenses are right for you.
Call today to schedule an appointment with one of our optical staff members!