Types of Contact Lenses

Every day, millions of people wear contact lenses to help them see clearly. There have been numerous advancements in both lens materials and designs, allowing most individuals to wear contact lenses successfully. As a result, there are more contact lens choices available than in the past. If you have worn contact lenses in the past but discontinued use due to discomfort or unacceptable visual results, it may be time to revisit your options. At Northern Waters Ophthalmology, we will help you select the best option for you based on the health and shape of your eyes, the type of correction you require, your previous contact lens experience, your tear production and your lifestyle.

Soft Contact Lenses

Soft contact lenses are the most common type and account for over 85% of contact lenses dispensed. Traditional soft contact lenses are made of soft plastic polymers and water. They allow oxygen to permeate through the lens material to the cornea and are generally quite comfortable. Advantages of soft contacts include comfort as well as the availability of many different prescriptions and designs. A potential disadvantage is that for some prescription strengths, the visual acuity may not be quite as crisp compared to that achieved by gas permeable lenses. Your eye care professional can help you determine which design will be best for your prescription.

Disposable Contact Lenses

Disposable contact lenses are soft lenses designed to be discarded on a daily, weekly, bi-weekly, or monthly basis. By replacing lenses on a regular basis, long-term protein deposits (which can affect vision, comfort, and the health of the eyes) do not build up. Disposable lenses are convenient and require less maintenance than traditional soft lenses. It is important that disposable contacts be replaced at their designated time to reduce the risk of eye infection. Disposable lenses are available in most prescriptions.

Extended Wear Contact Lenses

Extended wear contact lenses are gas permeable or soft lenses, which are sometimes worn continuously for up to 30 days. While extended wear lenses offer the convenience of not having to remove them at night, sleeping in contact lenses results in a higher risk of developing infections, sight-threatening corneal ulcers and abnormal blood vessel growth in the cornea. Therefore, some doctors will not recommend that extended wear lenses be worn in this manner.

Tinted or Cosmetic Contact Lenses

Tinted contact lenses are soft lenses that enable the color of the iris to appear to be a different shade. These lenses are available in many exciting colors and can provide a subtle or dramatic change in the appearance of the eyes. They are not, however, available for all prescriptions.

Hard Contact Lenses

Before soft contact lenses were introduced, hard contact lenses made of PMMA (polymethyl methacrylate) were used. These lenses did not allow for oxygen transfer to the cornea and often caused the cornea to swell. For this reason, hard contact lenses are considered obsolete and are rarely used.

Rigid Gas Permeable Lenses

Rigid Gas Permeable (RGP) or Gas Permeable (GP) lenses are sometimes mistaken for the old-fashioned hard contact lenses but are more pliable, more comfortable and most importantly, allow oxygen to access the cornea. In fact, gas permeable lenses transmit more oxygen to the cornea than do traditional soft contact lenses. Because gas permeable lenses are rigid, they do not change their shape with a blink and can offer sharper vision than soft contacts do. They are much more durable than soft lenses and because they do not contain water, proteins and lipids do not adhere to them as easily as with soft lenses. GP lenses also come in numerous bi-focal and multi-focal designs.

The biggest disadvantage to GP lenses is that they are not always immediately comfortable compared to soft lenses. In general, it may take a few days for the eyes to adapt to them and they need to be worn fairly regularly to achieve maximum comfort. Also, because these lenses are smaller in size, they can dislodge from the eye more easily than soft lenses.

Toric Contact Lenses

Toric contact lenses are designed to correct astigmatism. They are available in both soft and gas permeable designs. These lenses have one power vertically and another power horizontally and are weighted at the bottom, allowing the lenses to center correctly on the eye. Toric lenses are more difficult to fit and generally require more time from the patient and doctor for fitting and adaptation.

Bifocal Contact Lenses

Bifocal contact lenses, similar to bifocal glasses, have more than one power to allow an individual to have clear vision both near and far. They are available in both soft and gas permeable lens designs. Another alternative to bifocal contacts is monovision correction. With monovision, one eye is used for distance vision and the other eye is used for near. Both of these lens types require more time to fit, and more time and patience from the patient for adaptation.