Contact Lenses: Types of Contacts
Advances in contact lens technologies have created many options. Today, contact lenses are likely to be described in one or several of the
By their prescribed wearing period: The time that the lenses are left in the eyes.
Daily Wear: Lenses prescribed for daily wear are to be worn only during waking hours, usually up to a maximum of 18 hours. Daily wear lenses
are removed at night and cleaned and disinfected after each removal.
Extended Wear: Extended wear lenses may be worn on an overnight basis for up to seven
consecutive days (six nights). You should wear your lenses on an extended wear basis only on the
advice of your optometrist.
Extended wear lenses generally have a higher water content or thinner center thickness than other
lenses and permit more oxygen to reach the eye. However, their use has been linked to a higher
incidence of eye problems, including serious corneal ulcers that can result in vision loss. Extended
wear lenses need to be cleaned and disinfected at recommended intervals or discarded after use.
By their replacement schedule: The time interval for replacing lenses.
Contact lens are often prescribed with a specific replacement schedule suitable to your specific needs. Planned (or Frequent) Replacement
contacts are disposed of and replaced with a new pair according to a planned schedule. Unplanned replacement lenses (often called conventional
lenses) are not replaced according to a pre-determined schedule. They are typically used for as long as they remain undamaged, usually around
12 months for soft lenses. This type of lens is outdated and reserved for very high prescriptions or unusual circumstances where a frequent
replacement lens is not available.
Why replace lenses frequently?
Almost immediately after they are inserted, contact lenses begin attracting deposits of proteins and
lipids. Accumulated deposits, even with routine lens care, begin to erode the performance of your
contacts and create a situation that presents a greater risk to your eye health.
A specific replacement schedule helps to prevent problems before they might occur. Contact lens
wearers, in turn, enjoy the added comfort, convenience and health benefits of a planned
replacement program. Planned replacement lenses are generally a thinner design or are made of
different, more fragile materials with a higher water content than unplanned replacement or
conventional contact lenses.
Based on a complete assessment of your needs, a prescription for planned replacement lenses
may call for replacement:
- Every 1-2 weeks
Except for daily disposables, planned replacement lenses require cleaning and disinfection after each period of wear unless they are discarded
immediately upon removal. Planned replacement lenses can be worn as daily wear -- removed before sleep -- or as extended wear, if recommended by your doctor.
By the type of vision correction for which they are designed:
- Spherical (For near- or farsightedness -- myopia or hyperopia)
- Toric (For astigmatism)
- Multifocals (For presbyopia - the loss of ability to focus on reading or close-up activities
As an alternative to special multifocal contact lenses, many doctors use a system called monovision where one eye is fitted with a distance lens
and the other with a reading lens. Approximately two-thirds of patients adapt to this type of contact lens wear.
By the type of tint they have:
Contact lenses may be described as clear or tinted. Tints are used to make lenses more visible
during handling, or for therapeutic or cosmetic reasons. Tints can enhance eye color, or change it
Three categories of tinted contact lenses are available.
- Cosmetic enhancement tints are translucent and are designed to enhance your natural eye color. They are best for light-colored eyes (blues, greens, light hazel or grays). When wearing these tints, the color of your eye is a blend of the lens tint and your natural eye color and iris pattern.
- Opaque or "cosmetic" tints change the color of your eyes whether they are dark or light. The pattern on the lens, which is colored, overlies the colored part of your eye, resulting in a color with a natural look.
- Visibility tints are very pale, colored just enough to make the contact lens visible while you are handling it. They usually have no effect on eye color.
By the basic type of material of which they are made:
- Soft (hydrophilic)
- Rigid Gas Permeable
Below is a brief comparison of Soft and Rigid Gas Permeable (RGP) contact lenses. A thorough eye examination and a better
understanding of your specific vision requirements will help determine the best options for you.
Soft Contact Lenses
- Greater initial comfort than hard or rigid gas permeable (RGP) lenses.
- Shorter adaptation period for new wearers.
- Ideal for intermittent wear.
- Less susceptible to the intrusion of foreign objects under the lens, such as dust.
- Less sensitivity to light than with hard or RGP lenses.
- Rarely fall out of the eye, making them ideal for sports, particularly contact sports such as football or basketball.
- Available in tinted versions.
- Less durable than hard or RGP lenses.
- May dry out, causing discomfort for some, especially under a hair dryer, in hot rooms, or in windy, dry weather.
- More involved lens care, especially for conventional soft lenses.
- May absorb chemicals from the environment, which can cause irritation.
Rigid Gas Permeable (RGP) Lenses
RGP lenses are, as the name implies, rigid, but the plastics of which they are made are somewhat more flexible than hard lenses. RGP lenses
offer the advantage of allowing more oxygen to pass through to the eye. Sometimes they are referred to as "Oxygen Permeable Lenses". They are
available in daily wear and extended wear options.
RGP lenses have the following advantages and disadvantages:
- Good vision.
- Correct most corneal astigmatism.
- Good durability.
- Good handling characteristics.
- Less initial comfort than soft lenses.
- Longer adaptation period required than soft lenses.
- More easily dislodged.
- Can scratch and break.
- Intermittent wear less feasible
- More susceptible to the intrusion of foreign objects under the lens, such as dust.
You only get one pair of eyes. Let us help you care for them. Call anytime with your questions or concerns.