A Contact Lens Primer, Part I – Soft Contact Lenses
Contact lenses have become an immensely popular method of correcting vision over the last few decades, especially in Western Civilization. Contact lenses are small, medical devices that are placed directly on the front of the eye (the cornea, and sometimes the sclera as well). In many cases, they act as a substitute for glasses. Due to their relatively low profile, contact lenses present many advantages over traditional glasses. They are useful for active lifestyles, playing sports, and any other activity that would be performed better without the hindrance of glasses.
Contact lenses come in many shapes and sizes. Ultimately, your eye doctor will decide which contact lens is right for you. Many factors come into play when I decide what contact lens to fit on a patient: prescription, corneal curvature, propensity for dry eyes, lifestyle, and eye anatomy are just a few of these factors.
Currently, there are two major types of contact lenses available on the market: soft contact lenses and rigid gas permeable lenses. Additionally, many variants of specialty contact lenses exist. Today, we will talk about soft contact lenses.
In recent years, soft contact lenses have become the most popular contact lens in use. A combination of flexible plastic polymers and water make up the composition of a contact lens, however the exact material differs per each contact lens brand. Soft contact lenses come in a variety of modalities:
- Daily Wear – lenses are worn throughout the day and either thrown away or cleaned/placed in a storage container overnight
- Extended Wear – lenses are worn throughout the day and night (continuously) for a set period of time
Daily wear lenses have advantages in that the adaptation period to the lens is very short. These lenses tend to be more comfortable and more difficult to dislodge than RGP lenses
They are available in tints and multifocal varieties as well. Some disadvantages of daily wear lenses include vision not being as sharp as rigid gas permeable lenses and that lenses wear out and must be replaced in a timely fashion.
Extended wear lenses hold advantages in the amount of time they can be kept in the eye – which normally ranges from a week to a whole month. However, wearing a contact lens continuously has some significant disadvantages. The lenses tend to become less comfortable through their cycles due to depositing and wear. Also, extended wear contact lenses put the user at a higher risk for complications such as eye infections.
Soft contact lenses also have different life cycles:
- Daily Disposable
Daily disposable contact lenses have gained quite a bit of popularity in recent years, and with good reason. Having a fresh pair of contact lenses everyday allows an individual to have more comfort and be less prone to a contact lens related eye infection. They also provide an advantage when performing outdoor activities, sports, or in a dirty/dusty environments; since a fresh lens is used everyday.
In terms of types of vision correction available in soft contact lenses, three major types of contact lenses exist:
- Toric (Astigmatic)
This combination of soft lenses allows us to correct a large majority of refractive errors. Many innovative modalities are employed in correcting astigmatism and presbyopia with toric and multifocal lenses respectively.
If you are interested in being fit with soft contact lenses or have questions about contact lens candidacy, please do not hesitate to contact us.
Next week we will discuss rigid gas permeable lenses, stay tuned!
-Dr. Aaron Neufeld
Dr. Aaron Neufeld is the Chief Optometrist at Los Altos Optometric Group and primary author and editor of The EYE Digest.
Contact him with questions or ideas for future articles at (650) 948-3700 or firstname.lastname@example.org